FILE COPY
United States Environmental
Protection Agency
Association of Metropolitan
Water Agencies
Final Report for
Disinfection By-Products in
United States Drinking Waters
Volume 2 - Appendices
November 1989
JIM James M. Montgomery
Consulting Engineers, Inc.
Metropolitan Water District of Southern California
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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
ASSOCIATION OF METROPOLITAN WATER AGENCIES
DISINFECTION BY-PRODUCTS IN
UNITED STATES DRINKING WATERS
FINAL REPORT
VOLUME 2- APPENDICES
November 1989
Metropolitan Water District of Southern California
James M. Montgomery, Consulting Engineers, Inc.
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CONTENTS
APPENDIX A
Questionnaire
Cover Letter
APPENDIX B
Sampling Instructions
Sample Information Sheet
APPENDIX C
Analytical Methods
Analysis of Chlorination Disinfection By-Products:
Micro Pentane Extraction
Analysis of Haloacetic Acids: tert-Butyl Methyl
Ether Extraction and Methylation
Analysis of Chioral Hydrate: Micro Methyl
t-Butyl Ether Extraction
Analysis of Cyanogen Chloride: Purge-and-Trap Method
Analysis of Formaldehyde/Acetaldehyde:
Micro Pentane Extraction
APPENDIX D
Correlation Matrices
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JPJI James M. Montgomery
Consulting Engineers. Inc.
a
Appendix A
Questionnaire and Cover Letter
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The Metropolitan Water District of Southern California
March 9. 1988
CERTIFIED MAIL
Contact Name
Utility Name
Utility Street Address
Utility City. State Zip Code
Dear Contact Name:
Increasing attention is being focused on the occurrence of disinfection
by-products (DBPs) due to chlorination in drinking water treatment. These
compounds include not only trihalomethanes. but also haloacetonitriles. haloketones.
haloacids and chlorophenols, among others. The United States Environmental
Protection Agency (EPA) will be developing regulations to control disinfection by-
products as a result of the 1986 amendments to the Safe Drinking Water Act.
Consequently. the Association of Metropolitan Water Agencies (AMWA). in
cooperation with the EPA. is undertaking a study to assess the occurrence of
disinfection by-products and the impact of treatment practices on DBP formation and
control. The Metropolitan Water District of Southern California (MWD) and James
M. Montgomery. Consulting Engineers. Inc. (JMM) will conduct the study.
The specific objectives of the project are: 1) to determine the baseline
occurrence of DBPs at drinking water treatment facilities representing a broad range
of source water qualities and treatment processes: and 2) to determine the effect of
changes in treatment processes and/or disinfectants on the production of DBPs.
Results of this study will be of value to the EPA in defining best available technology
and costs in setting the new regulations. Results will also be of value to the water
utility industry in deciding among treatment process alternatives to meet the new
regulations.
The study will be conducted in two phases. Your involvement would
focus on one of your utility’s treatment plants. Participation in the first phase would
include: 1) completing the enclosed written questionnaire and possibly a telephone
interview. 2) collecting four sets of water quality samples over a period :
(to he analyzed by MWD and JMM laboratories). 3) conducting pH and re4l l
disinfectant measurements on the four sets of samples. and 4) providing some
historical plant data regarding TI-IM levels, chemical closing and any previous pr ss
changes.
In the second phase of the project. a limited number of utilities will he
selected to conduct bench, pilot or full-scale evaluations of the effect of process
modifications on DPB production. If your treatment plant has the capability. such
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The Metropolitan Water District of Southern California
DBP Study -2- March 9. 1988
modifications may include the use of ozonation and/or granular activated carbon
adsorption, or a change of disinfectant. You may choose to participate in either the
first phase or both phases of the project.
The identities of participating utilities would not appear in any published
papers. presentations or press releases, but would be shared on a working basis with
the CDHS.
All DBP data from the MWD and 1MM laboratories pertaining to your
utility will be provided to you. Such data may be useful in assessing your own
treatment practices. You will also receive a copy of the executive summary of the
final project report upon completion of the study.
The analytical methods for the DBPs studied under this project are the
result of an extensive development effort by the U.S. Environmental Protection
Agency. MWD and 1MM laboratories. If you are interested in developing any of the
methods in your own water quality laboratories. MWD and JMM will provide the
methods to you. It is also possible to set up split samples if your laboratory would
like to run quality control checks on the THM or any other DBP analysis conducted
for this study.
The enclosed questionnaire is an integral part of this research effort.
Please provide responses pertaining to only one of the water treatment facilities
operated by your utility, preferably the facility producing the highest levels of
THMs. or a facility producing high THMs that can also accomodate some type of
process modification. If your utility participated in the previously conducted
American Water Works Association Research Foundation THM survey, your
responses on that survey form have been incorporated into the enclosed questionnaire
form. Please double check these entries and make any necessary corrections or
additions.
The results of this effort could influence the outcome of future
regulations. Your input is very important. Please complete the enclosed
questionnaire as soon as possible and return it in the enclosed postage-paid envelope
by March 23, 1988. Thank you for your participation.
Very truly yours.
Michael J. McGuire. Ph.D.
Director of Water Quality
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DISINFECTION BY-PRODUCTS STUDY
QUESTIONNAIRE
Please complete this questionnaire in its entirety. All questions, with the exception
of Questions I through 3, apply only to the specific water treatment facility where
samples will be taken, If certain information and/or data are not available, please
indicate “Not Avail.” If a question does not apply to your utility or water treatment
facility, please mark “N/A” in the space provided. For questions that may require
more space than is provided, please use a separate sheet of paper. Handwritten
responses are preferred to avoid transcription errors during typing.
When completed. please return the questionnaire by April 14, 1988, in the enclosed
postage-paid envelope to:
Dr. Joseph G. Jacangelo
James M. Montgomery, Consulting Engineers, Inc.
250 North Madison Avenue
P.O. Box 7009
Pasadena, California 91109-7009
Should you have any questions about the information requested, please contact either
Joe Jacangelo or Nancy Patania at (818) 796-9141.
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1. Utility name and address:
2. Contact person and telephone number:
3. Size of population served by utility:
Direct retail: Indirect Retail (Wholesale)
Connections_____________ Connections_____________
Population served________ Population served_________
4. Name and address of subject water treatment plant:
5. Source(s) of water supply to subject water treatment plant (please identify each
source by name and whether the source is a flowing stream, groundwater, or
lake/reservoir):
Source Type Name Average % of supply
to this facility
Flowing stream __________________
Groundwater _________________
Lake/reservoir ___________________
Purchased ___________________
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6. Design hydraulic capacity of plant (MGD):
7. Please attach or draw a schematic of the plant showing treatment processes and
locations of chemical addition.
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8. a. Chemical Application (i.e.. oxidant. ozone, permanganate, coagulant, coagulant aid.
powdered activated carbon, filter aid, disinfectant. etc.):
Typical Dosage Typical Detention
Process Chemical ( ppm) Time (mm )
Pretreatment __________________ _____________
Rapid Mix _______________ ___________
Flocculation __________________ _____________
Sedimentation _________________ _____________
Filtration _______________________ _________________
Disinfection ___________________ ______________
Softening
Other __________________ _____________
b. Non-conventional treatment processes (if applicable):
Granular Activated Carbon: Empty Bed Contact Time (mm)
Air Stripping: Air-to-Water Ratio
Ion Exchange: Yes/No
Reverse Osmosis: Yes/No
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9. Water Quality
RAW WATER QUALITY (1987 DATA) TREATED WATER QUALITY (IMMEDIATELY AFTER
FINAL DISINFECTION BUT BEFORE DISTRIBUTION)
(1987 DATA)
Parameter Measured Annual Concentration Measured Annual Concentration
Average Maximum Minimum Average Maximum Minimum
pH (standard pH units) _____________ _____________ __________
Alkalinity (ppm as CaCO 3 ) _____________ ____________ __________
Turbidity (NTU) _____________ _____________ __________
Color (Standard color units) _____________ _____________ __________
Total Organic Carbon (ppm) _____________ _____________ __________
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10. Disinfection and Distribution System:
TREATED WATER QUALITY (IMMEDIATELY AFTER DISTRIBUTION SYSTEM CHARACTERISTICS
FINAL DISINFECTION BUT BEFORE DISTRIBUTION) (1987 DATA)
(1987 DATA)
Parameter Measured Annual Concentration Measured Annual Concentration
Average Maximum Minimum Average Maximum Minimum
Disinfectant Residual
Free Chlorine (ppm Cl 2 ) _____________ _____________ ________
Combined Chlorine (ppm Cl 2 ) _____________ _____________ ________
Chlorine Dioxide (ppm Cl0 2 ) _____________ _____________ ________
(if applicable)
Trihaloine thanes
Total (ppb) _____________ _____________ ________
Chloroform (ppb) _____________ _____________ ________
Dichiorobroinomethane (ppb) _____________ _____________ ________
Dibromochioromethane (ppb) _____________ _____________ ________
Bromoform (ppb) _____________ _____________ ________
Detention time (days)
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11. Has a pilot or bench study on control of THMs or DBPs ever been conducted at
the plant? If yes. please provide information regarding study objectives.
(MWD may request study results at a later time.)
Thank you very much for helping the Association of Metropolitan Water Agencies.
Return the questionnaire in the stamped, self-addressed envelope to:
Dr. Joseph G. Jacangelo
James M. Montgomery, Consulting Engineers. Inc.
250 North Madison Avenue
P.O. Box 7009
Pasadena. California 91109-7009
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JPJdI J èS NA. N1ontqomer
Ccnsu t ng En neers. nc
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Appendix B
Sampling Instructions and
Sample Information Sheet
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To: Participants in Chlorination Disinfection By—Products Study
From: Stuart V. Krasner, Senior Chemist
Metropolitan Water District of Southern California
Subject: Instructions for Collection and Shipment of Water Samples
The samples you are about to collect are for an occurrence and control
study of disinfection by—products which may be formed by the chlorination of your
drinking water. These samples are very important and great care must be used
when collecting and returning them.
Your sampling kit contains:
(1) 22 bottles to fill at the treatment plant clearvell effluent,
(2) 7 bottles (marked with red dots and in a separate bag) to fill at the
influent to the treatment plant (i.e., “raw” water before the addition
of disinfectant/oxidant, coagulant, lime, etc.), and
(3) 3 bottles (in a separate bag) to fill at the filter influent.
(4) Your sampling kit also contains 6 bottles labelled “TRAVEL BLANK”. Do
not open these bottles; just return them with the samples you collect.
Please measure the temperature, pH, and chlorine residual (free and
total) at all three sample points and record the information on the attached
SAMPLE INFORMATION SHEET. If chlorine dioxide is used, please measure its
residual at the three sample points and record as veil. Please fill out the
remainder of the information sheet, INCLUDING MARKING UP THE ATTACHED SCHEMATIC.
Please collect the samples on ___________________, 19
SAMPLING INSTRUCTIONS
1. The sample bottles contained in the accompanying “sampling kit”, and
parameters to be analyzed from each bottle, are as follows:
# & Size of
Parameter Sample Bottle
CLEARWELL EFFLUENT SAMPLE BOTTLES:
Pent. Ext. DBP5* 3 - 40 mL
Chioral Hydrate 3 - 40 niL
Haloacids 4 - 40 niL
Cyanogen Chloride 4 - 40 niL
Formaldehyde 3 - 40 niL
TOX 2-25On iL
TOC 3- 6OmL
PLANT INFLUENT (RAW) SAMPLE BOTTLES:
Formaldehyde 3 - 40 niL
Bromide 1 - 60 niL
TOC 3- 6OmL
FILTER INFLUENT SAMPLE BOTTLES:
TOC 3- 6OmL
ADDITIONAL BOTTLES IN KIT:
Travel Blanks 6 - 40 niL
* Pent. Ext. DBPs = pentane—extractable
disinfection by—products, i.e., trihalomethanes,
haloacetonitriles, haloketones, and chioropicrin.
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2. If the faucet has an aerator, please remove it before collecting the
sample. Let the water run freely from the tap for five minutes before you begin
filling bottles, so you are taking water from the main and not water that has
been settling in the pipes.
3. Slowly fill the sample bottles allowing the water to flow down into the
bottles at a slight angle to reduce the possibility of aerating the sample.
Remove each bottle from the tap when the water reaches the rim. DO NOT RINSE THE
BOTTLES BEFORE FILLING AND DO NOT OVERFILL, SINCE MOST OP THE BU LES CONTAIN A
DECHLORINATION AGE AND/OR PRESERVATIVE.
4. Cap each bottle making certain that the hard shiny Teflon side of the
septum is against the water. Do not overtighten since the caps break easily.
5. Invert each bottle to check for air bubbles.. If air is present, re—open
the bottle and add a few more drops of water. Reseal and check as before.
6. Put each bottle into a separate “bubble—pack” bag and seal the top. Put
the bottles into the ice chest and add two frozen “Blue Ices”. (NOTE: THE “BLUE
ICE” MUST BE PUT IN A FREEZER AT LEAST ONE DAY IN ADVANCE OP SAMPLING.) Cover
with styrofoam packing material so that the bottles will not bounce around during
transit. Please return the SAMPLE INFORMATION SHEET and the marked—up schematic
of your treatment plant in a sealed plastic bag and place in the ice chest.
Close the ice chest and SECURE Vim STRAPPING TAPE.
7. It is essential that the samples are kept cold until we receive them, so
ship the ice chest on the same day the samples are collected via Federal Express
(guaranteed next day delivery). Metropolitan will pay all shipping costs. Use
the enclosed Federal Express airbill. YOU WILL NEED TO CALL FEDERAL EXFKESS
EARLY IN THE DAY TO ARRANGE A PICK-UP TIME TO ENSURE OVERNIGHT DELIVERY.
8. If you have any questions about these sampling and shipping
instructions, please call Stuart Krasner, (714) 392—5083, or Cordelia Hvang,
(714) 392-5126. If there are questions about the source of water or treatment
plant operations for the sampling collection time, please call Joe Jacangelo or
Nancy Patania, (818) 796—9141.
9. We will provide you with results of these measurements at the end of the
project. Thank you very much for your assistance in this matter.
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SAMPLE INFORMATION SHEET
Name of water utility:
Name of water treatment plant:
Source of vater at time of collection:
Sample collection date: ___________
Time of Sampling:
Raw Filter Influent Clearwell Effluent
Name of sampler:
Total chlorine residual:
Raw ______ ppm, Filter Influent ______ ppm, Clearvell Effluent ______ ppm
Free chlorine residual:
Raw ______ ppm, Filter Influent ______ ppm, Clearvell Effluent ______ ppm
Chlorine dioxide residual:
Raw ______ ppm, Filter Influent ______ ppm, Clearvell Effluent ______ ppm
‘Water temperature:
Raw _°F _°C, Filter Influent °F °C, Clearvell Effluent °F °C
pH: Raw Filter Influent Clearwell Effluent
Plant flow at time of sample collection: _______________________________________
PLEASE MARK THE DOSES AND POINTS OP ADDITION OF CHLORINE AND OTHER OXIDANTS/
DISINFECTANTS, PLUS COAGULANTS, USED ON THE SAMPLE COLLECTION DAY ON THE LINES
BELOW AND ON THE ATTAcREU SHEEr, WHICH SHOWS A SCHEMATIC OP YOUR TREATMENT PLANT.
If chioramines are used as a disinfectant, include ammonia dosage and chlorine to
ammonia—nitrogen ratio.
Dose
Location of Addition Chlorine Ammonia Ozone Others (Please Identify )
_____________________ _____ ppm _____ ppm ppm _____________ ppm
____________________ _____ ppm ppm ppm ____________ ppm
_____________________ _____ ppm ppm ppm _____________ ppm
_____________________ _____ ppm ppm ppm _____________ ppm
_____________________ _____ ppm ppm ppm _____________ ppm
_____________________ _____ ppm ppm ppm _____________ ppm
____________________ _____ ppm ppm ppm ____________ ppm
Alum dose _____ ppm
Name and dose of other coagulants and polymers used:
DO NOT WRITE BELOW THIS LINE
MVDSC sample no.: Raw ________ Filter Influent ________ Effluent ________
Date received Time ___________ ReceivedThy _____________________
TOC samples acidified by __________ ________ Date ___________ Time _____
TOX samples dechlorinated/acidified by _______ Date ___________ Time ____
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JMA James M. Montgomery
Consulting Engineers Inc.
I
Appendix C
Analytical Methods
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ANALYSIS OF CHLORINATION DISINFECTION BY-PRODUCTS:
MICRO PENTANE EXTRACTION
1. SCOPE AND APPLICATION
1.1 This method was developed to simultaneously analyze for
the trihalomethanes, haloacetonitriles, chloropicrin,
1,1—dichioropropanone, and 1,1,1—trichioropropanone in
drinking water.
1.2 The experimentally determined method detection limits
were calculated (Table 1). The method has been shown to
be useful for the trihalomethanes (THMs) over a range of
0.1 to 80 micrograms per liter (pg/L) and 0.02 to 20
ug/L for the other disinfection by—products (DBPS).
2. SUMMARY OF METHOD
2.1 Twenty milliliters (mL) of sample is extracted with 4 mL
of pentane with a salting agent to increase the
extraction efficiency. The analysis is conducted on a
gas chromatograph (GC) with subambient temperature
programming and a fused silica capillary column to,
obtain baseline resolution of all the analytes.
Detection is performed with an electron capture detector
(ECD). Aqueous calibration standards are extracted and
analyzed in the same manner as the samples in order to
compensate for extraction efficiency.
3. INTERFERENCES
3.1 Trihalomethane—grade pentane is used to minimize the
contribution of interference from the extraction
solvent.
3.2 Glassware, except volumetric flasks, is cleaned as
follows:
3.2.1 Detergent washed.
3.2.2 Rinsed twice with tap water.
3.2.3 Rinsed twice with deionized water.
3.2.4 Rinsed twice with Millipore Super—Q System
(Bedford, Mass.) water.
3.2.5 Baked in oven at 180°C for one hour; however,
septa are baked at 80°C for one hour.
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3.3 Cleaning procedure for volumetric flasks.
3.3.1 Immediately after use rinse three times with
methanol.
3.3.2 Allow volumetric flasks to air dry in the
ventilation hood for 3 hours.
3.3.3 These flasks are only reused for the preparation
of “pentane—extractable” DBP standards.
4.4. SAFETY
4.1 Chloroform has been identified as a potential carcinogen
and handling is minimized and performed under a
ventilation hood. The toxicity of the other THMs and
DBPs has not been precisely defined; each chemical is
treated as a potential health hazard and handled under a
ventilation hood.
4.2 All Occupational Safety and Health Association (OSHA)
regulations regarding safe handling of chemicals and
laboratory procedures are used in this method.
5. APPARATUS, EQUIPMENT AND MATERIALS
5.1 SAMPLE CONTAINERS — samples are collected in 40—mL
screw—cap vials with Teflon/silicone septa closures.
5.2 EXTRACTION VIALS — Extraction vials are 30 mL (nominal
25 mL) with open—top screw cap and Teflon/silicone septa
closure.
5.3 MICROLITER SYRINGES — 5, 10, 25, 50, 100 and 500
microliter (pL) sizes from Hamiliton Co., Reno, Nev.,
and a 20—mL syringe from Becton—Dickson Co., Rutherford,
N. 3.
5.4 VOLUMETRIC FLASKS — glass stoppered, 5—, 10— and 25—mL.
5.5 MECHANICAL SHAKER — For the pentane extraction process,
a mechanical shaker table is used with the 30—mL vials.
The vials are inserted into a custom—made wooden holding
block (32—vial capacity). The shaker was purchased from
the Eberbach Corp., Ann Arbor, Mich.
5.6 EXTRACT AND STANDARD SOLUTION STORAGE CONTAINERS -
1.5—mL clear—glass, 15—mL and 1—ounce (oz) amber—glass
screw—cap vials with Teflon—lined septa.
5.7 GAS CHROMATOGRAPH — A Varian model 3500 GC (Sunnyvale,
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Calif.), equipped with split/splitless injector,
subambient oven temperature control (with liquid C0 2 ),
ECD, and model 8035 autosampler, is used for the
analysis. See Table 2 for analytical conditions.
5.7.1 The analytical column is a fused silica DB—5 (J&W
Scientific, Inc., Folsom, Calif.) with a 1.0
micron (p) film, internal diameter (ID) of 0.25
millimeters (mm) and 30 meters (m) in length.
5.7.2 A constant current pulse modulated Nickel 63 ECD
with standard size cell is used for detection.
5.7.3 The carrier and make—up gases are high purity
(99.999 percent) grade which pass through
Drierite, molecular seive 5A, activated charcoal,
and finally an oxygen purifying cartridge before
entering the GC. Two—stage metal diaphragm high
purity regulators are used at the compressed gas
sources. Digital flow controllers regulate
carrier gas flow and all gas lines are 1/8 inch
copper tubing which have been acetone—rinsed and
baked before use.
6. REAGENTS AND CONSUMABLE MATERIALS
6.1 REAGENTS
6.1.1 Extraction solvent is Burdick & Jackson (Muskegon,
Mich.) THM analysis grade peritane.
6.1.2 Sodium sulfate is granular (12—60 mesh), “Baker
Analyzed” reagent (Jackson, Tenn.), baked at 400°C
overnight in a stainless steel pan and stored in a
glass desiccator with Drierite.
6.1.3 Acetone for stock standard solutions is Baker
Resi—Analyzed (Phillipsburg, N. J.).
6.1.4 The preservation agent is ammonium chloride,
granular, “Baker Analyzed” reagent (Phillipsburg,
N. J.).
6.2 STANDARD MATERIALS
6.2.1 See Table 3 for source and physical information.
6.2.2 The reference internal standard 1,2—dibromopropane
is 98 percent pure (Chem Services, Inc.,
Westchester, Penn.). The internal standard is
added at the 30 ug/L level in the pentane used for
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extraction.
6.3 REAGENT WATER - Organic—pure water (OPW) is made in the
laboratory by a Corning megapure all—glass distillation
system (model MP3A, Corning, N. Y.). The source water
for the MP3A is purified laboratory water (Super—Q),
which has gone through several stages of cartridge—type
purification to filter and demineralize the water and
trap the organic compounds.
6.4 STANDARD STOCK SOLUTION
6.4.1 Stocks are prepared volumetrically in acetone from
pure standards. Stock I is prepared at approxi-
mately 1000 pg/L for the four THMs and 280 4 ug/L
for the other DBP components (haloacetonitriles,
chioropicrin and halopropanones) as shown in Table
4. The appropriate volume of the pure standard
(Table 4) is delivered by a 25—pL Hamilton gas—
tight syringe into a 25—mL volumetric flask
containing approximately 23 mL of acetone. A
solvent flush technique is used for delivering the
volume by first drawing up 0.5 uL of acetone and
then 1.0 uL of air before measuring the volume of
each component. The solution is diluted to final
volume with acetone, stoppered and mixed by
inverting the flask several times. Stock I is
transferred into a clean l—oz amber—glass storage
bottle with Teflon—faced septa and screw cap and
stored at 4°C. Stock I is prepared fresh every 3
months.
6.4.2 A secondary stock standard (Stock II) is prepared
by diluting 200 pL of Stock I into a 10—mL
volumetric flask with acetone (Table 4). This
results in concentrations of approximately 20 pg/L
for the THMs and 5 pg/L for the other DBPs. The
solvent flush technique with a gas—tight syringe
is used. The solution is prepared each time a new
set of calibration standards are prepared.
6.4.3 A spike solution is prepared by diluting 250 uL of
a THM only stock (approximately 1000 mg/mL) and
250 1 uL of Stock I into a 5—mL volumetric flask
with acetone (Table 5). The THN only stock is
used to create a wider concentration differential
between the THMs and the other DBPs in the spiked
sample. The spike solution should have a
concentration of approximately 100 ug/mL for the
THMs and 14 pg/mL for the other DBP5. This will
provide a spike sample concentration that is
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similar to that which is found in the unspiked
samples. The spike solution is prepared every 2
weeks.
7. SAMPLIE COLLECTION, PRESERVATION, AND STORAGE
7.1 SAMPLE COLLECTION
7.1.1 Collect all samples in triplicate.
7.1.2 The sampling tap is allowed to flush for approxi-
mately 5 minutes to allow the water temperature to
stabilize and the stagnant lines to be flushed.
7.1.3 Samples are collected in nominal 40—mL vials with
Teflon—faced septa and screw caps. The sample
vials are filled such that no air bubbles pass
through the sample. The bottles are not rinsed
before filling and are not allowed to overfill,
since the bottles contain a preservative. The
sample vials are sealed headspace free.
7.2 SAMPLE PRESERVATION
7.2.1 Ammonium chloride (NH 4 C1) is used as the
preservative agent. The ammonium chloride acts as
a preservative by forming monochloramine in the
presence of free chlorine; monochloramine does not
react with humic or fulvic acids to form the
“pentane—extractable” DBPs during established
holding times under refrigerated temperatures
(4°C).
7.2.2 Approximately 65 mg of crystalline NH 4 C1 is added
to each vial prior to sampling.
7.3 SAMPLE STORAGE
7.3.1 Samples and sample extracts are stored at 4°C
until analysis. Analyses should be performed as
soon as possible after collection and at least
within 48 hours, as trichioroacetonitrile (TCAN)
drops to approximately 50 and 40 percent of its
initial value after 24 and 48 hours, respectively.
The THMs are stable for 2 weeks.
8. CALIBRATION AND STANDARDIZATION
8.1 Aqueous calibration standards are prepared in OPW by
injecting the correct amount of stock standard solution
directly into water using the solvent flush technique.
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8.2 Twelve different concentration levels (from 0.1 to 80
,ug/L for the THMs and 0.02 to 20 4 ug/L for the other
DBPs) are prepared in 160—mL crimp—top bottles
containing 120 mL of OPW. Twenty—four mL of pentane,
containing the internal standard, are placed on top of
the OPW. Each bottle is spiked with the appropriate
volume of the stock solutions (see Table 6). The spike
volume should not exceed 5 pL per 20 mL of water because
of possible solvent interference problems. Thirty grams
of baked sodium sulfate are poured into each bottle from
a plastic weigh boat and the bottle is sealed with a
Teflon—lined septum crimp top. The bottle is laid on
its side until ready for shaking. After all the levels
have been prepared, the bottles are placed in a bottle
holder and shaken for 15 minutes in a mechanical shaker.
The pentane extract is transferred evenly between
fourteen 1.5—mL vials using a disposable pasteur
pipette.
8.3 The standards are prepared in batch ( 120—mL volume) as
opposed to the individually prepared (20—mL volume)
samples so standard extracts can be stored and do not
have to be prepared every day. To verify that the batch
prepared standards were equivalent to standards prepared
individually, three concentrations of batch and
individually prepared standards were compared. Table 7
shows acomparison of area counts obtained for the two
methods of standard preparation. The results show that
both methods of standard preparation are equivalent.
The standards are prepared fresh at least every 21 days.
8.4 A set of standards in the range of 0.1 to 80 ug/L for
the THMS and 0.02 to 20 pg/L for the other DBP5 (see
Table 6 for the actual concentrations) is analyzed by GC
before the samples are analyzed. An external standard
method is used to determine the concentration of the
samples. The internal standard is not used in the
quantitation but is used as a reference peak for peak
identification and as an indicator of injection
errors (see Section 9.2.3). A plot of area versus
concentration (in ug/L) is prepared by using a point—to—
point fit passing through zero. Calculations are made
from only the linear portions of the curve. If the
sample runs extend over 2 days, another set of standards
are injected at the end of the run. Solvent blanks are
run after the standards.
9. QUALITY CONTROL
9.1 MONITORING FOR INTERFERENCES
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9.1.1 Laboratory reagent blanks — A laboratory reagent
blank is analyzed each day to check for any
interferences.
9.1.2 Travel blanks for each sampling location are
prepared in the laboratory by filling 40—mL vials,
as described above (see Section 7.2.2), with OPW.
These are shipped to the sampling site and back to
the laboratory with the sample bottles.
9.1.3 Each reagent bottle of pentane is analyzed before
it is used.
9.2 QUALITY ASSURANCE/QUALITY CONTROL PROTOCOL
The Quality Assurance/Quality Control (QA/QC) protocol
covers accuracy, precision, independent verification and
the use of an internal standard. Accuracy is dependent
on many factors, but the most important is the
calibration curve. Accuracy is monitored by calculating
the recoveries of samples which have been enhanced with
known concentrations of the compounds of interest.
Precision is another parameter that is dependent on more
than one factor. The precision of a method is monitored
by analyzing samples in duplicate and calculating the
normalized difference between the two analyses.
Independent verification of a method is done by
analyzing QC check samples and interlaboratory
calibration. The internal standard is used to insure
that the GC makes consistent injections of samples and
standards.
All of the above mentioned parameters are important in
assuring that good quality data are produced. It is
important to note that all portions of a QA/QC program
must meet the established standards in order for an
analysis to be considered in control.
9.2.1 Method Detection Limits
Initial calculations of the method detection
limits (MDL5) are made according to the Code of
Federal Regulations 40 part 136, July 1, 1987. A
set of 7 standards are prepared in OPW at 1 to 5
times the estimated detection limit. Each
standard is analyzed according to the method and
the standard deviation of the 7 replicate
measurements for each analyte is determined. The
MDL is determined for each analyte as follows:
MDL = t (5)
-------
t = 3.143 (student t value for 6 degrees of
freedom and 99 percent confidence level)
S = standard deviation of the 7 replicate analyses
These MDLs are used as minimum reporting levels
(MRLS), except where the instrumental detection
limit has proved to be higher. Often, the MRL5
correspond to the lowest level standard on the
calibration curve.
9.2.2 Calibration Curves
Quantitation is done using an external standard
calibration curve. Standards are prepared in OPW
spiked with DBPs and extracted with the same
solvent as that used for the samples (see Section
8). The extracted standards are used to
compensate for the varying extraction efficiencies
of the different compounds in the analysis. A
12—point calibration curve encompassing the 0.1 to
80 pg/L range for the TRMS and 0.02 to 20 ug/L for
the other DBPs are used and the 12 standards are
analyzed each day prior to the analysis of the
samples.
9.2.2.1 Acceptance/Rejection Criteria
The curve is determined acceptable if the
fit is smooth. Also, the new calibration
curve is compared to the previous curve
to insure that they are comparable. The
injection is determined to be acceptable
if the internal standard is acceptable
(see Section 9.2.3). All internal
standard area counts ( uV/seconds) should
be within +/— 10 percent for all
standards in the calibration curve.
9.2.2.2 QC Corrective Action
The problem is determined and corrected.
The calibration curve is re—analyzed on
the GC. If re—analysis does not produce
a satisfactory curve, then a new set of
calibration standards are prepared. The
standards are re—analyzed until an
acceptable curve is obtained. All sample
extracts are re—analyzed from the last
point where calibration curves were in
control. The corrective action is
documented in the DSP notebook and signed
by the immediate supervisor and QC
—8—
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officer.
9.2.3 Internal Standard
The internal standard (1,2—dibromopropane) is
spiked directly into each new bottle of solvent at
a concentration of 30 pg/L. The solvent is then
used to extract both samples and calibration
standards. The purpose of the internal standard
is to monitor injections made by the autosampler.
9.2.3.1 Acceptance/Rejection Criteria
A sample injection is deemed acceptable
if the area counts (pV/seconds) of the
internal standard peak do not vary more
than +/— 10 percent from other samples
which are extracted using the same bottle
of solvent on the same date. The
internal standard areas of samples can
not be compared to those of calibration
standards when the samples and standards
are prepared using extraction solvent
from different bottles or on different
days. The internal standard area can
vary from bottle to bottle and day to
day.
9.2.3.2 Corrective Action
The problem is determined and corrected.
The sample extracts are re—analyzed. If
reanalysis is not acceptable, then the
samples are re—extracted and re—analyzed.
If the re—extracted samples are not
acceptable or the samples have exceeded
the holding time, then the samples are
re—sampled and re—analyzed or the results
are recorded as suspect and out of
control. Such data will not be entered
into the database. The corrective action
is documented in the DBP notebook and
signed by the immediate supervisor •and QC
officer.
9.2.4 Spikes
Sample spikes are analyzed to monitor the
extraction efficiency of specific analytes in
sample matrices. This measures the accuracy of
the method in a natural matrix. The spiked
samples are analyzed at a frequency of at least 10
percent of the samples. The spike solution is
prepared in acetone (Table 5). The samples are
spiked with 4 pL of spike solution to acheive a
—9—
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concentration of 20 pg/L for THMs and 3 pg/L for
other DBPs, which are the levels that are
typically found in samples. The spike volume must
not exceed 5 pL per 20 mL of sample because of
possible solvent interference problems. Data are
entered into the QC table directly after the
analysis. The QC charts are reviewed by the
analyst and the immediate supervisor.
9.2.4.1 Acceptance/Rejection Criteria
All spike recoveries must fall within the
upper and lower control limits to be
acceptable. Initial control limits are
defined by calculating the mean percent
recovery from the most recent 50 sample
spike data points. The 99 percent
confidence interval is +/— three times
the standard deviation. Warning limits
are defined as +/— two times the standard
deviation. If a sample recovery is above
or below the warning limit this indicates
there is a potential problem. The
problem is determined and corrected
before the analysis is out of control.
Control limits and warning limits are re-
calculated on a semiannual basis using
the most recent 50 spiked sample percent
recovery values. Data points that are
out of control are not included in the
re—calculation of new control limits.
Control limits are re—calculated when any
major changes are made in the analytical
procedure (i.e. new type of column) and
after at least 20 points have been
collected.
9.2.4.2 QC Corrective Action
The problem is determined and corrected.
The sample extracts and spiked sample
extract are re—analyzed from the point
where the last sample spike recovery was
in control. If the spike recovery is
still not acceptable, then the samples
are re—extracted from the point where the
last spike was in control and a sample is
re—spiked and re—analyzed only for those
analytes that are out of control. If the
spike recovery is not acceptable or
samples have exceeded the holding time,
then the samples are re—sampled and re-
analyzed from the point where the last
—10—
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spike was in control. A sample is re—
spiked and re—analyzed. If re—analysis
is not possible the results are recorded
as suspect for only those analytes that
are out of control. Such data will not
be entered into the database. The
corrective action is documented in the
DBP notebook and signed by the immediate
supervisor and QC officer.
9.2.5 Duplicates
Sample duplicates are analyzed in order to monitor
the precision of the method. Duplicates are
analyzed on randomly selected samples at a
frequency of at least 10 percent of the samples.
Data are entered into the QC table within 24 hours
after the analytical run is completed. The QC
charts are reviewed by the analyst and the
immediate supervisor.
9.2.5.1 Acceptance/Rejection Criteria
Control limits are determined by
calculating the range as a function of
the relative standard deviation
(coefficient of variation) as specified
in Standard Methods proposed method
1020B. The range (R) is calculated by
taking the absolute difference of the
duplicate values as follows:
R = Ixi—x 2 1 (x 1 and x 2 are the duplicate
values)
The normalized range (Rn) is calculated
by dividing the range (R) by the average
of the duplicate values (xm):
Rn R
Xm
X 1 + X 2
Xm =
2
A mean normalized range (Rm) is
calculated for 50 pairs of duplicate data
points:
Rm =
n
—11—
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n = number of duplicate pairs
The variance (s 2 ) of the normalized
ranges is calculated:
E(R - Rm) 2
n—i
The standard deviation (s) is calculated
as the square root of the variance.
The upper and lower control limits are
defined as Rm + 3s and zero,
respectively. All duplicates must fall
within the control limits to be
acceptable. The upper warning limit is
defined as Rm + 2s. If an Rn is outside
the warning limit, this indicates there
is a potential problem. The problem is
investigated before the analysis is out
of control. Control limits are
recalculated on a semiannual basis using
the most recent 50 points. Data points
that are out of control are not included
in the recalculation of new control
limits. Control limits are recalculated
when any major changes are made in the
analytical procedure (i.e. new type of
column) and after at least 20 points have
been collected.
9.2.5.2 QC Corrective Action
The problem is determined and corrected.
The sample extracts and the duplicate
extracts are re—analyzed from the point
where the last sample duplicate was in
control. If the duplicate is still not
acceptable, then the samples are re—
extracted from the point where the last
duplicates were in control and a
duplicate is re—analyzed only for those
analytes that were out of control. If
the duplicates are still unaccr?pt h1 or
the sample holding time has been
exceeded, then the samples are re—sampled
and re—analyzed from the point where the
last duplicates were in control. A
duplicate is re—analyzed. If this is not
possible the results for only those
analytes that were out of control are
—12—
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recorded as suspect. Such data will not
be entered into the database. The
corrective action is documented in the
DBP notebook and signed by the immediate
supervisor and QC officer.
9.2.6 Check Samples
The check samples are used to provide an
independent confirmation of the accuracy of the
method. Check samples are only available for
triha].omethanes (THM5) at the present time. There
are many adequate sources of check samples, but
the EPA is the best source. The mean, standard
deviation, and 95 percent confidence interval for
laboratories who have previously analyzed the
samples are provided. This gives the added
benefit of comparing the results against those of
other laboratories. The THM check samples are
analyzed quarterly.
9.2.6.1 Acceptance/Rejection Criteria
The 95 percent confidence interval that
is provided by the EPA for each set of
THM QC check samples is used as the
acceptance limit. However, once enough
data are accumulated on QC check samples
analyzed in the laboratory, control
limits will be established using the
guidelines in section 9.2.4, based on at
least 20 data points. All samples must
be within control limits to be
acceptable.
9.2.6.2 QC Corrective Action
The problem is determined and corrected.
If the problem is determined to be with
the check sample spiking and the sample
spikes and duplicates are in control, it
is only necessary to re—analyze the check
sample extract. However, if the problem
is more widespread, then it is necessary
to re—analyze the check sample extract
and those sample extracts which were
analyzed with it. If the re—analysis is
not acceptable then the check sample is
re—analyzed until acceptable and the
samples that were analyzed with the check
sample are re—analyzed. If the check
sample is still not in control or the
holding time is exceeded for those sample
extracts analyzed with the check sample,
—13—
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then the samples are re—sampled and
re—analyzed or the results for only those
analytes that are out of control are
recorded as suspect. Such data will not
be entered into the database. The
corrective action is documented in the
DSP notebook and signed by the immediate
supervisor and QC officer.
9.2.7 Interlaboratory Calibration
Samples will be split and sent to another
laboratory that is experienced in DBP analysis
when available. This will allow the comparison of
results with another laboratory. This will
provide another means of independent verification.
When split samples are sent a QC check sample and
DSP spiked sample will also be sent to verify the
quality assurance of the other laboratory.
Results will be recorded in the DBP notebook.
10. PROCEDURE
10.1 SAMPLE PREPARATION
10.1.1 Samples and standards are removed from storage
and allowed to reach room temperature.
10.2 MICROEXTRACTION AND ANALYSIS
10.2.1 A 20—mL aliquot of sample water is withdrawn
from the sample container by a 20—mL glass
syringe and delivered to a 30—mL vial with
Teflon—faced septum and screw cap.
10.2.2 A 4—mL volume of pentane (containing the
internal standard) is added to the vial by a
Brinkman Dispensette and the vial is capped.
10.2.3 After all the vials are filled, S gm of sodium
sulfate is measured, using a custom—made “5 gm”
stainless—steel scoop, and poured into each
vial. The vial is capped immediately, shaken by
hand for several seconds to break up the clumps
of sodium sulfate.
10.2.4 After all the vials have been sealed and
prepared for extraction, they are placed in a
vial holder and shaken for 5 minutes in a
mechanical shaker.
10.2.5 The vials are removed from the vial holder,
placed upright and allowed to stand for 5
—14—
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minutes. Equal volumes of extract are
transferred into two l.5—mL vials by a pasteur
pipet.
10.2.6 At the beginning of each analytical run, a
pentane solvent blank is injected to condition
the GC and to verify that no interferences are
present.
10.2.7 The data are collected on a Hewlett Packard
model 300 microcomputer (Palo Alto, Calif.) with
Nelson Analytical Xtrachrome chromatography
software (Cupertino, Calif.). Autosampler
information (rack# & vial#) is communicated to
the data system for sample identification
purposes. The data files are designated WFXXXXY
where WF is a code designating the pentane—
extractable DBP analysis, XXXX is the month and
day in numbers and Y is a unique sequential
cycle number assigned to each data file by the
data system. The data files are archived to
magnetic tape.
10.2.8 See Table 1 for retention times.
—15—
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TABLE 1
METHOD DETECTION LIMITS (MDLs),
MINIMUM REPORTING LEVELS (MRLs),
AND RETENTION TIMES (RTs)
MDLs MRLs RTs
Compounds ( ug/L) ( .ug/L) ( mm )
Chloroform (CHC1 3 ) 0.02 0.1 7.57
Bromodichioromethane (CHC1 2 Br) 0.02 0.1 14.25
Dibromochioromethane (CHC1Br 2 ) 0.02 0.1 22.81
Bromoform (CHBr ) 0.01 0.1 26.68
Trich].oroacetonitrile (TCAN) 0.01 0.03 11.55
Dichioroacetonitrile (DCAN) 0.02 0.03 15.77
Bromochioroacetonitrile (BCAN) 0.04 0.04 23.76
Dibromoacetonitrile (DBAN) 0.08 0.08 27.39
1,1—Dichioropropanone (1,1—DCP) 0.03 0.03 17.61
1,1, 1—Trichioropropanone
(1,1,1—TCP) 0.01 0.03 25.15
Chioropicriri (CHP) 0.01 0.03 22.13
1, 2_Dibromopropanea 25. 59
alnternal standard.
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TABLE 2
GAS—CHROMATOGRAPHIC CONDITIONS
Column
Type: Fused silica capillary
(Durabond—5, J&w Scientific, Folsom, Calif.)
Length: 30 meters
Internal diameter: 0.25 millimeters
Film thickness: 1.0 micron
Temperature program (subambient with liquid C0 2 ):
17°C > 29°C > 110°C > 204°C
1.11 mm 3°C/mm 13 mm 9°C/mm 0 mm 27°C/mm 2 mm
Injector
Injection volume: 2 pL
Temperature: 177°C
Splitless injection: Split valve opened at 0.5 mm
Detector
Type: Electron capture
Temperature: 272°C
Gases
Carrier: Helium (99.999percent purity)
Flow: 1.5 mL/min at 25°C
Makeup: Nitrogen (99.999 percent purity)
Flow: 24 mL/min
Autosampler Parameters — (for Varian model 8035 autosampler)
Purge pulse pressure 55 psi
Number of purge
pulses 1
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TABLE 3
ANALYTICAL STANDARDS
Molec— Boiling
Purity ular Point
Compound Source ( percent) Weight ( °C) Density
CHC 1 3 Aidricha 99+ 119 61 1.492
CHC 1 2 Br Chem svcb 98.5 164 87 1.980
CHC1Br 2 Chem Svc 98+ 208 119 2.451
CHBr 3 Chem Svc 98 253 151 2.894
TCAN Pfaltz 144 86 1.4403
DCAN Pfaltz 95 110 110—112 1.369
BCAN Columbi ac 154 125—130 1.680
DBAN Pfaltza 95 199 70—72 2.369
CHP Kodake 164 112 1.6483
1,1—DCP Aldrich 98 127 120 1.327
l,l,1—TCP Aldrich 99.4 161 149 1.435
aAldrich Chemical Company, Inc., Milwaukee, Wisc.
bchem Service, Inc., Westchester, Penn.
CColumbja Organic Chemical Company, Inc., Camden, S. C.
dpfaltz & Bauer, Inc., Waterbury, Conn.
eEastman Kodak Company, Rochester, N. Y.
TABLE 4
DBP STOCK SOLUTION CONCENTRATIONS
Stock I Stock 1 1 b
Compound ( pLd) ( mg/L) ( mg/L )
CHC1 3 17 1015 20.3
CHC1 2 Br 13 1030 20.6
CHC1Br 2 11 1078 21.6
CHBr 3 9 1042 20.8
TCAN 5 288 5.76
DCAN 5 274 5.48
BCAN 4 269 5.38
DBAN 3 284 5.69
CHP 4 264 5.27
1,l—DCP 5 265 5.31
1,1,1—TCP 5 287 5.74
aVolume of pure compound spiked into 25 mL of acetone.
b 200 pL of stock I spiked into 10 mL of acetone.
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TABLE 5
SPIKE SOLUTION AND SAMPLE SPIKE CONCENTRATIONS
Spike
THM* Solution** Spike***
Stock Stock Sample
Compound mg/L mg/L pg/L
CHC 1 3 1015 101 20.3
CHC1 2 Br 3 1030 103 20.6
CHC1Br 2 1078 108 21.6
CHBr 3 1042 104 20.8
TCAN 14.4 2.88
DCAN 13.7 2.74
BCAN 13.4 2.69
DBAN 14.2 2.84
CHP 13.2 2.64
1,1—DCP 13.3 2.65
1,1,1—TCP 14.4 2.87
* A THM stock is prepared in acetone with the same volumes of
THMs as specified for Stock I (Table 4).
** Prepared by adding 250 1 uL of Stock I (Table 4) and 250 pL of
THM stock to S mL of acetone. The TIIM stock is used to
create a wider concentration differential between the THMS
and the other DBPs in the spiked sample.
*** Add 4 pL of spike solution to 20 mL of sample.
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TABLE 6
CONCENTRATION OF DBPS IN CALIBRATION STANDARDS (pg/L)
aVolua. of stock spiked into 120
syringe us.d.
dO_ /IL syringe used.
d 25 _PL syringe used.
mL of OPW.
Stock II
Stock I
0.101
0.103
0.108
0.104
0.0288
0.0274
0.0269
0.0284
0.0264
0.0265
0.220
0.223
0.234
0.226
0.0624
0.0593
0.0582
0.0616
0.0571
0.0575
0.541
0.549
0.575
0.556
0.154
0.146
0.143
0.152
0.141
0.142
Level:
1
2
3
4
5
6
7
8
9
10
11
12
Stock vol—
um. 5 (pL):
0 6 b
1 3 b
32 b
64 c
13 d
06 b
13 b
24 b
36 c
48 c
72 c
95 d
Compound
CHC1 3
CHC1 2 Br
CHC1B r 2
CHBr 3
TCAN
DCAN
B CAN
DBAN
CH P
1, 1—DCP
1,1 , 1—
TCP
0.0287 0.0622 0.153
0.306
0.622
1.44
3.11
5.74
8.61 11.5
17.2
22.7
1.08
1.10
1.15
1.11
0.307
0.292
0.287
0.303
0.281
0.283
2.20
2.23
2.34
2 .26
0.624
0 .593
0.582
0.616
0.571
0.575
5.07
5.15
5.39
5.21
1.44
1.37
1.34
1.42
1.32
1.33
11.0
11.2
11.7
11.3
3.12
2.97
2.91
3.08
2.86
2.88
20.3
20.6
21.6
20.8
5.76
5.48
5.38
5.69
5.27
5.31
30.4
30.9
32.4
31.3
8.64
8.21
8.06
8.53
7.91
7.96
40.6
41.2
43.1
41.7
11.5
11.0
10.8
11.4
10.6
10.6
60.9
61.8
64.7
62.5
17.3
16.4
16.1
17.1
15.8
15.9
80.3
81.5
85.4
82.5
22.8
21.7
21.3
22.5
20.9
21.0
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COMPARISON OF AREA FOR BATCH-EXTRACTED VERSUS
INDIVIDuAF T STANDARDS
0.5—jig/L Standard 20-ug/L Standard
Zof Zof
Compound Batcha Ind ’ D1f md. Diff Batch md. Diff
CHC]. 3 7.5 7.2 83.9 6 433 392 10
CHC1 2 Br 575 573 805 6 2618 2623 <1
CHC1Br 2 52.3 52.0 730 5 1846 1863 1
CHBr 3 18.2 17.9 198 6 899 912 1
TCAN 114 114 1533 3 3562 3572 <1
DCAN 46.0 474 564 1 2647 2686 1
BCAN 33.8 35.2 516 1 1520 1550 2
DBAN 28.5 30.2 430 3 1373 1405 2
CHP 109 108 1297 3 2779 2817 1
1,1—DCP 29.5 30.7 318 2 1801 1838 2
1,1,1—TCP 59.5 60.3 768 4 1782 1803 1
*Area counts in the thou e., area count of 7.5 is actually 7,500.
aBatch: GC area counts batch—extracted standards.
blndividual: Average GCIfltS of 2O-mL individual extraction
(three replicates).
C% of Diff: Percent of (Ce between batch and individual counts.
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ANALYSIS OF HALOACETIC ACIDS:
tert-BUTYL METHYL ETHER EXTRACTION AND METHYLATION
1. SCOPE AND APPLICATION
1.1 This method was developed to simultaneously analyze for
monochioroacetic acid, monobromoacetic acid,
dichloroacetic acid, trichioroacetic acid, dibromoacetic
acid, and 2,4,6—trichlorophenol in drinking water.
1.2 The experimentally determined method detection limits
were calculated (Table 1). The method has been shown to
be useful for the haloacetic acids (HAAs) over a working
range of 0.5 to 30 micrograms per liter ( 4 ug/L) (1.0 to
30 Mg/L for monochloroacetic acid) and 0.25 to 15 pg/L
for 2,4,6—trichlorophenol. The calibration range can
be extended depending on the compound and detector
characteristics.
2. SUMMARY OF METHOD
2.1 Twenty milliliters (mL) of sample is extracted with 5 mL
of tert—butyl methyl ether (tBME) at an acidic pH (in
order to extract the nondissociated acid) and with a
salting agent (to increase the extraction efficiency).
The extract is subjected to esterification using
diazomethane solution in order to produce chromato—
graphable methyl ester derivatives. The analysis is
conducted on a gas chromatograph (GC) with temperature
programming and two fused silica capillary columns to
obtain baseline resolution of all the analytes on an
analytical and a confirmation column. Detection is
performed with two electron capture detectors (ECDs).
Aqueous calibration standards are extracted, esterified,
and analyzed in the same manner as the samples in order
to compensate for extraction efficiency.
3. INTERFERENCES
3.1 HPLC—grade tBME is used to minimize the contribution of
interference from the extraction solvent.
3.2 All glassware, except volumetric flasks and diazomethane
generators, use the following cleaning procedure.
3.2.1 Detergent wash (Liquinox detergent, Alconox,
Inc., New York, N. Y.).
3.2.2 Rinse twice with tap water.
3.2.3 Acid rinse (except for sample collection vials)
with 1:10 hydrochloric acid (HC1).
—1—
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3.2.4 Rinse twice with deionized water.
3.2.5 Rinse twice with Millipore Super —Q System
(Bedford, Mass.) water.
3.2.6 Bake in annealing oven at 400°C for 30 minutes
(cover tops and openings with aluminum foil
before baking); however, bake sample collection
vials in an oven at 180°C for one hour.
3.3 cleaning procedure for diazomethane generators.
3.3.1 Immediately after use rinse inner tube twice with
5.0 N sodium hydroxide (NaOH), then rinse twice
with tap water.
3.3.2 Immediately after use add 1 gm of silica gel to
the outside tube to quench any residual
diazomethane solution, then rinse twice with
methanol and twice with tap water.
3.3.3 Subsequently, rinse both inner and outside tubes
twice with 5.0 N NaOH.
3.3.4 Rinse with deionized water.
3.3.5 Rinse twice with 25% lid solution.
3.3.6 Rinse with deionized water 3 times.
3.3.7 Bake at 130°C for at least 2 hours in a clean,
forced—air convection oven.
3.4 Cleaning procedure for volumetric flasks.
3.4.1 Immediately after use rinse three times with
methanol. Invert them to drain on a rack.
3.4.2 Allow volumetric flasks to air dry in the
ventilation hood for 3 hours.
3.4.3 These flasks are reserved for the preparation of
haloacetic acid standards only.
3.5 Cleaning procedure for all caps, septa, and Teflon
stopcocks.
3.5.1 Rinse with acetone once.
3.5.2 Rinse with hexane once.
—2—
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3.5.3 Rinse with acetone once.
3.5.4 Bake at 80°C for not more than 1 hour in a clean,
forced—air convection oven.
4.0 SAFETY
4.1 The toxicity and carcinogenicity of all the chemicals
used in this method have not been fully identified;
therefore, each chemical is treated as a potential
health hazard. Thus any exposure to these chemicals is
minimized, and they are only used in a properly
operating ventilation hood.
4.2 All Occupational Safety and Health Association (OSHA)
regulations regarding safe handling of chemicals and
laboratory procedures are used in this method.
4.3 MNNG (l—methyl—3—nitro—1—nitrosoguanidine) is
carcinogenic.
4.3.1 The MNNG is stored in plastic containers
containing activated carbon in a refrigerator
used only for chemical storage.
4.3.2 Spatulas and glassware for the handling of MNNG
are stored in specially labelled plastic
containers and only used for that purpose.
4.4 Diazomethane is toxic, carcinogenic and an explosion
hazard. Special precautions must be followed whenever
handling this material.
4.4.1 Use only in a properly operating fume hood — do
not breath vapors.
4.4.2 Transfer solutions using only mechanical
pipetting techniques.
4.4.3 Do not heat above 90°C to avoid explosions.
4.4.4 Do not use glassware with grinding surfaces
(e.g., ground glass joints, sleeve bearings) or
glass stirrers to avoid explosions. Special
glassware for diazomethane generation and
handling, as well as screw—cap volumetric flasks,
are commercially available.
4.4.5 A safety shield must be used when generating
diazomethane.
4.4.6 Excess diazomethane must always be quenched with
silica gel.
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4.5 Safety requirements for ether.
4.5.1 Store ether in tightly—closed, amber bottles in
an explosion—safe or —proof refrigerator.
4.5.2 Store only with compatible chemicals.
4.5.3 Ether is extremely flammable; all sources of
ignition shall be eliminated. Keep away from
heat, sparks and flames.
4.5.4 Ether can cause eye irritation and dermatitis;
handle only in a hood and avoid direct physical
contact.
4.5.5 Ether can cause headaches, dizziness, nausea or
unconsciousness — do not breathe vapors.
4.5.6 Spills or leaks require evacuation of area, then
ventilate and absorb on vermiculite or similar
material. Wear appropriate OSHA equipment before
entering spill area.
4.6 Explosion—safe or —proof refrigerator/freezer.
4.6.1 Ether extracts with diazomethane solution (during
esterification step, see Section 10.4.4) must be
stored in an explosion—safe or —proof
refrigerator.
4.6.2 Ether extracts must be stored in an explosion—
safe or —proof freezer.
4.6.3 Most laboratory refrigerator/freezers are not
explosion—safe or —proof; although, explosion—
safe and —proof units are commercially available.
5. APPARATUS, EQUIPMENT AND MATERIALS
5.1 SAIIPLE CONTAINERS — samples are collected in 40-mL screw
cap vials with Teflon/silicone septa closures.
5.2 EXTRACTION VIALS — Extraction vials are 40—mL volume
with open—top screw cap and Teflon/silicone septa
closure (same as sample containers).
5.3 NICROLITER SYRINGES — 5, 10, 25, 50, 100, 500 and 1000
microliter (pL) sizes from Hamiliton Co., Reno, Nev.,
and a 20—mL all—glass syringe (Becton—Dickson Co.,
Rutherford, N. J.).
5.4 MICRO VOLUMETRIC FLASKS — Teflon—lined screw—cap: 2—mL,
5—mL and l0—mL (Kontes Scientific Glassware, Vineland,
N. J.).
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5.5 MECHANICAL SHAKER — For the tBME extraction process, a
mechanical shaker table is used with the 40—mL vials.
The vials are inserted into a custom—made wooden holding
block (20 vial capacity). The shaker was purchased from
the Eberbach Corp., Ann Arbor, Mich.
5 .6 EXTRACT AND STANDARD SOLUTION STORAGE CONTAINERS -
1.8—mL clear glass, 7— and 14—mL amber glass screw—cap
vials with Teflon—lined septa.
5.7 GAS CHROMATOGRAPH - A Varian model 3400 GC equipped with
split/splitless injector (using a straight open bore
insert), two ECDs, and model 8035 autosampler, is used
for the analysis. See Table 2 for analytical
conditions.
5.7.1 The analytical column is a fused silica DB—1701
(J&W Scientific, Inc., Folsom, Calif.) with a
0.25 micron (ii) film, internal diameter of 0.25
millimeters (mm) and 30 meters (m) in length.
The confirmation column is a fused silica DB—5
(J&W Scientific, Inc.) with a 0.25 p film,
internal diameter of 0.25 mm and 30 m in length.
5.7.2 A constant current pulse modulated Nickel 63 ECD
with standard size cell is used for detection.
5.7.3 The carrier and make—up gases are high purity
(99.999 percent) grade which pass through
Drierite, molecular seive 5A, activated charcoal,
and finally an oxygen purifying cartridge before
entering the GC. Two—stage metal diaphragm high
purity regulators are used at the compressed gas
sources. Digital flow controllers regulate
carrier gas flow and all gas lines are 1/8 inch
copper tubing which have been acetone—rinsed and
baked before use.
6.0 REAGENTS AND CONSUMABLE MATERIALS
6.1 REAGENTS
6.1.1 Extraction solvent is Aldrich HPLC—grade 99+%
tert—butyl methyl ether (Milwaukee, Wisc.)
6.1.2 Sodium sulfate is granular, “Baker Analyzed”
reagent, suitable for pesticide analysis
(Jackson, Tenn.). Heat treat at 400°C overnight
in a shallow stainless steel pan covered with
pierced aluminum foil. Store in a l—L glass
—5—
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bottle with Teflon—lined polypropylene cap
(Wheaton, Niliville, N. J.).
6.1.3 Acidified sodium sulfate — Weigh out 1000 gm of
baked sodium sulfate and add enough methylene
chloride (-375—400 mL) to make a slurry. While
stirring continuously, add slowly 3 mL of
concentrated sulfuric acid and leave in a well—
ventilated hood, allowing the solvent to
evaporate completely with occasional stirring.
Test for acidity by mixing 1 gm of salt with 5 mL
of distilled water and measure the pH of the
mixture to ensure that it is below 4. After
checking the pH level, dry the acidified salt in
a 130°C oven overnight. Store in a 1—L glass
bottle with a Teflon—lined polypropylene cap.
6.1.4 Methanol for stock standard solutions is Baker
Resi—Analyzed (Phillipsburg, N. J.).
6.1.5 The preservation agent is ammonium chloride,
Fischer Scientific (Pittsburg, Penn.), USP/FCC
grade.
6.1.6 Sodium hydroxide solution — Prepare a 20%
solution using ACS low carbonate grade pellets.
Dissolve 200 gm into 800 mL of distilled water.
6.1.7 MNNG (1—methyl—3--nitro—l—nitrosoguanidine),
Aldrich Chemical Co. (Milwaukee, Wisc.)
6.1.8 Silica gel #15, Ailtech 35/60 mesh (Deerfield,
Ill.). Activate at 180°C and store in a
dessicator.
6.1.9 Sulfuric acid — Use ACS grade concentrated acid.
6.1.10 Copper (II) sulfate pentahydrate — ACS reagent
grade.
6.1.11 Silanized glass wool (J&W Scientific, Inc.)
6.2 STANDARD MATERIALS
6.2.1 See Table 3 for source and physical information.
6.2.2 The reference internal standard
1,2—dibromopropane is 98% pure (Chem Services,
Westchester, Penn.).
6.2.3 The surrogate 2,3—dibromopropionic acid is 99%
pure (Aldrich Chemical Co., Milwaukee, Wisc.).
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6.3 REAGENT WATER — Organic—pure water (OPW) is made in the
laboratory by a Corning megapure all—glass distillation
system (model MP3A, Corning, N. Y.). The source water
for the MP3A is purified laboratory water (Super—Q),
which has gone through several stages of cartridge—type
purification to filter and demineralize the water and
trap the organic compounds.
6.4 HALOACETIC ACID STANDARD STOCK SOLUTIONS
6.4.1 Individual haloacetic acid stock solutions —
Prepare the 5 individual haloacetic acids and the
trich].orophenol stock solutions as follows:
Weigh on an analytical balance -0.15 gin of each
analyte. Dilute each standard in methanol to 10
mL in a screw—top volumetric flask. Transfer
each stock standard solution to a separate clean
14—mL amber vial and store in a freezer at —11°C.
The stock standards are used for six months.
6.4.2 Multicomponent haloacetic acid spiking solution.
6.4.2.1 Prepare a 6 component spiking solution
using the individual haloacetic acid
stock solutions (Section 6.4.1).
Dilute -16.7 ,uL of each stock standard
into a 10—mL volumetric flask
containing 9 mL of methanol, except use
—8.4 ul of the 2,4,6—trichlorophenol
solution. After all the stock
solutions have been added, dilute to
volume with methanol to achieve -25 ppm
of each analyte, except -12.5 ppm for
the 2,4,6—trichiorophenol. The spiking
solution is used for three months.
6.4.2.2 The microliter volumes are measured
with a gas—tight syringe (Hamilton
Corp.) using the solvent flush delivery
technique. The solvent flush can be
performed with a 25—pL syringe by first
drawing up 2.5 uL of solvent and then
drawing the syringe plunger to the 5 pL
mark with air. From the 5 pL mark
measure the amount of stock solution
desired and then deliver the entire
contents to the volumetric flask.
6.5 FIALOESTER STANDARD STOCK SOLUTIONS
6.5.1 individual haloester stock solutions — Prepare
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the 6 individual methyl ester stock solutions as
follows: weigh on an analytical balance -0.1 gm
of each commercially—available methyl ester (see
Table 1) in a l0—mL volumetric flask and dilute
each standard with methanol. Prepare the methyl
ester for dibromoacetic acid by derivatizing 1 mL
of a —20,000 ppm solution of the acid (Section
6.4.1) and 100 pL of methanol (follow
derivatization steps in Section 10.5.1 through
10.5.6), except substitute dibromoacetic acid
stock solution and methanol for tBME in step
10.5.3). After derivatizing, transfer the ester
quantitatively to a 2—mL volumetric flask with a
Teflon—lined screw—cap and dilute to the mark
with tSME. The stock standards are used for six
months.
6.5.2 Multicomponent ha].oester spiking solution —
Prepare a 6 component spiking solution by
diluting -10 pL of each haloester stock standard,
except use —5 pL of the 2,4,6—trichioroanisole
(methyl ester of the phenol), in a 10—mL
volumetric flask and bring to volume using
methanol. This will yield a mixture containing
appoximately 10 ppm of each analyte, except for
the 2,4,6—trichioroanisole which will be
approximately S ppm. The spiking solution is
used for three months.
6.5.3 Direct injection standards.
6.5.3.1 Prepare direct injection standards
using the 10 ppm multicomponent
haloester spiking solution, a 30 ppm
internal standard spiking solution, and
a 10 ppm methanol solution of methyl—
2,3—dibromopropionate (surrogate ester;
see Section 6.8.2). Prepare direct
injection standard by diluting the
appropriate volumes of the
multicomponent haloester spiking mix,
internal standard spiking solution, and
surrogate ester solution with enough
tEME to give a final volume of 1.0 mL.
6.5.3.2 For example, measure 970 pL of tBME
into a 1.8—mL vial and add 5.0 pL of
the multicomponent haloester spiking
solution, plus 10 pL of the internal
standard spiking solution and 10 pL of
the methyl—2,3—dibromopropionate
—8—
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spiking solution, to yield a 50 ppb
direct injection ha].oester standard (25
ppb of 2,4,6—trichloroanisole, 300 ppb
of internal standard, and 100 ppb
surrogate ester).
6.6 INTERNAL STANDARD STOCK SOLUTIONS
6.6.1 Internal standard stock solution — Prepare an
internal standard (IS) stock solution by weighing
approximately 50 mg of 1,2—dibromopropane into a
10—mL volumetric flask and bring to volume with
methanol. This will yield approximately a 5000
ppm stock solution. Stock standards are used for
six months.
6.6.2 Internal standard spiking solution — Make a 30
ppm IS spiking solution by delivering
approximately 60 4 uL of IS stock solution into a
l0—mL volumetric flask and dilute to volume with
methanol. Divide this solution evenly among six
1.8—niL vials and store at —11°C. The spiking
solution is used for three months.
6.6.3 Internal standard addition to extracts — Add 20
uL IS spiking solution to each 2 mL extract (see
Section 10.4.2), yielding IS at the 300 ppb
level.
6.7 SURROGATE STOCK SOLUTIONS
6.7.1 Surrogate stock solution — Make a 20,000 ppm
surrogate (SUR) stock solution by weighing
approximately 0.2 gm of 2,3—dibromopropionic acid
into a 10—niL screw—cap volumetric flask and
dilute to the mark with tBME. Stock solutions
are used for six months.
6.7.2 Surrogate spiking solution — Make a 10 ppm SUR
spiking solution by delivering approximately 5 uL
of SUR stock solution into a 10—niL volumetric
flask and dilute to volume with methanol. Divide
this solution evenly among six 1.8—mL vials and
store at —11°C. Spiking solutions are used for
three months.
6.7.3 Surrogate addition to sample aliquots — Add 20 1 uL
SUR spiking solution to each 20—niL alIquot of
sample (see Section 10.2.2), yielding SUR at the
10 ppb level (which will equal 100 ppb after
extraction and concentration to 2 mL).
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6.8 ESTERIFIED SURROGATE STOCK SOLUTIONS
6.8.1 Surrogate ester stock solution — Prepare a 10,000
ppm SUR ester stock solution by derivatizing 1 m l.
of the SUR stock solution and 100 1 uL of methanol
(follow derivatization steps in Section 10.5.1
through 10.5.6, except substitute SUR stock
solution and methanol for tBI1E in step 10.5.3).
After derivatizing, transfer the ester
quantitatively to a 2—mL volumetric flask with a
Teflon—lined screw—cap and dilute to the mark
with tENE. Stock solutions are used for six
months.
6.8.2 Surrogate ester spiking solution — Z’lake a 10 ppm
SUR ester spiking solution by delivering
approximately 10 pL of SUR ester stock solution
into a 10—mL volumetric flask and dilute to
volume with methanol. Spiking solutions are used
for three months.
6.8.3 Surrogate ester addition to direct standards —
Add 10 pL SUR ester spiking solution to each (1
mL of) direct injection standard (see Section
6.5.3), yielding SUR ester at the 100 ppb level.
SAMPLE COLLECTION, PRESERVATION, AND STORAGE
7.1 SAMPLE COLLECTION
7.1.1 Samples are collected in quadruplicate.
7.1.2 The sampling tap is allowed to flush for
approximately 5 minutes to allow the water
temperature to stabilize and the stagnant lines
to be flushed.
7.1.3 Samples are collected in nominal 40—mL vials with
Teflon—faced septa and screw caps. The sample
vials are filled such that no air bubbles pass
through the sample. The bottles are not rinsed
before filling and are not allowed to overfill,
since the bottles contain a preservative. The
sample vials are sealed headspace free.
7.2 SAMPLE PRESERVATION
7.2.1 Ammonium chloride (NH 4 C1) is used as the
preservative agent. The ammonium chloride acts
as a preservative by forming monochioramine in
the presence of free chlorine; monochioramine
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does not react with humic or fulvic acids to form
the haloacetic acids during established holding
times under refrigerated temperatures (4°C).
Likewise, monochloramjne does not react with
phenol to form 2,4,6—trichiorophenol during
established holding times under refrigerated
temperatures. -
7.2.2 Approximately 65 mg of crystalline NH 4 C1 is added
to each vial prior to sampling.
7.3 SAI’IPLE STORAGE
7.3.1 Samples are stored at 4°C and sample extracts are
stored at —11°C until analysis. Analyses should
be performed as soon as possible after
collection; however, the samples can be held for
9 days. Sample extracts can be held for 21 days.
8. CALIBRATION AND STANDARDIZATION
8.1 Aqueous calibration standards are prepared in OPW by
injecting a measured amount of the multicomponent
haloacetic acid solution directly into water using the
solvent flush technique.
8.2 Five different concentration levels from 0.5 to 30 pg/L
for the HAAs and 0.25 to 15 pg/L for 2,4,6—trichioro—
phenol are prepared in 40—mL Teflon—lined screw—top
bottles containing 20 mL of OPW. The same extraction/
esterification procedure is used for both the standards
and samples. The calibration standards are extracted
and analyzed along with the samples using the same batch
of diazomethane solution.
8.3 A five—point calibration plot is constructed using a
0.5, 5, 10, 20, and 30 pg/L extracted set of standards
(the trichlorophenol calibration standards are at half
of the BAA levels). A point—to—point calibration curve
passing through zero is generated from the plotted
points for each analyte using chromatography software
(XTRACHROME II, Nelson Analytical, Cupertino, Calif.).
The internal standard quantitation method is used to
determine unknown concentrations using the fitted
curves.
9. QUALITY CONTROL
9.1 MONITORING FOR INTERFERENCES
9.1.1 Laboratory reagent blanks — A laboratory reagent
blank is analyzed each day to check for any
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interferences.
9.1.2 Travel blanks for each sampling location are
prepared in the laboratory by filling 40—mL
vials, as described above (Section 7.1.3), with
OPW. These are shipped to the sampling locations
and back to the laboratory with the sample
bottles.
9.1.3 Each reagent bottle of tBME is analyzed on the GC
before it is used.
9.2 QUALITY ASSURANCE/QUALITY CONTROL PROTOCOL
The Quality Assurance/Quality Control (QA/QC) protocol
covers accuracy, precision, independent verification,
internal standard, and the use of a surrogate. Accuracy
is dependent on many factors, but the most important is
the calibration curve. Accuracy is monitored by
calculating the recoveries of samples which have been
enhanced with known concentrations of the compounds of
interest. Precision is another parameter that is
dependent on more than one factor. The precision of a
method is monitored by analyzing samples in duplicate
and calculating the normalized difference between the
two analyses. Independent verification of a method is
done by interlaboratory calibration. The internal
standard is used to insure that the GC makes consistent
injections of samples and standards. A surrogate
compound is added to samples and standards to insure
that the water is sufficiently acidified prior to
extraction and that the derivatization reaction was
successful.
All of the above mentioned parameters are important in
assuring that good quality data are produced. It is
important to note that all portions of a QA/QC program
must meet the established standards in order for an
analysis to be considered in control.
9.2.1 Method Detection Limits
Initial calculations of the method detection
limits (MDLS) are made according to the Code of
Federal Regulations 40 part 136, July 1, 1987. A
set of 7 standards are prepared in OPW at 1 to 5
times the estimated detection limit. Each
standard is analyzed according to the method and
the standard deviation of the 7 replicate
measurements for each analyte is determined. The
method detection limit is determined for each
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analyte as follows:
MDLI = t (S).
t — 3.143 (student t value for 6 degrees of
freedom and 99 percent confidence level).
S standard deviation of the 7 replicate
analyses.
These MDLs are used as minimum reporting levels
(MRLs), except where the instrumental detection
limit has proved to be higher. Often, the MRLs
correspond to the lowest level standard on the
calibration curve.
9.2.2 Calibration Curves
Quantitation is done using an external standard
calibration curve with internal standard
referencing (relative areas). Standards are
prepared in OPW water spiked with haloacetic
acids and trichiorophenol and extracted with the
same solvent and derivatized with •the same
diazomethane as that used for the samples. The
extracted standards are used to compensate for
the varying extraction efficiencies of the
different compounds in the analysis. A five—
point calibration curve encompassing 0.5 to 30
pg/LI range, except 2,4,6—trichiorophenol which is
from 0.25 to 15 pg/LI, is analyzed each day prior
to analysis of samples. Samples with levels
greater than the highest standard analyzed are
reanalyzed with dilution. When a sample is
reanalyzed, only the analytes that were at levels
higher than the calibration curve will have their
values obtained from the dilution; the other
analytes use the values obtained from analysis of
the original sample.
9.2.2.1 Acceptance/Rejection Criteria
The curve is determined acceptable if
the fit is smooth. Also, the new
calibration curve is compared to the
previous curve to insure that they are
comparable. The injection is
determined to be acceptable if the
internal standard is acceptable (see
Section 9.2.3). All internal standard
area counts (pv/seconds) should be
within +/— 10 percent for all standards
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in the calibration curve. A standard
extract with a surrogate area that is
outside +/— 15 percent of the average
standard surrogate area will not be
used to set up the calibration plots.
9.2.2.2 QC Corrective Action
The problem is determined and
corrected. The calibration curve is
reanalyzed on the GC. If reanalysis
does not produce a satisfactory curve,
then a new set of calibration standards
are prepared. The standards are
reanalyzed until an acceptable curve is
obtained. All sample extracts analyzed
with an out—of—control calibration
curve are reanalyzed. The corrective
action is documented in the HAA
notebook and signed by the immediate
supervisor and QC officer.
9.2.3 Internal Standard
The internal standard (1,2—dibromopropane) is
added to each extract. The purpose of the
internal standard is to monitor injections made
by the autosampler, it is used as a reference
peak for peak identification by establishing
relative retention times, and it is used in the
calculation of unknown samples. Also, the
internal standard corrects for any deviation in
sample volume injected.
9.2.3.1 Acceptance/Rejection Criteria
A sample injection is deemed acceptable
if the area counts (pv/seconds) of the
internal standard peak do not vary more
than +/— 10 percent from other samples
which are analyzed using the same batch
of diazomethane.
9.2.3.2 Corrective Action
The problem is determined and
corrected. The out—of—control sample
extracts are reanalyzed on the GC. If
reanalysis is not acceptable, then the
out—of—control samples are reextracted
and reanalyzed. If the reextracted
samples are not acceptable or the
samples have exceeded the holding time,
then the out—of—control samples are
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resampled and reanalyzed or the results
are recorded as suspect and out of
control. Such data will not be entered
into the database. The corrective
action is documented in the HAA
notebook and signed by the immediate
supervisor and QC officer.
9.2.4 surrogate
9.2.4.1 The surrogate (2,3—dibromopropionic
acid) is spiked directly into all water
samples prior to acidification and
extraction. If the surrogate area is
low or absent, there has been a
derivatization problem (e.g., water in
extract) or extraction problem (e.g.,
water insufficiently acidified).
9.2.4.2 Acceptance/Rejection Criteria
An extract is deemed acceptable if the
area counts of the surrogate peak do
not vary more than +/— 15 percent from
other samples that have been analyzed
using the same batch of diazomethane.
9.2.4.3 Corrective Action
The problem is determined and
corrected. The out—of—control sample
extracts are reanalyzed on the GC. If
reanalysis is not acceptable, then
those samples are reextracted and
reanalyzed. If the reextracted samples
are not acceptable or the samples have
exceeded the holding time, then the
out—of—control samples are resampled
and reanalyzed or the results are
recorded as suspect and out of control.
Such data will not be entered into the
database. The corrective action is
documented in the HAA notebook and
signed by the immediate supervisor and
QC officer.
9.2.4 Spikes
Sample spikes re analyzed to monitor the
extraction efficiency of specific analytes in
sample matrices. This measures the accuracy of
the method in a natural matrix. Randomly
selected spiked samples are analyzed at a
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frequency of at least 10 percent of the samples.
The spike solution is prepared in methanol.
Typically samples are spiked with 4 pL of
haloacetic acid spiking solution to achieve a
concentration of 5 pg/L for HAAs and 2.5 ug/L for
the 2,4,6—trichlorophenol. Higher spike levels
may be needed when sample levels are above 10
pg/L. Data are entered into the QC table
directly after the analysis. The QC charts are
reviewed by the analyst and the immediate
supervisor.
9.2.4.1 Acceptance/Rejection Criteria
All spike recoveries must fall within
the upper and lower control limits to
be acceptable. Initial control limits
are defined by calculating the mean
percent recovery from the most recent
20 sample spike data points. Control
limits for HAA5 are defined as +/— two
times the standard deviation. Warning
limits for HAAs are defined as +/— one
time the standard deviation. If a
sample recovery is above or below the
warning limits, this indicates there is
a potential problem. The problem is
determined and corrected before the
analysis is out of control. Control
limits and warning limits are
recalculated on a semiannual basis
using the most recent 50 spiked sample
percent recovery values. Data points
that are out of control are not
included in the recalculation of new
control limits. Control limits are
recalculated when any major changes are
made in the analytical procedure (i.e.
new type of column) and after at least
20 points have been collected.
9.2.4.2 QC Corrective Action
The problem is determined and
corrected. The sample extracts and
spiked sample extract are reanalyzed
from the point where the last sample
spike recovery was in control. If the
spike recovery is still not acceptable,
then the samples are reextracted from
the point where the last spike was in
control and a sample is respiked and
reanalyzed only for those analytes that
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are out of control. If the spike
recovery is not acceptable or samples
have exceeded the holding time, then
the samples are resampled and
reanalyzed from the point where the
last spike was in control. A sample is
respiked •and reanalyzed. if reanalysis
is not possible the results are
recorded as suspect for only those
•analytes that are out of control. Such
data will not be entered into the
database. The corrective action is
documented in the HAA notebook and
signed by the immediate supervisor and
QC officer.
9.2.5 Duplicates
Sample duplicates are analyzed in order to
monitor the precision of the method. Duplicates
are analyzed on randomly selected samples at a
frequency of at least 10 percent of the samples
Data are entered into the QC table within 24
hours after the analytical run is completed. The
QC charts are reviewed by the analysts and the
immediate supervisor.
9.2.5.1 Acceptance/Rejection Criteria
Control limits are determined by
calculating the range as a function of
the relative standard deviation
(coefficient of variation) as specified
in Standard Methods proposed method
1020B. The range (R) is calculated by
taking the absolute difference of the
duplicate values as follows:
R x 1 —x 2 I (x 1 and x 2 are the
duplicate values)
The normalized range (Re) is calculated
by dividing the range (R) by the
average of the duplicate values (xm):
R
R =
Xm
Xm = l ÷ 2
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A mean normalized range (Rm) is
calculated for 20 pairs of duplicate
data points initially and 50 pairs of
points semiannually:
ER
Rm
n
n number of duplicate pairs
The variance (s 2 ) of the normalized
ranges is calculated:
E(R— a) 2
The standard deviation (s) is
calculated as the square root of the
variance.
The upper and lower control limits are
defined as am + 3s and zero,
respectively. All duplicates must fall
within the control limits to be
acceptable. The upper warning limit is
defined as Rm + 2s. If an R is
outside the warning limit, tf is
indicates there is a potential problem.
The problem is investigated before the
analysis is out of control. Control
limits are recalculated on an annual
basis using the most recent 20 points.
ata points that are out of control are
not included in the recalculation of
new control limits. Control limits are
recalculated when any major changes are
made in the analytical procedure (i.e.
new type of column) and after at least
20 points have been collected.
9.2.5.2 QC Corrective Action
The problem is determined and
corrected. The sample extracts and the
duplicate extracts are reanalyzed from
the point where the last sample
duplicate was in control. If the
duplicate is still not acceptable, then
the samples are reextracted from the
point where the last duplicates were in
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control and a duplicate is reanalyzed
only for those analytes that were out
of control. If the duplicates are
still unacceptable or the sample
holding time has been exceeded, then
the samples are resampled and
reanalyzed from the point where the
last duplicates were in control. A
duplicate is reanalyzed. If this is
not possible the results for only those
analytes that were out of control are
recorded as suspect and out of control.
Such data will not be entered into the
database. The corrective action is
documented in the HAA notebook and
signed by the immediate supervisor and
QC officer.
9.2.6 Check Samples
Check samples are used to provide an independent
confirmation of the accuracy of the method.
Check samples are not available for haloacetic
acids at the present time; therefore an
interlaboratory calibration is used instead.
9.2.7 Interlaboratory Calibration
Samples will be split and sent to another
laboratory that is experienced in HAA analysis
when available. This will allow the comparison
of results with another laboratory. This will
provide a means of independent verification.
When split samples are sent a spiked sample will
also be sent to verify the quality assurance of
the other laboratory. Results will be recorded
in the HAA notebook.
10. PROCEDURE
10.1 SAI4PLE PREPARATION
10.1.1 Samples and standards are removed from storage
and allowed to reach room temperature.
10.2 NICROEXTRACTION
10.2.1 A 20—niL aliquot of sample water is withdrawn from
the sample container by a 20—mL glass syringe and
delivered to a 40—mL vial with Teflon—faced
septum and screw cap.
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10.2.2 Add 20 uL of surrogate spiking solution (10 ppm
2,3—dibromopropionic acid in methanol) to each
sample including standards and blanks. Any
addition of haloacetic acid spiking solution is
done at this stage.
10.2.3 Take one vial at a time and add the following in
sequence: 1 mL of concentrated sulfuric acid
from a 2—mL size Brinkman dispensette (to lower
pH to < 0.5), 5 niL of tBME from a 5—mL size
Brinkutan dispensette, 3 gut of copper sulfate (one
scoop using a custom made “3 gm” stainless steel
measure), and 6 gut of baked sodium sulfate (two
scoops). Immediately cap the vial and shake by
hand to break up any salt clumps and place in
vial holder.
10.2.4 Continue to the next sample vial repeating step
10.2.3 for each vial before proceeding to the
next sample.
10.2.5 After all the sample vials have been prepared,
place the vial holding block containing the
sample vials onto the mechanical shaker. Shake
the vials at fast speed for 7 minutes.
10.2.6 The vials are removed from the vial holder,
placed upright and allowed to stand for 3
minutes.
10.3 SEPARATION AND CONCENTRATION
10.3.1 Separate the ether layer using an empty glass
chromatography colunm (22 x 300 mm with Teflon
stopcock, not glass). Pour the entire contents
of one sample vial into a clean column. Drain
about half of the blue water layer back into the
extraction vial and pour through the column again
as a rinse. Drain the bottom water layer to
waste. The presence of the copper sulfate
enhances visualization of the phase separation of
the ether and salted water.
10.3.2 Prepare a conical funnel by using a small amount
of silanized glass wool to plug the bottom of the
funnel and then add two 3 gut scoops of acidified
baked sodium sulfate to the funnel. Drain the
ether layer from the column through the drying
funnel into a 10—niL graduated concentration tube.
10.3.3 Rinse the column 3 times with -l niL tBNE each
—20—
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time, draining through and washing the sodium
sulfate, with enough ether to give a final volume
of 8 mL.
10.3.4 Concentrate the dried extract to 0.8 mL using a
moderate stream of nitrogen blowing on the
extract while in a water bath set at 40°C. Apply
the nitrogen to the sample before heating the
sample in a water bath. (The blowdown takes
—15—20 mm.)
10.4 DERIVATIZATION
10.4.1 Quantitatively transfer the extract (avoiding
aeration) using a disposable pasteur pipette to a
2—mL volumetric flask with a Teflon—faced—septum
screw top. Do at least a 0.5— and 0.2—mL rinse;
final volume must be less than 1.7 mL.
10.4.2 Add 20 pL of 30 ppm 1,2—dibromopropane (the
internal standard) in methanol. Place extracts
in a —11°C explosion—safe freezer for 3 mm to
cool extracts before adding diazomethane.
10.4.3 Add 250 pL of cold diazomethane/tBr4E solution
(see Section 10.5 for preparation of
diazomethane), using a pasteur—pipette—tipped
Eppendorf pipetter, to each volumetric flask.
Cap immediately with a Teflon—lined screw cap;
mix gently by inverting once. Then go on to next
sample.
10.4.4 Allow the samples to esterify for 15 minutes at
4°C in an explosion—safe or —proof refrigerator.
10.4.5 Add approximately 0.01 gm of silica gel to each
autosampler (1.8—mL) vial to quench any excess
diazomethane.
10.4.6 After the 15 minutes, allow extracts to stand
another 15 minutes until they reach room
temperature, then dilute to the mark with tBNE.
Transfer each extract evenly between two
autosampler vials prepared above (Section
10.4.5). Each extract should be in contact with
diazomethane for approximately the same of amount
of time before quenching.
10.5 PREPARATION OF DIAZONETHANE
10.5.1 Add -133 mg of NNNG to the inside tube of the
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diazomethane generator.
10.5.2 Add 0.5 mL of OPW to the MNNG and tighten the cap
and septum.
10.5.3 Add 2 mL of tBME to the outside tube of the
generator.
10.5.4 Place the butyl—o—ring in the glass joint and
clamp with the pinch clamp.
10.5.5 Place the generator and its contents in an ice
bath. Bath must contain enough ice to keep
dia omethane at 0°C until used.
10.5.6 Add 600 pL of 5.0 N NaOH with a 1—mL syringe.
The syringe needle is placed through the septum
on the top of the generator tube (check that the
syringe needle is on the opposite side of the
vapor exit hole). Add the NaOH at a rate of 1
drop per 5 seconds.
10.5.7 Allow the derivatization process to continue for
30 mm after addition of all the NaOH and use
immediately. Provide enough ice to keep the
solution at 0°C while standing.
10.5.8 If more diazomethane is needed, prepare two or
more batches and combine just before use.
10.6 ANALYSIS
10.6.1 At the beginning of each analytical run, two tBME
solvent blanks are injected to condition the GC
and to verify that no interferences are present.
10.6.2 The data are collected on a Hewlett Packard model
300 microcomputer (Palo Alto, Calif.) with Nelson
Analytical xtrachrome chromatography software
(Cupertino, Calif.) Autosampler information
(rack# & vial*) is communicated to the data
system for sample identification purposes. The
data files are designated KAXXXXY and KBXXXXY
where I(A and KB are the codes designating the HAA
analysis on the analytical and confirmation
columns, XXXX is the month and day in numbers and
Y is a unique sequential cycle number assigned to
each data file by the data system. The data
files are archived to magnetic tape.
10.6.3 See Table 1 for retention times.
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TABLE 1A
METHOD DETECTION LIMITS (MDLs)
AND MINIMUM REPORTING LEVELS (MRL5)
MDLs MRLs
Compounds ( pg/L) ( pg/L )
Monochioroacetic acic (MCAA) 0.6 1.0
Monobromoacetic acid (MBAA) 0.4 0.5
Dichioroacetic acid (DCAA) 0.6 0.6
Trichioroacetic acid (TCAA) 0.6 0.6
Dibromoacetic acid (DBAA) 0.6 0.6
2,4,6—Trichiorophenol (TCP) 0.4 0.4
TABLE lB
RETENTION TIMES (RTs)
RTS (mm)
DB—1701 DB—5
Compoundsa Column Column
Methyl chioroacetate (MeCA) 8.68 5.01
Methyl bromoacetate (MeBA) 14.50 8.00
Methyl dichioroacetate (MeDCA) 15.96 8.73
Methyl trichioroacetate (MeTCA) 22.79 16.37
Methyl dibromoacetate (MeDBA) 27.48 24.72
2,4,6—Trichioroanisole (TCAn) 33.52 32.88
1,2—Dibromopropane (IS)b 12.40 9.33
Methyl—2,3—dibromopropioflate (SUR ester)C 29.58 27.94
aThese compounds are the methyl ester derivatives of the
haloacetic acids, trichiorophenol, and surrogate.
blnternal Standard
Csurrogate ester
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TABLE 2
GAS-CHROMATOGRApHIC CONDITIONS
Analytical Column
Type: Fused silica capillary
(Durabond—1701, J&W Scientific, Folsom, Calif.)
Length: 30 meters
Internal diameter: 0.25 millimeters
Film thickness: 0.25 micron
Confirmation Column
Type: Fused silica capillary
(Durabond—5, J&W Scientific, Folsom, Calif.
Length: 30 meters
Internal diameter: 0.25 millimeters
Film thickness: 0.25 micron
Temperature program:
37°C >136°C > 236°C
21 mm 11°C/mm 3 mm 20°C/mm 3 mm
Injector
Injection volume: 2 pL
Temperature: 157°C
Splitless injection: Split valve opened at 0.47 mm
Split Flow: 77 mL/min
Detectors
Type: Electron capture
Temperature: 297°C
Gases
Carrier: Helium (99.999 percent purity)
Flow: 1.0 mL/min at 37°C
Makeup: Nitrogen (99.999 percent purity)
Flow: 23 mL/min
Autosampler Parameters — (for Varian model 8035 autosampler)
Purge pulse pressure 33 psi
number of purge
pulses 2
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TABLE 3
ANALYTI CAL STANDARDS
Molec— Boiling
Purity ular Point
Compound Source percent) Weight ( °C @ mm)a
MCAA Aldrichb 99 94.5 61
MBKP Aldrich 99+ 138.95 87
DCAA Aldrich 99+ 128.94 119
TCAA Aldrich 98 163.39 15].
DBAA PfaltzC 99 217.86 125—130
TCP Chem svcd 95 197.45 246
IS Aldrich 95 201.9 140—142
SUR Aldrich 99 231.88 160 @ 20
MeCA Aldrich 99+ 108.52 130 @ 740
MeSA Aldrich 98 152.98 5]. @ 15
MeDCA Aldrich 99+ 142.97 143
MeTCA Aldrich 99 177.42 152—153
MeDBA MwDSCe
TCAn Aldrich 99 211.48 132 @ 28
SUR ester MWDSCe
aDegrees centigrade at reduced pressure in millimeters of
mercury.
bAidrich Chemical Company, Inc., Milwaukee, Wisc.
Cpfaltz & Bauer, Inc., Waterbury, Conn.
dchem Service, Inc., Westchester, Pa.
eDerivatize acid at Metropolitan Water District laboratory.
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ANALYSIS OF CHLORAL HYDRATE:
MICRO METHYL t-BUTYL ETHER EXTRACTION
1. SCOPE AND APPLICATION
1.1 This method was developed to analyze for chioral hydrate
in drinking water.
1.2 The experimentally determined method detection limit was
calculated (Table 1). The method has been shown to be
useful for chloral hydrate over a range of 0.05 to 30
micrograms per liter (pg/L).
2. SUMMARY OF METHOD
2.1 Twenty milliliters (mL) of sample is extracted with 4 mL
of methyl t—butyl ether (MTBE) with a salting agent to
increase the extraction efficiency. The analysis is
conducted on a gas chromatograph (GC) with temperature
programming and a fused silica capillary column to
obtain baseline resolution of chloral hydrate from other
disinfection by—products (see Table 1). Detection is
performed with an electron capture detector (ECD).
Aqueous calibration standards are extracted and analyzed
in the same manner as the samples in order to compensate
for extraction efficiency.
3. INTERFERENCES
3.1 The highest grade methyl t—butyl ether is used to
minimize the contribution of interference from the
extraction solvent.
3.2 Glassware, except volumetric flasks, is cleaned as
follows:
3.2.1 Detergent washed.
3.2.2 Rinsed twice with tap water.
3.2.3 Rinsed twice with deionized water.
3.2.4 Rinsed twice with Millipore Super-Q System
(Bedford, Mass.) water.
3.2.5 Baked in oven at 180°C for one hour; however,
septa are baked at 80°C for one hour.
3.3 Cleaning procedure for volumetric flasks.
—1—
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3.3.1 Immediately after use rinse three times with
methanol.
3.3.2 Allow volumetric flasks to air dry in the
ventilation hood for 3 hours.
3.3.3 These flasks are only reused for the preparation
of chloral hydrate standards.
4. SAFETY
4.1 Chioral hydrate is a controlled substance determined to
be poisonous and corrosive; each chemical is treated as
a potential health hazard and handled under a
ventilation hood.
4.2 All Occupational Safety and Health Association (OSHA)
regulations regarding safe handling of chemicals and
laboratory procedures are used in this method.
5. APPARATUS, EQUIPMENT AND MATERIALS
5.1 SAMPLE CONTAINERS — samples are collected in 40—mL
screw—cap vials with Teflon/silicone septa closures.
5.2 EXTRACTION VIALS — Extraction vials are 30 mL (nominal
25 mL) with open—top screw cap and Teflon/silicone septa
closure.
5.3 MICROLITER SYRINGES — 10, 25, 50, 500 and 1000
microliter (pL) sizes from Hamiliton Co., Reno, Nev.,
and a 20—mL syringe from Becton—Dickson Co., Rutherford,
N. 3.
5.4 VOLUMETRIC FLASKS — glass stoppered, 2 and 5 mL.
5.5 MECHANICAL SHAKER — For the ether extraction process, a
mechanical shaker table is used with the 30—mL vials.
The vials are inserted into a custom—made wooden holding
block (32—vial capacity). The shaker was purchased from
the Eberbach Corp., Ann Arbor, Mich.
5.6 EXTRACT AND STANDARD SOLUTION STORAGE CONTAINERS -
1.5—niL clear and amber glass, 15—mL and 1—ounce (oz)
amber—glass screw—cap vials with Teflon—lined septa.
5.7 GAS CHROMATOGRAPH — A Varian model 3500 GC (Sunnyvale,
Calif.), equipped with split/splitless injector, ECD,
and model 8035 autosampler, is used for the analysis.
See Table 2 for analytical conditions.
—2—
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5.7.1 The analytical column is a fused silica DB—1 (J&W
Scientific, Inc., Folsom, Calif.) with a 1.0
micron (p) film, internal diameter (ID) of 0.25
millimeters (mm) and 30 meters (m) in length.
5.7.2 A constant current pulse modulated Nickel 63 ECD
with capillary size cell is used for detection.
5.7.3 The carrier and make—up gases are high purity
(99.999 percent) grade which pass through
Drierite, molecular seive 5A, activated charcoal,
and finally an oxygen purifying cartridge before
entering the GC. Two—stage metal diaphragm high
purity regulators are used at the compressed gas
sources. Digital flow controllers regulate
carrier gas flow and all gas lines are 1/8 inch
copper tubing which have been acetone—rinsed and
baked before use.
6. REAGENTS AND CONSUMABLE MATERIALS
6.1 REAGENTS
6.1.1 Extraction solvent is EM Science “OmniSolv” t—
butyl methyl ether (Cherry Hill, N. J.).
6.1.2 Sodium sulfate is granular (12—60 mesh), “Baker
Analyzed” reagent (Jackson, Tenn.), baked at 400°C
overnight in a stainless steel pan and stored in a
glass desiccator with Drierite.
6.1.3 Acetone for stock standard solutions is Baker
Resi—Analyzed (Phillipsburg, N. 3.).
6.1.4 The dechlorination agent is L—(+)—ascorbic acid,
powder, “Baker Analyzed” biochemical grade
(Phillipsburg, N. J.).
6.2 STANDARD MATERIALS
6.2.1 A 1000 mg/L chioral hydrate (99.3 percent purity)
solution is obtained from the USEPA, Repository
for Toxic and Hazardous Materials, Cincinnati,
Ohio.
6.2.2 The reference internal standard 1,2—dibromopropane
is 98 percent pure (Chem Services, Inc.,
Westchester, Penn.). The internal standard is
added at the 30 pg/L level in the ether used for
extraction.
—3—
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6.3 REAGENT WATER — Organic—pure water (OPW) is made in the
laboratory by a Corning megapure all—glass distillation
system (model MP3A, Corning, N. Y.). The source water
for the MP3A is purified laboratory water (Super—Q),
which has gone through several stages of cartridge—type
purification to filter and demineralize the water and
trap the organic compounds.
6.4 STANDARD STOCK SOLUTION
6.4.1 A 500 mg/L Stock I of chioral hydrate is prepared
in a 2—mL volumetric flask containing <1 mL
acetone. A 1000—pL volume of a 1000 mg/L (USEPA)
solution is delivered by a l000—pL gas tight
syringe. A solvent flush technique is used for
delivering the volume by first drawing up 0.5 pL
of acetone and then 1.0 pL of air before measuring
the volume of chioral hydrate solution. The
solution is then brought up to final volume with
acetone, stoppered and mixed by inverting the
flask several times. The solution is then split
evenly between two 1.5—mL amber—glass screw—cap
vials (with Teflon—faced septa), using a
disposable pasteur pipette, and stored at 4°C.
This stock solution is prepared fresh once a
month.
6.4.2 A secondary stock standard of 25 mg/L (Stock II)
is prepared in a 5—mL volumetric flask by diluting
250 uL of Stock I into 5 mL of acetone. The
solvent flush technique with a gas—tight syringe
is used. This solution is prepared each time a
new set of talibration standards are prepared.
6.4.3 A tertiary stock standard of 2 mg/L (Stock III) is
prepared in a 5—mL volumetric flask by diluting 20
uL of Stock I into 5 mL of acetone. The solvent
flush technique with a gas—tight syringe is used.
This solution is prepared each time a new set of
calibration standards are prepared.
6.4.4 A spike solution of 15 mg/L is prepared in a 5—mL
volumetric flask by diluting 150 yL of Stock I
into 5 mL of acetone. Typically, 4 p1 of spike
solution is added to a 20—mL sample, yielding a
spike concentration of 3 pg/L. This will provide
a spike sample concentration that is similar to
that which is found in many unspiked samples.
Since samples should be spiked at concentrtations
approximately 60 to 150 percent of concentrations
present in the unspiked sample, higher spike
levels are needed when sample levels are above 6
—4—
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ug/L. The spike solution is prepared every 2
weeks.
7. SAMPLE COLLECTION, PRESERVATION, AND STORAGE
7.1 SAMPLE COLLECTION
7.1.1 Collect all samples in triplicate.
7.1.2 The sampling tap is allowed to flush for
approximately 5 minutes to allow the water
temperature to stabilize and the stagnant lines to
be flushed.
7.1.3 Samples are collected in nominal 40—niL vials with
Teflon—faced septa and screw caps. The sample
vials are filled such that no air bubbles pass
through the sample. The bottles are not rinsed
before filling and are not allowed to overfill,
since the bottles contain a preservative. The
sample vials are sealed headspace free.
7.2 SAMPLE PRESERVATION
7.2.1 Ascorbic acid is used as the dechlorination agent.
The ascorbic acid acts as a preservative by
reducing the free chlorine or chioramines.
7.2.2 Approximately 20 mg of powdered ascorbic acid is
added to each vial prior to sampling.
7.3 SAMPLE STORAGE
7.3.1 Samples and sample extracts are stored at 4°C
until analysis. Analyses should be performed as
soon as possible after collection. Chloral
hydrate is stable for 21 days.
8. CALIBRATION AND STANDARDIZATION
8.1 Aqueous calibration standards are prepared in OPW by
injecting the correct amount of stock standard solution
directly into water using the solvent flush technique.
8.2 Standards are prepared at the time samples are
extracted. Six different concentration levels (from
0.05 to 30 1 ug/L) are prepared in 30 mL vials with
Teflon—faced septa and screw caps, containing 20 mL of
OPW. Each vial is spiked with the appropriate volume of
the appropriate stock solution (see Table 3). The
aqueous calibration standards are extracted in the same
—5—
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manner as the samples (see Section 10.2.2—10.2.5).
8.3 A set of standards in the range of 0.05 to 30 ,ug/L (see
Table 3) is analyzed by GC before the samples are
analyzed. An external standard method is used to
determine the concentration of the samples. The
internal standard is not used in the quantitation but is
used as a reference peak for peak identification and as
an indicator of injection errors (see Section 9.2.3). A
plot ? area versus concentration (in pg/L) is prepared
by using a point—to point fit passing through zero.
Calculations are made from only the linear portions of
the curve. If the sample run extends over 2 days of GC
injections, then another set of standards are injected
at the end of the run. Solvent blanks are run after the
standards.
9. QUALITY CONTROL
9.1 MONITORING FOR INTERFERENCES
9.1.1 Laboratory reagent blanks — A laboratory reagent
blank is analyzed each day to verify any
interferences.
9.1.2 Travel blanks for each sampling location are
prepared in the laboratory by filling 40—mL vials,
as described above (see Section 7.2.2), with OPW.
These are shipped to the sampling site and back to
the laboratory with the sample bottles.
9.1.3 Each reagent bottle of MTBE is analyzed before it
is used.
9.2 QUALITY ASSURANCE/QUALITY CONTROL PROTOCOL
The Quality Assurance/Quality Control (QA/QC) protocol
covers accuracy, precision, independent verification and
the use of an internal standard. Accuracy is dependent
on many factors, but the most important is the
calibration curve. Accuracy is monitored by calculating
the recoveries of samples which have been enhanced with
known concentrations of the compounds of interest.
Precision is another parameter that is dependent on more
than one factor. The precision of a method is monitored
by analyzing samples in duplicate and calculating the
normalized difference between the two analyses.
Independent verification of a method is done by
analyzing QC check samples and interlaboratory
calibration. The internal standard is used to insure
that the GC makes consistent injections of samples and
—6—
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standards.
All of the above mentioned parameters are important in
assuring that good quality data are produced. It is
important to note that all portions of a QA/QC program
must meet the established standards in order for an
analysis to be considered in control.
9.2.1 Method Detection Limits
Initial calculations of the method detection
limits (MDLs) are made according to the Code of
Federal Regulations 40 part 136, July 1, 1987. A
set of 7 standards are prepared in OPW at 1 to 5
times the estimated detection limit. Each
standard is analyzed according to the method and
the standard deviation of the 7 replicate
measurements for each analyte is determined. The
MDL is determined for chioral hydrate as follows:
MDL = t (S)
t = 3.143 (student t value for 6 degrees of
freedom and 99 percent confidence level)
S — standard deviation of the 7 replicate analyses
These MDL5 are used as minimum reporting levels
(MRL5), except where the instrumental detection
limit has proved to be higher. Often, the MRLs
correspond to the lowest level standard on the
calibration curve.
9.2.2 Calibration Curves
QuantitatiOn is done using an external standard
calibration curve. Standards are prepared in OPW
spiked with chioral hydrate and extracted with the
same solvent as that used for the samples (see
Section 8). The extracted standards are used to
compensate for the extraction efficiency of
chloral hydrate in this analysis. A six—point
calibration curve encompassing the 0.05 to 30 pg/L
range for chioral hydrate is used, and the six
standards are analyzed each day prior to the
analysis of the samples.
9.2.2.1 Acceptance/Rejection Criteria
The curve is determined acceptable if the
fit is smooth. Also, the new calibration
curve is compared to the previous curve
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to insure that they are comparable. The
injection is determined to be acceptable
.f the internal standard is acceptable
(see Section 9.2.3). All internal
standard area counts (pV/seconds) should
be within +/— 10 percent for all
standards in the calibration curve.
9.2.2.2 QC Corrective Action
The problem is determined and corrected.
The calibration curve is re—analyzed on
the GC. If re—analysis does not produce
a satisfactory curve, then a new set of
calibration standards are prepared. The
standards are re—analyzed until an
acceptable curve is obtained. All sample
extracts are re—analyzed from the last
point where calibration curves were in
control. The corrective action is
documented in the chioral hydrate
notebook and signed by the immediate
supervisor and QC officer.
9.2.3 Internal Standard
The internal standard (1,2—dibromopropane) is
spiked directly into each new bottle of solvent at
a concentration of 30 pg/L. The solvent is then
used to extract both samples and calibration
standards. The purpose of the internal standard
is to monitor injections made by the autosampler.
9.2.3.1 Acceptance/Rejection Criteria
A sample injection is deemed acceptable
if the area counts (pV/seconds) of the
internal standard peak do not vary more
than +7— 10 percent from other samples
which are extracted using the same bottle
of solvent on the same date. The
internal standard areas of samples can
not be compared to those of calibration
standards when the samples and standards
are prepared using extraction solvent
from different bottles or on different
days. The internal standard area can
vary from bottle to bottle and day to
day.
9.2.3.2 Corrective Action
The problem is determined and corrected.
The sample extracts are re—analyzed. If
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reanalysis is not acceptable, then the
samples are re—extracted and re—analyzed.
If the re—extracted samples are not
acceptable or the samples have exceeded
the holding time, then the samples are
re—sampled and re—analyzed or the results
are recorded as suspect and out of
control. Such data will not be entered
into the database. The corrective action
is documented in the chloral hydrate
notebook and signed by the immediate
supervisor and QC officer.
9.2.4 Spikes
Sample spikes are analyzed to monitor the
extraction efficiency of chioral hydrate in sample
matrices. This measures the accuracy of the
method in a natural matrix. The spiked samples
are analyzed at a frequency of at least 10 percent
of the samples. Typically, the samples are spiked
with 4 pL of spike solution to achieve a
concentration of 3 pg/L for chloral hydrate, which
is the level that is typically found in samples.
Since samples should be spiked at concentrtations
app.roximately 60 to 150 percent of concentrations
present in the unspiked sample, higher spike
levels are needed when sample levels are above 6
pg/L. The spike volume must not exceed 5 4 uL per
20 mL of sample because of possible solvent
interference problems (the spike solution is
prepared in acetone). Thus, a different
concentration of spike solution may need to be
prepared. Data are entered into the QC table
directly after the analysis. The QC charts are
reviewed by the analyst and the immediate
supervisor.
9.2.4.1 Acceptance/Rejection Criteria
All spike recoveries must fall within the
upper and lower control limits to be
acceptable. Initial control limits are
defined by calculating the mean percent
recovery from the most recent 50 sample
spike data points. The 99 percent
confidence interval is +/— three times
the standard deviation, warning limits
are defined as +/— two times the standard
deviation. If a sample recovery is above
or below the warning limit this indicates
there is a potential problem. The
—9—
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problem is determined and corrected
before the analysis is out of control.
Control limits and warning limits are re-
calculated on a semiannual basis using
the most recent 50 spiked sample percent
recovery values. Data points that are
out of control are not included in the
re—calculation of new control limits.
Control limits are re—calculated when any
major changes are made in the analytical
procedure (i.e. new type of column) and
after at least 20 points have been
collected.
9.2.4.2 QC Corrective Action
The problem is determined and corrected.
The sample extracts and spiked sample
extract are re—analyzed from the point
where the last sample spike recovery was
in control. If the spike recovery is
still not acceptable, then the samples
are re—extracted from the point where the
last spike was in control and a sample is
re—spiked and re—analyzed. If the spike
recovery is not acceptable or samples
have exceeded the holding time, then the
samples are re—sampled and re—analyzed
from the point where the last spike was
in control. A sample is re—spiked and
re—analyzed. If re—analysis is not
possible the results are recorded as
suspect and out of control. Such data
will not be entered into the database.
The corrective action is documented in
the chlora]. hydrate notebook and signed
by the immediate supervisor and QC
officer.
9.2.5 Duplicates
Sample duplicates are analyzed in order to monitor
the precision of the method. Duplicates are
analyzed on randomly selected samples at a
frequency of at least 10 percent of the samples.
Data are entered into the QC table within 24 hours
after the analytical run is completed. The QC
charts are reviewed by the analyst and the
immediate supervisor.
9.2.5.1 Acceptance/Rejection Criteria
Control limits are determined by
—l 0-
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calculating the range as a function of
the relative standard deviation
(coefficient of variation) as specified
in Standard Methods proposed method
1020B. The range (R) is calculated by
taking the absolute difference of the
duplicate values as follows:
R Ixi—x 2 1 (x 1 and x 2 are the duplicate
values Y
The normalized range (Re) is calculated
by dividing the range (R) by the average
of the duplicate values (xm):
Rn = R
Xm
xl + x 2
2
A mean normalized range (Rm) is
calculated for 50 pairs of duplicate data
points:
ER
Rm ____
n
n number of duplicate pairs
The variance (s 2 ) of the normalized
ranges is calculated:
E(Rn - Rm) 2
S =
n—i
The standard deviation (s) is calculated
as the square root of the variance.
The upper and lower control limits are
defined as R + 3s and zero,
respectively. All duplicates must fall
within the control limits to be
acceptable. The upper warning limit is
defined as R + 2s. If an R is outside
the warning limit, this indicates there
is a potential problem. The problem is
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investigated before the analysis is out
of control. Control limits are
recalculated on a semiannual basis using
the most recent 50 points. Data points
that are out of control are not included
in the recalculation of new control
limits. Control limits are recalculated
when any major changes are made in the
analytical procedure (i.e. new type of
column) and after at least 20 points have
been collected.
9.2.5.2 QC Corrective Action
The problem is determined and corrected.
The sample extracts and the duplicate
extracts are re—analyzed from the point
where the last sample duplicate was in
control. If the duplicate is still not
acceptable, then the samples are re—
extracted from the point where the last
duplicates were in control and a
duplicate is re—analyzed. If the
duplicates are still unacceptable or the
sample holding time has been exceeded,
then the samples are re—sampled and re-
analyzed from the point where the last
duplicates were in control. A duplicate
is re—analyzed. If this is not possible
the results are recorded as suspect and
out of control. Such data will not be
entered into the database. The
•corrective action is documented in the
chioral hydrate notebook and signed by
the immediate supervisor and QC officer.
9.2.6 Check Samples
The check samples are used to provide an
independent confirmation of the accuracy of the
method. Check samples are not available for
chloral hydrate at the present time.
9.2.7 Interlaboratory Calibration
Samples will be split and sent to another
laboratory that is experienced in ch].oral hydrate
analysis when available. This will allow the
comparison of results with another laboratory.
This will provide a means of independent
verification. When split samples are sent a
chiora]. hydrate spiked sample will also be sent to
verify the quality assurance of the other
—12--
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laboratory. Results will be recorded in the
chioral hydrate notebook.
10. PROCEDURE
10.1 SAMPLE PREPARATION
10.1.1 Samples and standards are removed from storage
and allowed to reach room temperature.
10.2 MICROEXTRACTION AND ANALYSIS
10.2.1 A 20—mL aliquot of sample water is withdrawn
from the sample container by a 20—mL glass
syringe and delivered to a 30—mL vial with
Teflon—faced septum and screw cap.
10.2.2 A 4—mL volume of MTBE (containing the internal
standard) is added to the vial by a Brinkman
Dispensette and the vial is capped.
10.2.3 After all the vials are filled, 5 gm of sodium
sulfate is measured, using a custom—made “5 gm”
stainless—steel scoop, and poured into each
vial. The vial is capped immediately, shaken by
hand for several seconds to break up the clumps
of sodium sulfate.
10.2.4 After all the vials have been sealed and
prepared for extraction, they are placed in a
vial holder and shaken for 5 minutes in a
mechanical shaker.
10.2.5 The vials are removed from the vial holder,
placed upright and allowed to stand for 5
minutes. Equal volumes of extract are
transferred into two 1.5—mL clear—glass vials by
a pasteur pipet.
10.2.6 At the beginning of each analytical run, a MTBE
solvent blank is injected to condition the GC
and to verify that no interferences are present.
10.2.7 The data are collected on a Hewlett Packard
model 300 microcomputer (Palo Alto, Calif.) with
Nelson Analytical Xtrachrome chromatography
software (Cupertino, Calif.). Autosampler
information (rack* & vial#) is communicated to
the data system for sample identification
purposes. The data files are designated XOXXXXY
where XO is a code designating the chioral
—13—
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hydrate analysis, XXXX is the month and day in
numbers and Y is a unique sequential cycle
number assigned to each data file by the data
system. The data files are archived to magnetic
tape.
10.2.8 See Table 1 for retention times.
—14—
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TABLE 1
METHOD DETECTION LIMITS (MDLs),
MINIMUM REPORTING LEVELS (MRLs),
AND RETENTION TIMES (RTs)
MDLs MRLs RTs
Compounds ( pg/L) ( pg/L) ( mm )
Chloroform 757*
Bromodichioromethane 11.91*
Chioral Hydrate 0.03 0.05 12.78
Dibroinochioromethane 21.38*
Bromoform 27.66*
1, 2_Dibromopropanea 26.35
*Retention times for trihalomethanes presented for
information purposes.
ainternal standard.
-------
TABLE 2
GAS—CHROMATOGRAPHI C CONDITIONS
Column
Type: Fused silica capillary
(Durabond—1, J&W Scientific, Fo].som, Calif.)
Length: 30 meters
Internal diameter: 0.25 millimeters
Film thickness: 1.0 micron
Temperature program:
35°C > 41°C > 81°C > 181°C
10 mm 1°C/mm 6 mm 5°C/mm 0 mm 25°C/mm 1 mm
Injector
Injection volume: 2 pL
Temperature: 177°C
Split].ess injection: Split valve opened at 0.5 nUn
Detector
Type: Electron capture
Temperature: 272°C
Gases
Carrier: Helium (99.999 percent purity)
Flow: 1.5 mL/min at 25°C
Makeup: Nitrogen (99.999 percent purity)
Flow: 24 mL/min
Autosampler Parameters — (for Varian model 8035 autosampler)
Purge pulse pressure 30 psi
Number of purge
pulses 2
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TABLE 3
CONCENTRATION OF CHLOR.AL HYDRATE IN CALIBRATION STANDARDS
Stock 111* Stock II
Level: 1 2 3 4 5 6
Stock vol—
umea (pL)• 0 • 5 b 2 5 b 10 C 24 d
Chloral Hydrate
Level ( 1 ug/L) 0.05 0.25 1.0 5.0 15 30
*2 mg/L stock solution.
#25 mg/L stock solution.
avolume of stock spiked into 20 mL of OPW.
blo_pL, syringe used.
C25_pL syringe used.
dso_PL syringe used.
-------
ANALYSIS OF CYANOGEN CHLORIDE:
PURGE—AND-TRAP METHOD
1. SCOPE AND APPLICATION
1.1 This method was developed to analyze for low parts—per—
billion (ppb) levels of cyanogen chloride (CNC1) in
drinking water. The method is also used to monitor the
formation of cyanogen chloride in drinking water
treatment pilot plant studies.
1.2 The method detection limit (MDL) has been determined to
be 0.02 microgram per liter ( 4 ug/L); the minimum
reporting level (MRL) has been set at 0.1 pg/L. The
method has been shown to perform well for the analysis
of cyanogen chloride over a concentration range of 0.1
to 10 pg/L in a drinking water matrix.
2. SUMMARY OF METHOD
2.1 This method is a modification of the United States
Environmental Protection Agency (USEPA) Method 524.2.
This method describes a purge—and—trap technique using a
gas chromatograph/mass spectrometer (GC/MS). Cyanogen
chloride is extracted from 25 milliliters (mL) of a
water sample by bubbling (purging) with helium gas. The
CNC1 is trapped onto a Tenax trap. When the purging
process is completed, the Tenax trap is heated and
backflushed with helium to remove (desorb) the trapped
CNC1. The CNC1 is cryofocussed onto an uncoated
capillary pre—column prior to being flash heated onto a
narrow bore capillary column. The column is temperature
programmed to separate CNC1 from other chemical
components. Cyanogen chloride is then detected with a
mass spectrometer that is interfaced with the gas
chromatrograph. Aqueous calibration standards are
purged and trapped and analyzed in the same manner as
the samples in order to compensate for purging
efficiency.
3. INTERFERENCES
3.1 The purge—and—trap method often transfers significant
amounts of water and air into the analytical system.
The transfer of water and air results in interferences
to early eluting compounds. Since cyanogen chloride
elutes extremely early chromatographically, caution must
be taken to ensure minimization of water and air
transfer into the analytical system.
—1—
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3.2 Glassware is cleaned as follows:
3.2.1 Detergent washed.
3.2.2 Rinsed twice with tap water.
3.2.3 Rinsed twice with deionized water.
3.2.4 Rinsed twice with Millipore Super—Q System
(Bedford, Mass.) water.
3.2.5 Baked in oven at 180°C for one hour; however,
septa are baked at 80°C for one hour, while
volumetric glassware are rinsed twice with
reagent—grade acetone and air—dried.
4. SAFETY
4.2. Cyanogen chloride in its pure form is a highly toxic gas
that needs special attention and care whenever it is
being handled in order to prevent unsafe incidents from
occurring. Only trained personnel that are familiar
with the health effects, hazards and safe handling of
cyanogen chloride are allowed to work directly with this
gas. Always work in well ventilated fume hoods whenever
working with cyanogen chloride. Read the attached
Material Safety Data Sheet (MSDS) for cyanogen chloride
for detailed information and procedures for handling
this chemical.
4.2 An internal laboratory protocol should be established.
All Occupational Safety and Health Association (OSHA)
regulations and laboratory procedures for the safe
handling of chemicals are used in this method.
5. APPARATUS, EQUIPMENT AND MATERIALS
5.1 SAMPLE CONTAINERS — samples are collected in 40—mL
screw—cap vials with Teflon/silicone septa closures.
5.2 MICROLITER SYRINGES — 5, 10, 25, 50, and 1000 microliter
(pL) sizes from Hamiliton Co., Reno, Nevada, and a 25 mL
syringe from Tekmar Co., Cincinnati, Ohio.
5.3 VOLUMETRIC FLASKS — glass stoppered, 10, 50, and 100 niL.
5.4 STANDARD SOLUTION STORAGE CONTAINERS - 2-niL and 15-niL
amber glass screw—cap vials with Teflon—lined septa.
5.5 GC/MS — The GC/MS is a Finnigan 4021 (San Jose, Calif.)
equipped with Tekmar LSC—2 purge—and—trap apparatus and
Tekmar 1000 capillary cryofocussing interface module.
—2—
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5.5.1 The analytical column is a fused silica DB—S (J&W
Scientific, Inc., Folsom, Calif.) with a 1.0
micron (p) film, internal diameter (ID) of 0.25
millimeters (nun) and 30 meters (in) in length.
5.5.2 The precolumn is an uncoated, deactivated, fused
silica niegabore column (0.53 mm ID), approximately
0.5 m in length (J&W Scientific, Inc.).
5.5.3 The trap is Tekmar trap #1 containing Tenax only.
5.5.4 The carrier gas is an ultrahigh purity (99.999
percent) grade which passes through Drierite,
molecular seive 5A, activated charcoal, and
finally an oxygen purifying cartridge before
entering the GC. A two—stage metal diaphragm high
purity regulator is used at the compressed gas
source. Pressure controllers regulate carrier gas
flow and all gas lines are 1/8 inch copper tubing
which have been acetone—rinsed and baked before
use.
6. REAGENTS AND CONSUMABLE MATERIALS
6.1 REAGENTS
6.1.1 Methanol for stock standard solutions is Purge &
Trap High Purity Grade by Baxter (Burdick &
Jackson, Muskegon, Mich.).
6.1.2 Dechiorinating agent is L—(+)—ascorbiC acid,
powder, “Baker Analyzed” biochemical grade
(Phillipsburg, N. J .).
6.2 STANDARD MATERIALS
6.2.1 The pure cyanogen chloride gas is available at
Solkatronic Chemical Inc., 30 Two Ridge Road,
Fairfield, N. J. 07006, (201) 882—7900.
6.2.2 A 1% cyanogen chloride standard (the balance is
nitrogen) is available at Scott Specialty Gases,
2600 Cajon Blvd., San Bernadino, Calif. 92411,
(714) 887—2571. At this time, the concentration
of the cyanogen chloride is not certified;
however, evaluation of one cylinder indicated that
one was quantitative.
6.2.3 The internal standard fluorobenzene is 99+% (Chem
Service, Westchester, Penn.)
—3—
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6.3 REAGENT WATER — Organic—pure water (OPW) is made in the
laboratory by a Corning megapure all—glass distillation
system (model NP3A, Corning, New York). The source
water for the MP3A is purified laboratory water (Super—
Q), which has gone through several stages of cartridge—
type purification to filter and demineralize the water
and trap the organic compounds.
6.4 STANDARD STOCK SOLUTIONS
6.4.1 Preparation of cyanogen chloride stock standard
from 1% cyanogen chloride gas in nitrogen:
6.4.1.1 The stock solution is prepared by
transferring a known volume (V) of gas
volumetically with a gas—tight syringe
through a septum into 10 mL of methanol
in a closed, screw—cap, 40—ml vial.
After all gas is transferred, the
bottle is shaken and stored in freezer
overnight before using. This process
will help keep the gas absorbed in the
solvent.
6.4.1.2 The volume of a known concentration of
cyanogen chloride gas to be transferred
into a known volume of solvent can be
determine by using the following
equation:
V = (C x v)/(l0 x d x m)
where,
V Volume of cyanogen chloride gas
mixture to be transferred into the
solvent in units of mL.
C = Concentration of cyanogen chloride
stock solution to be prepared in units
of pg/mL (or ppm).
v = Volume of solvent to be used in
units of mL.
m = % cyanogen chloride in gas mixture.
d = Density of cyanogen chloride (CNC1)
gas, where:
—4—
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d = molecular weight CNC] . x Istd x !actual
molar volume Tactual std
d = 61.48 273 P (mm Hg )
22.41 273+T(° C) 760
where P — atmospheric pressure and
T = room temperature at laboratory.
(This corrects for variations in one’s
laboratory from standard temperature,
pressure conditions.)
6.4.1.3 Therefore, to make a 100 4 cig/mL stock
solution, at 1 atmosphere (pressure 760
mm Hg) and 22°C room temperature,
transfer 39.39 mL of 1% cyanogen
chloride gas mixture to 10 mL methanol.
6.4.1.4 This 100 pg/mL stock solution is good
(stable) for approximately three
months.
6.4.2 Preparation of cyanogen chloride stock standard
from pure gas:
NOTE: Follow proper safety precautions; cyanogen
chloride is extremely toxic.
6.4.2.1 In a fume hood the cyanogen chloride
gas cylinder is fitted with a pressure
regulator, on/off valve, and
approximately 1 m length of megabore
fused silica precolumn. In order to
remove any air that may be present, the
line is minimally flushed by turning on
the gas cylinder valve while the pre—
column is submerged in a beaker of
methanol. The valve is shut and the
methanol solution is disposed of in a
safe manner. Care should be taken not
to bleed the line into the open air as
some cyanogen chloride may be released
into the fume hood.
6.4.2.2 Eight milliliters of methanol are
placed in a 10—mi volumetric flask.
The alcohol—wetted glass surfaces are
allowed to air dry and the flask is
stoppered and weighed. The flask is
unstoppered, the megabore column is
submerged into the methanol, and the
cyanogen chloride gas is bubbled into
—5—
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the methanol for 0.5 to 1 minute. Then
the flask is stoppered and reweighed.
If necessary, the bubbling is repeated
until at least 50 mg of cyanogen
chloride have been added. The volume
is adjusted beyond 10 mL, if necessary,
with the addition of an appropriate
amount of methanol using a syringe to
yield a final concentration of cyanogen
chloride of 5.0 mg/mL (5000 ppm).
6.4.2.3 The stock solution is transferred to a
14—mL Teflon—lined screw—cap vial and
stored in an explosion—safe freezer.
This solution is good (stable) for
approximately three months.
6.4.3 Preparation of internal standard stock solution:
6.4.3.1 Nine milliliters of methanol are placed
in a 10—mL volumetric flask. The
alcohol—wetted glass surfaces are
allowed to air dry and the flask is
stoppered and weighed to the nearest
0.1 mg. Fluorobenzene is added
dropwise into the methanol without
contacting the neck of the flask until
at least 50 mg have been added. The
flask is stoppered and reweighed. The
stock stolution is adjusted to the
appropriate volume to yield a
concentration of 5.0 mg/mL. The flask
is stoppered and inverted three times
to mix.
6.4.3.2 The solution is transferred to a 14—mL
Teflon—lined screw—cap vial and stored
in an explosion—safe freezer. This
solution is good (stable) for
approximately six months.
6.5 SPIKING SOLUTIONS
6.5.1 A working spiking solution of 5 ,ig /mL cyanogen
chloride is prepared daily by diluting 50 pL of
the 100 pg/mL stock standard (Section 6.4.1) with
950 uL methanol in a 2—niL gas—tight vial.
6.5.2 Alternatively, a working spiking solution of 5
pg/niL cyanogen chloride is prepared daily by
diluting the 5.0 mg/mL stock standard (Section
6.4.2):
—6—
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6.5.2.1 Dilute 10 pL of the 5.0 mg/mL stock
standard with 990 uL of methanol in a
2—mL gas—tight vial to yield a
concentration of 50 pg/mL. This
secondary dilution standard is prepared
daily and can also be used as the
working spiking solution for the
preparation of high—level calibration
standards (to minimize the volume of
methanol delivered to the sample).
6.5.2.2 Dilute 100 pL of the 50 pg/niL secondary
dilution standard solution with 900 pL
of methanol in a 2—mL gas—tight vial to
yield a concentration of 5 pg/inL. This
working spiking solution is prepared
daily.
6.5.3 Preparation of internal standard spiking solution:
6.5.3.1 Dilute 10 pL of the 5.0 mg/mL stock
standard (Section 6.4.3) with 990 pL of
methanol in a 2—mL gas—tight vial to
yield a concentration of 50 pg/mL.
This secondary dilution standard
solution is stable for approximately
one week.
6.5.3.2 Dilute 100 pL of the 50 ,ug/mL secondary
dilution standard solution with 900 pL
of methanol in a 2—mL gas—tight vial to
yield a concentration of S pg/niL. This
working spiking solution is stable for
approximately two days.
6.5.3.3 The addition of 5 pL of the working
spiking solution to a 25—niL sample will
yield an internal standard
concentration of 1.0 pg/L.
7. SAMPLE COLLECTION, PRESERVATION, AND STORAGE
7.1 SAMPLE COLLECTION
7.1.1 Samples are collected in quadruplicate.
7.1.2 The sampling tap is allowed to flush for
approximately 5 minutes to allow the water
temperature to stabilize and the stagnant lines to
be flushed.
—7—
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7.1.3 Samples are collected in nominal 40—zak vials with
Teflon—faced septa and screw caps. The sample
vials are filled such that no air bubbles pass
through the sample. The bottles are not rinsed
before filling and are not allowed to overfill,
since the bottles contain a dechlorination agent.
The sample vials are sealed headspace free.
7.2 SAMPLE PRESERVATION
7.2.1 Approximately 20 mg of ascorbic acid is added to
each 40—zak sample bottle prior to sample
collection. The acorbic acid is used as a
dechlorination agent.
7.3 SAMPLE STORAGE
7.3.1 Store the samples at 4°C until-time of analysis.
Analyses should be performed as soon as possible
after collection and receipt at the laboratory, as
cyanogen chloride slowly degrades in an ascorbic—
acid—preserved sample.
8.0 CALIBRATION AND STANDARDIZATION
8.1 Quantitation is performed using an external calibration
curve, with the peak area of cyanogen chloride m/z of 61
relative to the internal standard m/z of 96 peak.
Calibration standards are prepared in 02W spiked with
cyanogen chloride. Standards are purged, trapped, and
analyzed with the same methodology as that used for the
samples.
8.2 Initial 6—point standard calibration: An initial
6—point standard calibration is established by analyzing
6 cyanogen chloride standards at varying concentrations
ranging between 0.1 1 ug/L and 10 pg/L. The response
factors are calculated with the use of an internal
standard. For a small working range, fewer calibration
standards are analyzed, as long as the shape of the
curve is adequately characterized.
8.3 Daily on—going standard calibration: At the beginning
of each day of analysis, a daily cyanogen chloride
standard at 5 pg/k is analyzed and its response factor
calculated. Typically, 2—3 runs of the standard are
made to ensure that the instrument is stable. If the
response factor has changed significantly, a new
calibration curve is generated (see Section 9.2.3).
—8—
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9. QUALITY CONTROL
9.1 MONITORING FOR INTERFERENCES
9.1.1 Laboratory Reagent Blanks — A laboratory reagent
blank is analyzed each day to verify any
interferences.
9.1.2 Travel blanks for each sampling location are
prepared in the laboratory by filling 40—mL vials,
as described above, with OPW. These are shipped
to the sampling site and back to the laboratory
with the sample bottles.
9.2 QUALITY ASSURANCE/QUALITY CONTROL PROTOCOL
The Quality Assurance/Quality Control (QA/QC) protocol
covers accuracy, precision, independent verification and
the use of an internal standard. Accuracy is dependent
on many factors, but the most important is the
calibration curve. Accuracy is monitored by calculating
the recoveries of samples which have been enhanced with
known concentrations of the compounds of interest.
Precision is another parameter that is dependent on more
than one factor. The precision of a method is monitored
by analyzing samples in duplicate and calculating the
relative difference between the two analyses.
Independent verification of a method is done by
interlaboratory calibration. The internal standard is
used to quantitatively compensate for variations in the
GC/MS response.
All of the above mentioned parameters are important in
assuring that good quality data are produced. It is
important to note that all portions of a QA/QC program
must meet the established standards in order for an
analysis to be considered in control.
9.2.1 Method Detection Limits
Initial calculations of the method detection limit
(MDL) are made according to the Code of Federal
Regulations 40 part 136, July 1, 1987. A set of 7
standards are prepared in OPW at 1 to S times the
estimated detection limit. Each standard is
analyzed according to the method and the standard
deviation of the 7 replicate measurements for
cyanogen chloride is determined. The MDL is
determined for each analyte as follows:
—9—
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MDL = t (S)
t 3.143 (student t value for 6 degrees of
freedom and 99 percent confidence level)
S — standard deviation of the 7 replicate analyses
This MDL is used as the minimum reporting level
(MRL), except where the instrumental detection
limit has proved to be higher. Often, the MRL
corresponds to the lowest level standard on the
calibration curve.
9.2.2 Initial Calibration Curve
Quantitation is done using an external standard
calibration curve, with peak areas relative to an
internal standard. Standards are prepared in OPW
at 6 different concentration levels that encompass
a range between 0.1 and 10 pg/L. For a smaller
working range, fewer calibration standards are
analyzed, as long as the shape of the curve is
adequately characterized. The CNC1 standard
calibration curve is established prior to the
analysis of samples.
9.2.2.1 Acceptance/Rejection Criteria
The acceptance criteria requires that the
response factors for each point on the
calibration must agree to within 10
percent relative standard deviation
(RSD). RSD less than or equal to 10
percent will define the concentration
range analyzed to be linear and,
therefore, the average response factor
can be used for quantitation. RSD
greater than 10 percent indicates non-
linearity and, therefore, quantitation
must be based upon a best quadratic fit
for the multi—point standard calibration
curve. The curve is determined to be
acceptable if the fit is smooth. Also,
the response factors are compared to the
previous calibration curve to ensure that
they are comparable.
• 9.2.2.2 QC Corrective Action
The problem is determined and corrected.
If re—analysis does not produce a
satisfactory curve, then a new set of
calibration standards are prepared or the
—10—
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mass spectrometer is retuned. The
standards are re—analyzed until an
acceptable curve is obtained. If the
curve is plateauing above one of the
calibration standard levels, the working
range will be limited by the highest
level standard that characterizes a
smooth, unplateaued section of the curve.
No samples are analyzed until the
calibration curve is in control. The
corrective action is documented on the
CNC1 daily worksheet and signed by the
immediate supervisor and QC officer.
9.2.3 Daily On—Going Standard Calibration
9.2.3.1 Acceptance/Rejection Criteria
If the true value of cyanogen chloride
for the daily standard agrees with the
calculated value from the initial multi—
point standard calibration curve to
within 10 percent difference, then real
samples can begin to be analyzed.
9.2.3.2 QC Corrective Action
If the true value is greater than 10
percent different from the calculated
value, then a new multi—point standard
calibration must be established before
analyzing real samples. Note, if the
first daily standard analyzed has a much
different response factor than the
subsequent ones, it is rejected as
reflecting that the instrument was not
stabilized yet for that day. The
corrective action is documented on the
CNC1 daily worksheet and signed by the
immediate supervisor and QC officer.
9.2.4 internal Standard
The internal standard (fluorobenzene) is spiked
directly into the 25—mL sample syringe prior to
purging a sample. The purpose of the internal
standard is to quantitatively compensate for
variability in the GC/MS response.
9.2.4.1 Acceptance/Rejection Criteria
A GC/MS analysis is deemed acceptable if
the area counts of the internal standard
peak do not vary more than +/— 20 percent
—11—
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from other samples which are analyzed
that same day.
9.2.4.2 Corrective Action
The problem is determined and corrected.
The samples that fail the internal
standard acceptance criteria are re-
analyzed. If re—analysis is not
acceptable, then these samples are re-
analyzed again. If all the sample
aliquots are used up, then the samples
with out—of—control internal standard
areas are re—sampled and re—analyzed or
the results are recorded as suspect and
out of control. Such data will not be
entered into the database. The
corrective action is documented on the
cyanogen chloride daily worksheet and
signed by the supervisor and the QC
officer.
9.2.5 Spikes
Sample spikes are analyzed to monitor the purging
efficiency of cyanogen chloride in sample
matrices. This measures the accuracy of the
method in a natural matrix. The spiked samples
are analyzed at a frequency of at least 10 percent
of the samples. The samples are spiked at
concentrations approximately 60 to 150 percent of
concentrations present in the unspiked sample.
Data are entered into the QC table directly after
the analysis. The QC charts are reviewed by the
analyst and the immediate supervisor.
9.2.5.1 Acceptance/Rejection Criteria
All spike recoveries must fall within the
upper and lower control limits to be
acceptable. Initial control limits are
defined by calculating the mean percent
recovery from the most recent 50 sample
spike data points. The 99 percent
confidence interval is +/— three times
the standard deviation. Warning limits
are defined as ÷/— two times the standard
deviation. If a sample recovery is above
or below the warning limit this indicates
there is a potential problem. The
problem is determined and corrected
before the analysis is out of control.
Control limits and warning limits are re—
—12—
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calculated on a semiannual basis using
the most recent 50 spiked sample percent
recovery values. Data points that are
out of control are not included in the
re—calculation of new control limits.
Control limits are re—calculated when any
major changes are made in the analytical
procedure (i.e. new type of column) and
after at least 20 points have been
collected.
9.2.5.2 QC Corrective Action
The problem is determined and corrected.
Another sample is spiked and analyzed.
If the spike recovery is still not
acceptable, then the purge—and—trap
system and GC/MS must be trouble—shot
until the problem is determined and
corrected. If the spike recovery is not
acceptable or samples have exceeded the
holding time, then the samples are re -
sampled and re—analyzed from the point
where the last spike was in control. A
sample is re—spiked and re—analyzed. If
re—analysis is not possible the results
are recorded as suspect and out of
control. Such data will not be entered
into the database. The corrective action
is documented on the cyanogen chloride
daily worksheet and signed by the
immediate supervisor and QC officer.
9.2.6 Duplicates
Sample duplicates are analyzed in order to monitor
the precision of the method. Duplicates are
analyzed on randomly selected samples at a
frequency of at least 10 percent of the samples.
If a set of samples is expected to not contain
cyanogen chloride, then duplicate spike analyses
are performed. Data are entered into the QC table
within 24 hours after the analytical run is
completed. Duplicate spike data are entered into
the duplicate QC table and as two separate entries
in the spike QC table. The QC charts are reviewed
by the analysts and the immediate supervisor.
9.2.6.1 Acceptance/Rejection Criteria
Control limits are determined by
calculating the range as a function of
the relative standard deviation
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(coefficient of variation) as specified
in Standard Methods proposed method
1020B. The range (R) is calculated by
taking the absolute difference of the
duplicate values as follows:
R = jxi—x 2 1 (x 1 and x 2 are the duplicate
values)
The normalized range (Re) is calculated
by dividing the range (R) by the average
of the duplicate values (xm):
R
Xm
X 1 + X 2
Xm 2
A mean normalized range (Rm) Is
calculated for 50 pairs of duplicate data
points:
Rm =
n
n number of duplicate pairs
The variance ( 2) of the normalized
ranges is calculated:
E(R — Rm) 2
S =
n—i
The standard deviation (s) is calculated
as the square root of the variance.
The upper and lower control limits are
defined as m + 3s and zero,
respectively. All duplicates must fall
within the control limits to be
acceptable. If duplicate spikes are
analyzed, both spikes must fall within
the spike control limits to be
acceptable. The upper warning limit for
duplicates is defined as Rm + 2s. If an
Rn is outside the warning limit, this
—14—
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indicates there is a potential problem.
The problem is investigated before the
analysis is out of control. Control
limits are recalculated on a semiannual
basis using the most recent 50 points.
Data points that are out of control are
not included in the recalculation of new
control limits. Control limits are
recalculated when any major changes are
made in the analytical procedure (i.e.
new type of column) and after at least 20
points have been collected.
9.2.6.2 QC Corrective Action
The problem is determined and corrected.
Another sample is analyzed in duplicate.
If the duplicate is still not acceptable,
then the purge—and—trap system and GC/NS
must be trouble—shot until the problem is
determined and corrected. If the
duplicates are still unacceptable or the
sample holding time has been exceeded,
then the samples are re—sampled and re-
analyzed from the point where the last
duplicates were in control. A duplicate
is re—analyzed. If this is not possible
the results are out of control and
recorded as suspect. Such data will not
be entered into the database. The
corrective action is documented on the
cyanogen chloride daily worksheet and
signed by the immediate supervisor and QC
officer.
9.2.7 Check Samples
Check samples are currently not available.
9.2.7.1 Acceptance/Rejection Criteria
These criteria cannot be established at
this time.
9.2.7.2 QC Corrective Action
This section does not apply at this time.
9.2.8 Interlaboratory Calibration
Samples will be split and sent to another
laboratory that is experienced in cyanogen
chloride analysis when available. This will
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allow the comparison of results with another
laboratory. This will provide a means of
independent verification. When split samples
are sent a cyanogen chloride spiked sample will
also be sent to verify the quality assurance of
both laboratories. Results will be recorded in
the cyanogen chloride notebook.
10. PROCEDURE
10.1 INSTRUMENT PREPARATION
10.1.1 At the beginning of each day of analysis, a
system blank is analyzed to verify that no
interferences are present and also to evaluate
instrumental conditions.
10.2 PURGE-AND-TRAP ANALYSIS
10.2.1 25 mL of the sample is placed in a 25—mL gas—
tight syringe. 1 4 ug/L of flurobenzene internal
standard is added through the tip of the sample
syringe. The sample is placed in the glass
sparger of the Tekmar LSC—2 unit and purged for
6 minutes.
10.2.2 When the purge cycle has completed, the cooling
cycle of the Tekmar 1000 cryofocussing unit is
started. The parameters on the Tekmar 1000 unit
are set at —150°C and 4—second heating time.
The liquid nitrogen tank must be set at 50 psi
pressure to operate proper cooling of the cryo—
interface cross connector. A 1/4 inch copper
tubing is used at the liquid nitrogen exit end
of the cross connector. This is to help provide
for faster cooling of the cross connector.
10.2.3 When the cross connector has reached the proper
temperature, the sample is desorbed onto the
cryo—interface for 1½ minutes. The Tenax trap
is then baked for 5 minutes.
10.2.4 Acqusition is started when the heat cycle on the
Tekmar 1000 is completed.
10.2.5 See Table 1 for GC/MS operating conditions.
11. IDENTIFICATION
Identification is made by comparison of cyanogen chloride and
fluorobenzene spectrum in the samples with those in the
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standard. The ion abundances for ions given in Table 1 must
agree within 10% absolute with the daily standard. For
example, if an ion has a relative abundance of 30 percent in
the standard spectrum, its abundance in the sample spectrum
should be in the range of 20 to 40 percent.
—17—
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TABLE 1
GC Column
GAS CHROMATOGRAPH/MASS SPECTROMETER
OPERATING CONDITIONS
Type:
Length:
Internal diameter:
Film thickness:
Pre—column:
DB—5 fused silica
30 meters
0.25 millimeters
1.0 micron
1 m x 0.32 mm ID
capillary
fused silica
Temperature program:
10°C > 184°C
2 mm 20°C/mm
Injector
Temperature:
18 5°C
Gases
Carrier:
Flow:
Mass Spectrometer
Helium (99.999 percent purity)
2 mL/mia
Interface temperature:
Manifold temperature:
Ionizer temperature
setting:
Electron energy:
Acquisition:
185°C.
100°C.
27 0°C.
70 eV
700 scans at 0.6 sec/scan:
mt *
GC/MS Values
Low Mass (m/z )
34. 510
40. 512
44. 513
High Mass (m/z )
39. 512
43. 513
300. 590
Ti me
0.008
0.005
0.419
Cyanogen chloride:
Retention time:
Mass spectrum:
Fluorobenzene:
Retention time:
Mass spectrum:
1.5 mm
m/z 6]. (100%), m/z 63 (22%)
5.6 mm
m/z 96 (100%), m/z 70 (19%), m/z 50 (9%)
1
2
3
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ANALYSIS OF FORMALDEHYDE/ACETALDEHYDE:
MICRO PENTANE EXTRACTION
1. SCOPE AND APPLICATION
1.1 This method was developed to simultaneously analyze for
formaldehyde and acetaldehyde in drinking water.
1.2 The experimentally determined method detection limits
were calculated (Table 1). The method has been shown to
be useful for formaldehyde and acetaldehyde over a range
of 1 to 40 micrograms per liter (pg/L).
2. SUNMARY OF METHOD
2.1 Twenty milliliters (mL) of sample is derivatized with 1
mL of O—(2,3 ,4,5,6—pentafluorobenzyl)hydroxylainine
(PFBOAT and allowed to sit for 2 hours. The sample is
then quenched with concentrated sulfuric acid (H 2 SO 4 )
and extracted with 4 mL of pentane. The analysis is
conducted on a gas chromatograph (GC) with temperature
programming and a fused silica capillary column to
obtain baseline resolution of all the analytes.
Detection is with an electron capture detector (ECD).
Aqueous calibration standards are derivatized, extracted
and analyzed in the same manner as the samples in order
to compensate for extraction efficiency.
3. INTERFERENCES
3.1 Glassware, except volumetric flasks, is cleaned as
follows:
3.1.1 Detergent washed.
3.1.2 Rinsed twice with tap water.
3.1.3 Rinsed twice with deionized water.
3.1.4 Rinsed twice with Millipore Super—Q System
(Bedford, Mass.) water.
3.1.5 Baked in oven at 180°C for one hour; however,
septa are baked at 80°C for one hour.
3.2 Cleaning procedure for volumetric flasks.
3.2.1 immediately after use rinse several times with
methanol.
3.2.2 Allow volumetric flasks to air dry in the
-------
ventilation hood for 3 hours.
3.2.3 These flasks are only reused for the preparation
of aldehyde standards.
3.3 Polypropylene caps from 1—Chem Research, Inc. (Hayward,
Calif.) are used instead of the Bakerlite caps that
normally come with the vials. Bakerlite caps are made
from phenol and formaldehyde and are a potential
contaminant.
3.4 Formaldehyde and acetaldehyde are air pollutants, and
data have indicated that their concentrations are
increased when oxygenated fuels are used in automobiles.
In addition, formaldehyde in the air can be traced to
the presence of certain insulation materials.
Therefore, a laboratory reagent blank is analyzed each
day to determine if the laboratory air is contaminated.
Also, travel blanks are used to identify contamination
during sampling and shipping of the samples.
Unfortunately, though, travel blanks can become
contaminated during the shipment and storage of ice
chests prior to sampling (typically a two—week period),
so the interpretation of aldehyde data is more
problematic.
4. SAFETY
4.1 The toxicity of formaldehyde and acetaldehyde has not
been precisely defined; each chemical is treated as a
potential health hazard and handled under a ventilation
hood.
4.2 All Occupational Safety and Health Association (OSHA)
regulations regarding safe handling of chemicals and
laboratory procedures are used in this method.
5. APPARATUS, EQUIPMENT AND MATERIALS
5.1 SAMPLE CONTAINERS — samples are collected in 40—mL
screw—cap (polypropylene, 1—Chem Research, Inc.) vials
with Teflon/silicone septa closures.
5.2 EXTRACTION VIALS — Extraction vials are 30 mL (nominal
25 mL) with open—top screw cap (polypropylene, 1—Chem
Research, Inc.) and Teflon/silicone septa closure.
5.3 MICROLITER SYRINGES — 5, 10, 25, 50, 100 and 500
microliter (,uL) sizes from Hamiliton Co., Reno, Nev.,
and a 20—mL syringe from Becton—Dickson Co., Rutherford,
N. 3.
—2—
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5.4 VOLUMETRIC FLASK — glass stoppered, 10 mL.
5.5 MECHANICAL SHAKER — For the pentane extraction process,
a mechanical shaker table is used with the 30—mL vials.
The vials are inserted into a custom—made wooden holding
block (28—vial capacity). The shaker was purchased from
the Eberbach Corp., Ann Arbor, Mich.
5.6 EXTRACT AND STANDARD SOLUTION STORAGE CONTAINERS -
1.5—mL clear glass, 15—niL and 1—ounce (oz) amber—glass
screw cap vials with Teflon—lined septa.
5.7 GAS CHROMATOGRAPH — A Varian model 3500 GC (Sunnyvale,
Calif.), equipped with split/splitless injector, ECD,
and model 8035 autosampler, is used for the analysis.
See Table 2 for analytical conditions.
5.7.1 The analytical column is a fused silica DB—5 (J&W
Scientific, Inc., Folsom, Calif.) with a 1.0
micron (p) film, internal diameter (ID) of 0.25
millimeters (mm) and 30 meters (m) in length.
5.7.2 A constant current pulse modulated Nickel 63 ECD
with capillary size cell is used for detection.
5.7.3 The carrier and make—up gases are high purity
(99.999 percent) grade which pass through
Drierite, molecular sieve SA, activated charcoal,
and finally an oxygen purifying cartridge before
entering the GC. Two—stage metal diaphragm high
purity regulators are used at the compressed gas
sources. Digital flow controllers regulate
carrier gas flow and all gas lines are 1/8 inch
copper tubing which have been acetone—rinsed and
baked before use.
6. REAGENTS AND CONSUMABLE MATERIALS
6.1 REAGENTS
6.1.1 Extraction solvent is Burdick & Jackson (Muskegon,
Mich.) THM analysis grade pentane.
6.1.2 O_(2,3,4,5,6_PentafluorObeflZyl)hYdroxYlamifle
1 ydrochloride (PFBOA) is from Aldrich Chemical Co.
(Milwaukee, Wisc.).
6.1.3 Sulfuric acid is Fisher Scientific (Pittsburg,
Penn.) A.C.S. reagent grade.
6.1.4 The “dechiorinating agent” is ammonium chloride,
—3—
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granular, “Baker Analyzed” reagent (Phillipsburg,
6.1.5 The preservative is mercuric chloride, “Baker
Analyzed” reagent.
6.2 STANDARD MATERIALS
6.2.1 See Table 3 for source and physical information.
6.2.2 The reference internal standard 1,3—dibromopropane
is 98 percent pure (Chem Services, Inc.,
Westchester, Penn.). The internal standard is
added at the 180 pg/L level in the pentane used
for extraction.
6.3 REAGENT WATER — Organic—pure water (OPW) is made in the
laboratory by a Corning megapure all—glass distillation
system (model MP3A, Corning, N. Y.). The source water
for the MP3A is purified laboratory water (Super—Q),
which has gone through several stages of cartridge—type
purification to filter and demineralize the water and
trap the organic compounds. The OPW should be prepared
when needed, as storage can increase the opportunity for
contamination.
6.4 STANDARD STOCK SOLUTION
6.4.1 Stocks are prepared gravimetrically in OPW from
pure standards. Separate stock solutions are
prepared for formaldehyde and acetaldehyde. The
syringe and the volumetric flask used for
acetaldehyde should be placed in the freezer for
about 10 minutes before preparing this standard
due to the volatility of the compound. The pure
standard is weighed into a tared, 1O—mL volumetric
flask, so that the final concentration is between
2 to 6 mg/mL. Since formaldehyde is commercially—
available as a 37 weight percent solution in
water, the concentration must take into account
this dilution factor. The stock solutions are
diluted to final volume with OPW, stoppered and
mixed by inverting the flasks several times. The
stock solutions are transferred into clean, l—oz
amber—glass storage bottles with Teflon—faced
septa and screw caps, and they are stored at 4°C.
The formaldehyde stock is prepared fresh every 3
months. The acetaldehyde stock is prepared fresh
every month.
6.4.2 A spike solution is prepared by diluting the
—4—
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appropriate amount of each stock solution into 10
mL of OPW so that the resulting concentration of
each aldehyde is approximately 20 xng/L. The
solvent flush technique with a gas—tight syringe
is used. The spike solution is prepared every two
weeks.
7. SAMPLE COLLECTION, PRESERVATION, AND STORAGE
7.1 SAMPLE COLLECTION
7.1.1 Collect all samples in triplicate.
7.1.2 The sampling tap is allowed to flush for
approximately 5 minutes to allow the water
temperature to stabilize and the stagnant lines to
be flushed.
7.1.3 Samples are collected in nominal 40—mL vials with
Teflon—faced septa and screw caps (polypropylene,
1—Chem Research, Inc.). The sample vials are
filled such that no air bubbles pass through the
sample. The bottles are not rinsed before filling
and are not allowed to overfill, since the bottles
contain a preservative. The sample vials are
sealed headspace free.
7.2 SAMPLE PRESERVATION
7.2.1 Ammonium chloride (NH 4 C1) and mercuric chloride
(HgCl ) are used as the preservative agents. The
ammonium chloride acts as a preservative by
forming monochioramine in the presence of free
chlorine; monochioramine does not react with
natural organic material in the samples to form
these aldehydes during established holding times
under refrigerated temperatures (4°C). The
mercuric chloride prevents the bacterial
degradation of the aldehydes.
7.2.2 Approximately 65 mg of crystalline NH 4 C1 is added
to each vial prior to sampling.
7.2.3 Approximately 40 pL of 10 mg/mL HgC1 2 is added to
each vial prior to sampling. The concentration of
HgCl 2 in the sample will be approximately 10 mg/L.
7.3 SAMPLE STORAGE
7.3.1 Samples and sample extracts are stored at 4°C
until analysis. Analyses should be performed as
—5—
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soon as possible after collection due to the
instability of the formaldehyde. Typically, these
samples are derivatized and extracted upon receipt
at the laboratory.
8. CALIBRATION AND STANDARDIZATION
8.1 Aqueous calibration standards are prepared in OPW by
injecting the appropriate amount of spike solution
directly into water using the solvent flush technique.
8.2 Eight different concentration levels (from 0.5 to 40
pg/L) are prepared in 30—mL screw—cap (polypropylene, I —
Chem Research, Inc.) vials with Teflon/silicone septa
containing 20 mL of OPW. An extraction blank is also
included in the standard curve. The standards are then
analyzed in the same manner as the samples. The entire
calibration curve is analyzed every 7 days. Two
standards (5 and 20 ,ug/L levels) are analyzed daily and
compared against the established curve. If the results
of the latter standards are not within +/— 10 percent,
the complete standard curve is rerun before calculating
the values of samples (see Section 9.2.3).
8.3 A set of standards in the range of 0.5 to 40 pg/L is
analyzed by GC weekly. Two standards are analyzed each
day prior to the analysis of the samples. These daily
standards are used to verify the accuracy of the
calibration curve. An external standard method is used
to determine the concentration of the samples, utilizing
the current calibration curve. The internal standard is
not used in the quantitation but is used as a reference
peak for peak identification and as an indicator of
injection errors (see Section 9.2.4). A plot of area
versus concentration (in ug/L) is prepared by using a
point—to point fit passing through zero. Calculations
are made from only the linear portions of the curve.
Solvent blanks are run after the standards.
8.4 PFBOA forms a cis and trans oxime with acetaldehyde.
The trans oxime is used for quantitation.
9. QUALITY CONTROL
9.1 MONITORING FOR INTERFERENCES
9.1.1 Laboratory reagent blanks — A laboratory reagent
blank is analyzed each day to verify any
interferences.
9.1.2 Travel blanks for each sampling location are
—6—
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prepared in the laboratory by filling 40-mL vials,
as described above (Section 7.1.3), with OPW.
These are shipped to the sampling site and back to
the laboratory with the sample bottles.
9.1.3 Each reagent bottle of pentane is analyzed before
it is used.
9.2 QUALITY ASSURANCE/QUALITY CONTROL PROTOCOL
The Quality Assurance/Quality Control (QA/QC) protocol
covers accuracy, precision, independent verification and
the use of an internal standard. Accuracy is dependent
on many factors, but the most important is the
calibration curve. Accuracy is monitored by calculating
the recoveries of samples which have been enhanced with
known concentrations of the compounds of interest.
Precision is another parameter that is dependent on more
than one factor. The precision of a method is monitored
by analyzing samples in duplicate and calculating the
normalized difference between the two analyses.
Independent verification of a method is done by
interlaboratory calibration. The internal standard is
used to insure that the GC makes consistent injections
of samples and standards.
All of the above mentioned parameters are important in
assuring that good quality data are produced. It is
important to note that all portions of a QA/QC program
must meet the established standards in order for an
analysis to be considered in control.
9.2.1 Method Detection Limits
Initial calculations of the method detection
limits (MDLs) are made according to the Code of
Federal Regulations 40 part 136, July 1, 1987. A
set of 7 standards are prepared in OPW at 1 to S
times the estimated detection limit. Each
standard is analyzed according to the method and
the standard deviation of the 7 replicate
measurements for each analyte is determined. The
MDL is determined for each analyte as follows:
MDL t (S)
t = 3.143 (student t value for 6 degrees of
freedom and 99 percent confidence level)
S = standard deviation of the 7 replicate analyses
—7—
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These NDLs are used as minimum reporting levels
(NRLs), except where the instrumental detection
limit has proved to be higher. Often, the MRLs
correspond to the lowest level standard on the
calibration curve.
9.2.2 Calibration Curves
Quantitation is done using an external standard
calibration curve. Standards are prepared in OPW
spiked with the aldehydes and extracted with the
same solvent as that used for the samples (see
section 8). The extracted standards are used to
compensate for the varying extraction efficiencies
of the different compounds in the analysis. An
eight—point calibration curve encompassing the 0.5
to 40 pg/L range is used, and two standards are
analyzed each day prior to the analysis of the
samples (see Section 9.2.3).
9.2.2.1 Acceptance/Rejection Criteria
The curve is determined acceptable if the
fit is smooth. Also, the new calibration
curve is compared to the previous curve
to insure that they are comparable. The
injection is determined to be acceptable
if the internal standard is acceptable
(see Section 9.2.4). All internal
standard area counts (pV/seconds) should
be within +/— 10 percent for all
standards in the calibration curve.
9.2.2.2 QC Corrective ction
The problem is determined and corrected.
The calibration curve is reanalyzed on
the GC. If reanalysis does not produce a
satisfactory curve, then a new set of
calibration standards are prepared. The
standards are reanalyzed until an
acceptable curve is obtained. All sample
extracts are reanalyzed from the last
point where calibration curves were in
control. The corrective action is
documented in the formaldehyde notebook
and signed by the immediate supervisor
and QC officer.
9.2.3 Daily Standards
The current calibration curve is verified daily
using the two standards (5 and 20 pg/L levels)
—8—
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analyzed with the sample set.
9.2.3.1 Acceptance/Rejection Criteria
The calculated values of both of the two
daily standards (using the current
calibration curve) must agree to within
+/— 10 percent of their true values.
9.2.3.2 QC Corrective Action
The problem is determined and corrected.
The daily standards are reanalyzed on the
GC. If reanalysis does not produce
satisfactory results, then a new set of
calibration standards are prepared. The
new calibration standards must meet the
criteria in Section 9.2.2. All sample
extracts analyzed with an out—of—control
set of daily standards are recalibrated
utilizing the new calibration curve that
is in control. The corrective action is
documented in the formaldehyde notebook
and signed by the immediate supervisor
and QC officer.
9.2.4 Internal Standard
The internal standard (1,3—dibromopropane) is
spiked directly into each new bottle of solvent at
a concentration of 180 ug/L. (Note, this is not
the same internal standard that is used for the
other disinfection by—product analyses; the
1,2—dibromopropane presents interference problems
for this method.) The solvent is then used to
extract both samples and calibration standards.
The purpose of the internal standard is to monitor
injections made by the autosampler.
9.2.4.1 Acceptance/RejeCtion Criteria
A sample injection is deemed acceptable
if the area counts ( uV/seconds) of the
internal standard peak do not vary more
than ÷/— 10 percent from other samples
which are extracted using the same bottle
of solvent on the same date. The
internal standard areas of samples can
not be compared to those of calibration
standards when the samples and standards
are prepared using extraction solvent
from different bottles or on different
days. The internal standard area can
vary from bottle to bottle and day to
day.
—9—
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9.2.4.2 Corrective Action
The problem is determined and corrected.
The sample extracts are reanalyzed. If
reanalysis is not acceptable, then the
samples are reextracted and reanalyzed.
If the reextracted samples are not
acceptable or the samples have exceeded
the holding time, then the samples are
resampled and reanalyzed or the results
are recorded as suspect and out of
control. Such data are not entered into
the database. The corrective action is
documented in the formaldehyde notebook
and signed by the immediate supervisor
and QC officer.
9.2.5 Spikes
Sample spikes are analyzed to monitor the
extraction efficiency of specific analytes in
sample matrices. This measures the accuracy of
the method in a natural matrix. The spiked
samples are analyzed at a frequency of at least 10
percent of the samples. The spike solution is
prepared in OPW (Section 6.4.2). The samples are
spiked with 10 pL of spike solution to achieve a
concentration of 10 yg/L of each aldehyde, which
are the levels that are typically found in
ozonated waters. Data are entered into the QC
table directly after the analysis. The QC charts
are reviewed by the analyst and the immediate
supervisor.
9.2.5.1 Acceptance/Rejection Criteria
All spike recoveries must fall within the
upper and lower control limits to be
acceptable. Initial control limits are
defined by calculating the mean percent
recovery from the most recent 50 sample
spike data points. The 99 percent
confidence interval is +/— three times
the standard deviation. Warning limits
are defined as +/— two times the standard
deviation. If a sample recovery is above
or below the warning limit this indicates
there is a potential problem. The
problem is determined and corrected
before the analysis is out of control.
Control limits and warning limits are
recalculated on a semiannual basis using
the most recent 50 spiked sample percent
recovery values. Data points that are
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out of control are not included in the
recalculation of new control limits.
Control limits are recalculated when any
major changes are made in the analytical
procedure (i.e. new type of column) and
after at least 20 points have been
collected.
9.2.5.2 QC Corrective Action
The problem is determined and corrected.
The sample extracts and spiked sample
extract are reanalyzed from the point
where the last sample spike recovery was
in control. If the spike recovery is
still not acceptable, then the samples
are reextracted from the point where the
last spike was in control and a sample is
respiked and reanalyzed only for those
analytes that are out of control. If the
spike recovery is not acceptable or
samples have exceeded the holding time,
then the samples are resampled and
reanalyzed from the point where the last
spike was in control. A sample is
respiked and reanalyzed. If reanalysis
is not possible the results are recorded
as suspect for only those analytes that
are out of control. Such data are not
entered into the database. The
corrective action is documented in the
formaldehyde notebook and signed by the
immediate supervisor and QC officer.
9.2.6 Duplicates
Sample duplicates are analyzed in order to monitor
the precision of the method. Duplicates are
analyzed on randomly selected samples at a
frequency of at least 10 percent of the samples.
Data are entered into the QC table within 24 hours
after the analytical run is completed. The QC
charts are reviewed by the analysts and the
immediate supervisor.
9.2.6.1 Acceptance/Rejection Criteria
Control limits are determined by
calculating the range as a function of
the relative standard deviation
(coefficient of variation) as specified
in Standard Methods proposed method
102GB. The range (R) is calculated by
taking the absolute difference of the
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duplicate values as follows:
R = x 1 —x 2 p (x 1 and x 2 are the duplicate
values)
The normalized range (Re) is calculated
by dividing the range (R) by the average
of the duplicate values (xm):
= R
Xm
xl + x 2
Xm _________
2
A mean normalized range (Rm) is
calculated for 50 pairs of duplicate data
points:
ZR
Rm ____
n
n number of duplicate pairs
The variance (s 2 ) of the normalized
ranges is calculated:
E(Rn - Rm) 2
The standard deviation (s) is calculated
as the square root of the variance.
The upper and lower control limits are
defined as R + 3s and zero,
respectively. All duplicates must fall
within the control limits to be
acceptable. The upper warning limit is
defined as + 2s. If an Rfl is outside
the warning limit, this indicates there
is a potential problem. The problem is
investigated before the analysis is out
of control. Control limits are
recalculated on an annual basis using the
most recent 50 points. Data points that
are out of control are not included in
the recalculation of new control limits.
—12—
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Data points below the detection limit
should not be used either. Control
limits are recalculated when any major
changes are made in the analytical
procedure (i.e. new type of column) and
after at least 20 points have been
collected.
9.2.6.2 QC Corrective Action
The problem is determined and corrected.
The sample extracts and the duplicate
extracts are reanalyzed from the point
where the last sample duplicate was in
control. If the duplicate is still not
acceptable, then the samples are
reextracted from the point where the last
duplicates were in control and a
duplicate is reanalyzed only for those
analytes that were out of control. If
the duplicates are still unacceptable or
the sample holding time has been
exceeded, then the samples are resampled
and reanalyzed from the point where the
last duplicates were in control. A
duplicate is reanalyzed. If this is not
possible the results for only those
analytes that were out of control are
recorded as suspect. Such data are not
entered into the database. The
corrective action is documented in the
formaldehyde notebook and signed by the
immediate supervisor and QC officer.
9.2.7 Interlaboratory Calibration
Samples will be split and sent to another
laboratory that is experienced in formaldehyde/
acetaldehyde analysis when available. This will
allow the comparison of results with another
laboratory. This will provide another means of
independent verification. When split samples are
sent a formaldehyde/acetaldehyde spiked sample
will also be sent to verify the quality assurance
of the other laboratory. Results will be recorded
in the formaldehyde notebook.
10. PROCEDURE
10.1 SAMPLE PREPARATION
10.1.1 Samples and standards are removed from storage
and allowed to reach room temperature.
—13—
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10.2 DERIVATIZATION, NICROEXTRACTION AND ANALYSIS
10.2.1 A 20—mL aliquot of sample water is withdrawn
from the sample container by a 20—mt. glass
syringe and delivered to a 30—mt. vial with
Teflon—faced septum and screw cap
(polypropylene, 1—Chem Research, Inc.).
10.2.2 A 1—mL volume of freshly prepared 2 mg/mt. PFBOA
is added to each vial by a Brinkman Dispensette,
capped, and swirled. The sample sits at room
temperature for 2 hours +/— 5 minutes.
10.2.3 The sample is quenched by adding 0.05 mL
(approximately 2 drops) of concentrated H 2 S0 4
and swirled. A 4—mt. volume of pentane
(containing the internal standard) is added to
the vial by a Brinkman Dispensette and the vial
is then capped.
10.2.4 After all the vials have been sealed and
prepared for extraction, they are placed in a
vial holder and shaken for 5 minutes in a
mechanical shaker.
10.2.5 The vials are removed from the vial holder,
placed upright and allowed to stand for S
minutes. Equal volumes of extract are
transferred into two 1.5—mt. autosampler vials by
a pasteur pipet.
10.2.6 At the beginning of each analytical run, a
pentane solvent blank is injected to condition
the GC and to verify that no interferences are
present.
10.2.7 The data are collected on a Hewlett Packard
model 300 microcomputer (Palo Alto, Calif.) with
Nelson Analytical Xtrachrome chromatography
software (Cupertino, Calif.). Autosampler
information (rack* & vial*) is communicated to
the data system for sample identification
purposes. The data files are designated ZSXXXXY
where ZS is a code designating the formaldehdye/
acetaldehyde analysis, XXXX is the month and day
in numbers and Y is a unique sequential cycle
number assigned to each data file by the data
system. The data files are archived to magnetic
tape.
10.2.8 See Table 1 for retention times.
—14—
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TABLE 1
METHOD DETECTION LIMITS (MDLs),
MINIMUM REPORTING LEVELS (MRLs),
AND RETENTION TIMES (RTs)
NDLs MRLs RTs
Compounds ( pg/L) ( pg/L) ( mm )
1, 3_Dibromopropanea 10.54
Formaldehyde (HCHO) 0.87 1.0 11.85*
Acetaldehyde 5 (CH 3 CHOcI 5 )* 0.55 1.0 15.23*
Acetaldehydetrans (CH3CHOtrans) 4 0.64 1.0 15.62*
alnternal standard.
*These are the retention times of the derivatized oximes
formed by the PFBOA.
Aceta1dehyde forms cis and trans oximes with the PFBOA.
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TABLE 2
GAS-CHROMATOGRAPHIC CONDITIONS
Column
Type: Fused silica capillary
(Durabond—5, J&W Scientific, Folsom, Calif.)
Length: 30 meters
Internal diameter: 0.25 millimeters
Film thickness: 1.0 micron
Temperature program
50°C > 122°C > 245°c
1 mm 8 0 C/min 7 mm 30°C/mm 2 mm
Injector
Injection volume: 2 pL
Temperature: 150°C
Splitless injection: Split valve opened at 0.5 mm
Detector
Type: Electron capture
Temperature: 272°C
Gases
Carrier: Helium (99.999 percent purity)
Flow: 1.5 mL/min at 25°C
Makeup: Nitrogen (99.999 percent purity)
Flow: 24 mL/min
Autosampler Parameters — (for Varian model 8035 autosampler)
Purge pulse pressure 55 psi
number of purge
pulses 1
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TABLE 3
ANALYTI CAL STANDARDS
Molec— Boiling
Purity ular Point
Compound Source ( percent) Weight ( °C) Density
Formaldehyde Aidricha * 30.03 96 1.083
Acetaldehyde Chem svcb 44.05 21 0.788
aAldrich Chemical Company, Inc., Milwaukee, Wisc.
bchem Service, Inc., Westchester, Pa.
*Formaldehyde available as a 37 weight percent solution in water.
-------
J James M. Montgomery
Consulting Engineers. inc.
I
Appendix D
Correlation Matrices
-------
CORRELATION ANALYSES
THMs
CHCI3 CHCI2Br CHBr2CI
CHBr3 -0.305 0.032 0.578
THMs CHBr2CI 0.001 0.659
CHCI2Br 0.606
THMs
CHCI3 CHC12Br CHBr2CI CHBr3
TCAA 0.802 0.397 -0.131 -0.314
DCAA 0.860 0.538 -0.030 -0.326
MCAA 0.649 0.519 0.050 -0.192
MBAA -0.054 0.4 14 0.767 0.608
DBAA -0.222 0.229 0.785 0.8 16
THMs
CHCI3 CHCI2Br CHBr2CI CHBr3
TCAN 0.343 0.183 -0.088 -0.106
HANs DCAN 0.740 0.508 0.017 -0.241
SCAN 0.341 0.833 0.770 0.244
DBAN -0.250 0.227 0.756 0.880
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CORRELATION ANALYSES
THMs
CHCI3 CHCI2Br CHBr2CI CHBr3
HKs 1,FDCP 0.330 0.084 -0.260 0.397
1,1,1-TCP 0.520 0.124 -0.195 -0.286
THMs
CHCI 3 CHCL2Br CHBr2CI CHBr3
CHP 0.491 0.253 -0.130 -0.305
MISC CH 0.846 0.657 0.129 -0.236
CNCI 0.046 0.084 -0.025 -0.160
THMs
CHCI3 CHCI2Br CHBr2CI CHBr3
FRM 0.150 0.159 0.099 -0.095
ALDs
ACETAL 0.223 0.377 0.25 1 -0.052
-------
CORRELATION ANALYSES
THMs
CHCI3 CHCI2Br CHBr2CI CHBr3
TOC 0.502 0.513 0.189 -0.087
INFLUENT UV 0.436 0.403 0.178 -0.067
PARAMETERS -
C l -0.246 -0.006 0.289 0.629
Br -0.250 -0.073 0.180 0.566
HAAS
TCAA DCAA MCAA MBAA
DBAA -0.277 -0.233 -0.099 0.8 18
MBAA -0.122 -0.056 0.079
HAAs
MCAA 0.59 1 0.726
DCAA 0.854
HAAs
TCAA DCAA MCAA MBAA DBAA
TCAN 0.575 0.426 0.355 -0.038 -0.142
HANs DCAN 0.762 0.616 0.502 -0.065 -0.171
BCAN 0.213 0.265 0.312 0.565 0.516
DBAN -0.306 -0.280 -0.132 0.739 0.850
-------
CORRELATION ANALYSES
TCAA DCAA
HAAS
MCAA MBAA DBAA
1,1-DCP
HKs
1,1,1-TCP
0.508
0.770
0.559
0.659
0.441
0.369
. .O.259
-0.142
-0.387
-0.284
HAM
TCAA DCAA MCAA
MBAA DBAA
0.397
0.536
0.385
-0.160
-0.273
0.660
0.741
0.594
0.040
-0.114
0.115
0.184
0.283
0.058
-0.104
FRM
ALDs
ACETAL
HAM
TCAA DCAA MCAA MBAA DI3AA
CHP
MISC
CH
CNCI
0.070 0.210
0.126 0.301
0.333 0.107 -0.016
0.422 0.234 0.076
-------
CORRELATION ANALYSES
HAM
TCAA DCAA MCAA MBAA DBAA
INFLUENT
PARAMETERS
TOC
Uv
CL
Br
0.278
0.578
0.560
0.132
0.046
0.222
0.488
0.589
0.152
0.079
-0.273
-0.259
-0.110
0.476
0.668
-0.272
-0.267
-0.076
0.389
0.600
DRAN
HANs BCAN
DCAN
HANs
TCAN DCAN
-0.103 -0.174
0.163 0.469
0.504
1,1-DCP
HKs
1,1,1-TCP
BCAN
0.517
HANs
TCAN DCAN BCAN DBAN
0.456 0.392
0.67 1 0.496
-0.041 -0.417
0.032 -0.288
-------
CORRELATION ANALYSES
HANs
TCAN DCAN BCAN DBAN
CHP 0.218 0.277 0.048 -0.293
MISC
CH 0.452 0.619 0.449 -0.140
CNCI 0.173 0.330 0.096 -0.159
HANs
TCAN DCAN BCAN DBAN
ALDS FRM -0.028 0.153 0.066 -0.067
ACETAL 0.108 0.256 0.321 0.047
HANs
TCAN DCAN SCAN DBAN
TOC 0.105 0.264 0.323 -0.008
INFLUENT U” ’ 0.041 0.279 0.351 0.012
PARAMETERS -
Cl -0.066 -0.164 0.210 0.587
Br -0.100 -0.178 0.119 0.485
-------
CORRELATION ANALYSES
HKs
1,1-DCP
HKs 1,1,1-TCP 0.595
MISC
CHP
CH
CNCI
HKs
1,1-DCP 1,1,1-TCP
HKs
1,1-DCP 1,1,1-TCP
FRM 0.380
ALDS
ACETAL 0.352
MISC
0.009
-0.009
HKs
1,1-DCP 1,l l-TCP
0.340
0.280
-0.3 11
-0.298
0.096
0.052
-0.238
-0 .256
CNCI
MISC
CH
CHP
FRM
ALDs
ACETAL
0.373
0.279
0.471
0.355
0.528
-0.021
INFLUENT
PARAMETERS
TOC
Uv
C I
Br
CH
0.289
0.503
-0.045
MISC
CHP CH CNCI
0.348
0.4 16
0.174 0.319
0.328 0.592
-------
CORRELATION ANALYSES
MISC
CHP CH CNCI
TOC 0.353 0.360 0.338
UV 0.243 0.259 0.308
INFLUENT -
PARAMETERS C I -0.226 -0.178 -0.112
Br -0.218 -0.210 -0.103
ALDs
FRM ACETAL
ALDs TOC 0.237 0.352
FRM INFLUENT UV 0.298 0.303
ALDs ACETALI 0.638 PARAMETERS CI -0.134 -0.062
Br -0.109 -0.072
INFLUENT PARAMETERS
TOC UV CI
Br 0.054 0.064 0.967
INFLUENT
PARAMETERS CI 0.057 0.042
N 0.793 * without Utility 10, r = 0.854
# without Utility 30,4th qurter, r = 0.872
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