EPA Document #: EPA/600/R-14/442
METHOD 530 DETERMINATION OF SELECT SEMIVOLATILE ORGANIC
CHEMICALS IN DRINKING WATER BY SOLID PHASE
EXTRACTION AND GAS CHROMATOGRAPHY/ MASS
SPECTROMETRY (GC/MS)
Version 1.0
January, 2015
Paul E. Grimmett
NATIONAL EXPOSURE RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U. S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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METHOD 530
DETERMINATION OF SELECT SEMIVOLATILE ORGANIC CHEMICALS IN
DRINKING WATER BY SOLID PHASE EXTRACTION AND GAS
CHROMATOGRAPHY/ MASS SPECTROMETRY (GC/MS)
1. SCOPE AND APPLICATION
1.1. This is a gas chromatography/mass spectrometry (GC/MS) method for the
determination of selected semivolatile organic compounds in drinking waters.
Accuracy and precision data have been generated in reagent water, and in finished
ground and surface waters for the compounds listed in the table below. This method
was initially developed with full scan GC/MS, but performance has also been
demonstrated in the selected ion monitoring (SIM) mode for all analytes. SIM is useful
when enhanced sensitivity is desirable. An example chromatogram which includes the
entire analyte list is shown in Fig. 1.
Analyte
o-toluidine
quinoline
butylated hydroxyanisole (BHA)
dimethipin
Chemical Abstract Services
Registry Number (CASRN)
95-53-4
91-22-5
25013-16-5
55290-64-7
1.2. The Minimum Reporting Level (MRL) is the lowest analyte concentration that meets
Data Quality Objectives (DQOs) that are developed based on the intended use of this
method. The single laboratory lowest concentration MRL (LCMRL) (Sect. 3.12) is
the lowest true concentration for which the future recovery is predicted to fall, with
high confidence (99 percent), between 50 and 150 percent recovery. The LCMRL is
compound dependent and is also dependent on extraction efficiency, sample matrix,
fortification concentration, and instrument performance. The procedure used to
determine the LCMRL is described elsewhere.1'2 During method development,
LCMRLs were determined from the results of laboratory fortified blanks (LFBs) in
full scan mode and in the SIM mode for all method analytes. These LCMRLs are
provided in Tables 5 and 9 for full scan and SIM modes, respectively.
1.3. Laboratories using this method are not required to determine the LCMRL for this
method, but will need to demonstrate that their laboratory MRL for this method
meets the requirements described in Sect. 9.2.4.
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1.4. Determining the Detection Limit (DL) for analytes in this method is optional
(Sect. 9.2.6). Detection limit is defined as the statistically calculated minimum
concentration that can be measured with 99% confidence that the reported value is
greater than zero.3 The DL is compound dependent and is also dependent on
extraction efficiency, sample matrix, fortification concentration, and instrument
performance. DLs have been determined for all analytes in full scan mode (Table 5)
and in SIM mode (Table 9).
1.5. This method is intended for use by analysts skilled in solid phase extractions, the
operation of GC/MS instruments, and the interpretation of the associated data.
1.6. METHOD FLEXIBILITY - In recognition of technological advances in analytical
systems and techniques, the laboratory is permitted to modify the GC inlet, inlet
conditions, column, injection parameters, and all other GC and MS conditions.
Changes may not be made to sample collection and preservation (Sect. 8), sample
extraction (Sect. 11) or to the Quality Control (QC) requirements (Sect. 9). Method
modifications should be considered only to improve method performance.
Modifications that are introduced in the interest of reducing cost or sample
processing time, but result in poorer method performance, should not be used. In all
cases where method modifications are proposed, the analyst must perform the
procedures outlined in the initial demonstration of capability (IDC, Sect. 9.2), verify
that all QC acceptance criteria in this method (Sect. 9) are met, and that method
performance in real sample matrices is equivalent to that demonstrated for
Laboratory Fortified Sample Matrices (LFSMs) in Sect. 17.
Note: The above method flexibility section is intended as an abbreviated summation
of method flexibility. Sects. 4-12 provide detailed information of specific portions of
the method that may be modified. If there is any perceived conflict between the
general method flexibility statement in Sect. 1.6 and specific information in Sects.
4-12, Sects. 4-12 supersede Sect. 1.6.
2. SUMMARY OF METHOD
2.1. A 1-liter water sample is fortified with surrogate analytes and passed through a solid
phase extraction (SPE) device (Sects. 6.9-6.11) to extract the target analytes and
surrogates. The compounds are eluted from the solid phase with a small amount of
organic solvents. The solvent extract is dried by passing it through a column of
anhydrous sodium sulfate, concentrated by evaporation with nitrogen gas, and then
adjusted to a 1-mL volume with dichloromethane after adding the internal standards.
A splitless injection is made into a GC equipped with a high-resolution fused silica
capillary column that is interfaced to an MS. The analytes are separated and
identified by comparing the acquired mass spectra and retention times to reference
spectra and retention times for calibration standards acquired under identical GC/MS
conditions. The GC/MS may be operated in the full scan, SIM, or selected ion
storage (SIS) mode (Sects 3.19 and 3.20). The GC/MS may be calibrated using
standards prepared in solvent or using matrix-matched standards (Sects. 3.15 and
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7.2.4). The concentration of each analyte is calculated by using its integrated peak
area and the internal standard technique. Surrogate analytes are added to all Field
and Quality Control (QC) Samples to monitor the performance of each extraction
and overall method performance.
2.2 Butylated hydroxyanisole (BHA) can be affected by matrix induced chromatographic
response enhancement (Sect. 3.14), when analyzed at low concentrations. Refer to
Sect. 13 for information regarding method performance.
3. DEFINITIONS
3.1. ANALYSIS BATCH - A set of samples that is analyzed on the same instrument
during a 24-hour period that begins and ends with the analysis of the appropriate
Continuing Calibration Check (CCC) Standards. Additional CCCs may be required
depending on the length of the analysis batch and/or the number of Field Samples.
3.2. CALTERATION STANDARD (CAL) - A solution prepared from the primary
dilution standard solution or stock standard solution(s) and the internal standards and
surrogate analytes. The CAL solutions are used to calibrate the instrument response
with respect to analyte concentration. In this method, traditional CAL standards
prepared in dichloromethane (DCM) may be used or matrix-matched standards (Sect.
3.15) prepared in a concentrated laboratory reagent water (LRW) extract may be
used. This procedure is described in Sect. 7.2.4.2.
3.3. CONTINUING CALIBRATION CHECK (CCC) STANDARD - A calibration
standard containing one or more method analytes, which is analyzed periodically to
verify the accuracy of the existing calibration for those analytes.
3.4. DETECTION LIMIT (DL) - The minimum concentration of an analyte that can be
identified, measured and reported with 99% confidence that the analyte
concentration is greater than zero. This is a statistical determination (Sect. 9.2.6), and
accurate quantitation is not expected at this level.3
3.5. EXTRACTION BATCH - A set of up to 20 Field Samples (not including QC
samples) extracted together by the same person(s) during a work day using the same
lot of solid phase extraction devices, solvents, surrogate solution, and fortifying
solutions. Required QC samples include Laboratory Reagent Blank, Laboratory
Fortified Blank, Laboratory Fortified Sample Matrix, and either a Field Duplicate or
Laboratory Fortified Sample Matrix Duplicate.
FIELD DUPLICATES (FD1 and FD2) - Two separate samples collected at the same
time and place under identical circumstances, and treated exactly the same
throughout field and laboratory procedures. Analyses of FD1 and FD2 provide an
estimate of the precision associated with sample collection, preservation, and
storage, as well as with laboratory procedures.
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3.7. INTERNAL STANDARD (IS) - A pure compound added to an extract or standard
solution in a known amount and used to measure the relative responses of the
method analytes and surrogates.
3.8. LABORATORY FORTIFIED BLANK (LFB) - An aliquot of reagent water or other
blank matrix to which known quantities of the method analytes and all the
preservation compounds are added. The LFB is processed and analyzed exactly like
a sample, and its purpose is to determine whether the methodology is in control, and
whether the laboratory is capable of making accurate and precise measurements.
3.9. LABORATORY FORTIFIED SAMPLE MATRIX (LFSM) - An aliquot of a Field
Sample to which known quantities of the method analytes and all the preservation
compounds are added. The LFSM is processed and analyzed exactly like a sample,
and its purpose is to determine whether the sample matrix contributes bias to the
analytical results. The background concentrations of the analytes in the sample
matrix must be determined in a separate aliquot and the measured values in the
LFSM corrected for background concentrations.
3.10. LABORATORY FORTIFIED SAMPLE MATRIX DUPLICATE (LFSMD) - A
duplicate Field Sample used to prepare the LFSM, which is fortified, extracted and
analyzed identically to the LFSM. The LFSMD is used instead of the Field Duplicate
to assess method precision and accuracy when the occurrence of a method analyte is
infrequent.
3.11. LABORATORY REAGENT BLANK (LRB) - An aliquot of reagent water that i s
treated exactly as a sample including exposure to all glassware, equipment, solvents,
reagents, sample preservatives, internal standards, and surrogates that are used in the
extraction batch. The LRB is used to determine if method analytes or other
interferences are present in the laboratory environment, the reagents, or the
extraction apparatus.
3.12. LOWEST CONCENTRATION MINIMUM REPORTING LEVEL (LCMRL) - The
single-laboratory LCMRL is the lowest true concentration for which the future
recovery is predicted to fall, with high confidence (99 percent), between 50 and 150
percent recovery.1'2
3.13. MATERIAL SAFETY DATA SHEET (MSDS) - Written information provided by
vendors concerning a chemical's toxicity, health hazards, physical properties, fire,
and reactivity data including storage, spill, and handling precautions.
3.14. MATRIX-INDUCED CHROMATOGRAPHIC RESPONSE ENHANCEMENT
(MICRE) - This phenomenon occurs when, in the absence of matrix components,
method analytes in calibration solutions are degraded or absorbed in the GC injector
or column, resulting in poor peak shapes and low response. When subsequent sample
extracts containing the analytes and components from a complex sample matrix are
injected, peak shape and response improve. In this situation, quantitative data for
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field samples may exhibit a high bias.4"11 Generally, overestimation of results is
more pronounced at low analyte concentrations.
3.15. MATRIX-MATCHED CALTERATION STANDARD - A calibration standard that
is prepared by adding method analytes to a concentrated extract of a matrix (reagent
water is used for this method) that has been prepared following all the extraction and
sample preparation steps of the analytical method. The material extracted from the
matrix reduces matrix-induced response enhancement effects and improves the
quantitative accuracy of sample results.10'11
3.16. MINIMUM REPORTING LEVEL (MRL) - The minimum concentration that can be
reported by a laboratory as a quantitated value for a method analyte in a sample
following analysis. This concentration must meet the criteria defined in Sect. 9.2.4
and must not be any lower than the concentration of the lowest continuing calibration
check standard for that analyte. The MRL may be determined by the laboratory
based upon project objectives, or may be set by a regulatory body as part of a
compliance monitoring program.
3.17. PRIMARY DILUTION STANDARD SOLUTION (PDS) - A solution containing
method analytes, internal standards, or surrogate analytes prepared in the laboratory
from stock standard solutions and diluted as needed to prepare calibration solutions
and other analyte solutions.
3.18. QUALITY CONTROL SAMPLE (QCS) - A solution prepared using a PDS of
method analytes obtained from a source external to the laboratory and different from
the source of calibration standards. The second source PDS and the surrogate PDS
are used to fortify the QCS at a known concentration. The QCS is used to verify the
accuracy of the primary calibration standards.
3.19. SELECTED ION MONITORING (SIM) - An MS technique where only one or a
few ions are monitored for each target analyte. When used with gas chromatography,
the set of ions monitored is usually changed periodically throughout the
chromatographic run, to correlate with the characteristic ions of the analytes, SURs
and ISs as they elute from the chromatographic column. The technique is often used
to increase sensitivity. Throughout this document, the term "SIM" will be used to
include both SIM as described here and SIS as described in Sect. 3.20.
3.20. SELECTED ION STORAGE (SIS) - An MS technique typically associated with ion
trap mass spectrometers in which only one or a few ions are stored at any given time
point. When used with gas chromatography, the set of ions stored is usually changed
periodically throughout the chromatographic run, to correlate with the characteristic
ions of the analytes, SURs and ISs as they elute from the chromatographic column.
SIS can be used to enhance sensitivity. Throughout this document the term "SIM"
will be used to include both SIM (Sect. 3.19) and SIS.
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3.21. STOCK STANDARD SOLUTION (SSS) - A concentrated solution containing one
or more method analytes prepared in the laboratory using assayed reference materials
or purchased from a reputable commercial source.
3.22. SURROGATE ANALYTE (SUR) - A pure analyte, which is extremely unlikely to
be found in any sample, and which is added to a sample aliquot in a known amount
before extraction or other processing, and is measured with the same procedures used
to measure other sample components. The purpose of the SUR is to monitor method
performance with each sample. In this method, the SURs are isotopically labeled
analogues of selected method analytes.
4. INTERFERENCES
4.1. All glassware must be meticulously cleaned. Wash glassware with detergent and tap
water, rinse with tap water, followed by reagent water. Rinse with methanol and/or
acetone. Non-volumetric glassware may be heated in a muffle furnace at 400 °C for
two hours as a substitute for solvent rinsing. Volumetric glassware should not be
heated in an oven above 120 °C.
4.2. Method interferences may be caused by contaminants in solvents, reagents
(including reagent water), sample bottles and caps, and other sample processing
hardware that lead to discrete artifacts and/or elevated baselines in the chromato-
grams. All items such as these must be routinely demonstrated to be free from
interferences (less than Vs the MRL for each target analyte) under the conditions of
the analysis by analyzing laboratory reagent blanks as described in Sect. 9.3.1.
Subtracting blank values from sample results is not permitted.
4.3. Matrix interferences may be caused by contaminants that are co-extracted from the
sample. The extent of matrix interferences will vary considerably from source to
source, depending upon the nature of the water. Water samples high in total organic
carbon (TOC) may have elevated baselines or interfering peaks. Matrix components
may directly interfere by producing a signal at or near the retention time of an
analyte peak. They can also enhance the signal of method analytes (Sect. 3.14).
Analyses of LFSMs are useful in identifying matrix interferences.
4.4. Relatively large quantities of the buffer and preservatives (Sect. 8.1.2) are added to
sample bottles. The potential exists for trace-level organic contaminants in these
reagents. Interferences from these sources should be monitored by analysis of
laboratory reagent blanks, particularly when new lots of reagents are acquired.
4.5. Solid phase extraction media have been observed to be a source of interferences.12
The analysis of laboratory reagent blanks can provide important information
regarding the presence or absence of such interferences. Brands and lots of solid
phase extraction devices should be tested to ensure that contamination does not
preclude analyte identification and quantitation.
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4.6. Analyte carryover may occur when a relatively "clean" sample is analyzed
immediately after a sample (or standard) that contains relatively high concentrations
of compounds. Syringes and GC injection port liners must be cleaned carefully or
replaced as needed. After analysis of a sample (or standard) that contains high
concentrations of compounds, a laboratory reagent blank should be analyzed to
ensure that accurate values are obtained for the next sample.
4.7. Silicone compounds may be leached from punctured autosampler vial septa,
particularly when particles of the septa are present in the vial for an extended time.
This can occur after repeated injections from the same autosampler vial. These
silicone compounds, which appear as regularly spaced chromatographic peaks with
similar MS fragmentation patterns, can unnecessarily complicate the total ion
chromatograms and may cause interferences at high levels.
4.8. In cases where the SPE disks or cartridges are dried by pulling room air through the
media using vacuum, it may be possible for the media to become contaminated by
components in room air. This was not observed during method development, but if
laboratories encounter contamination problems associated with room air, compressed
gas cylinders of high purity nitrogen may be used for drying SPE media during
sample processing.
5. SAFETY
5.1. The toxicity or carcinogenicity of each reagent used in this method has not been
precisely defined. Each chemical should be treated as a potential health hazard, and
exposure to these chemicals should be minimized. Each laboratory is responsible for
maintaining an awareness of OSHA regulations regarding safe handling of chemicals
used in this method. A reference file of MSDSs should be made available to all
personnel involved in the chemical analysis. Additional references to laboratory
safety are available.13"15
5.2. Pure standard materials and stock standard solutions of these compounds should be
handled with suitable protection to skin and eyes, and care should be taken not to
breathe the vapors or ingest the materials.
6. EQUIPMENT AND SUPPLIES
References to specific brands or catalog numbers are included for illustration only, and do
not imply endorsement of the product. Other brands of equivalent quality may be used. The
SPE sorbents described in Sect. 6.9 are proprietary products that have been fully evaluated
for use in this method. Due to their proprietary status, some chemistry aspects of the sorbents
are unknown, making equivalency difficult to determine. The EPA document "Technical
Notes on Drinking Water Methods"16 provides criteria for judging equivalency of SPE
products (pg. 47). Before analyses are performed for compliance under the Safe Drinking
Water Act, questions regarding equivalency of alternate sorbent materials must be addressed
to the Office of Ground Water and Drinking Water Alternate Test Procedure Coordinator.17
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6.1. SAMPLE CONTAINERS - 1 -L or 1 -qt amber glass bottles fitted with
polytetrafluoroethylene (PTFE)-lined screw caps are preferred. Clear glass bottles
with PTFE-lined screw caps may be substituted if sample bottles are wrapped with
foil, stored in boxes, or otherwise protected from light during sample shipping and
storage.
6.2. VIALS - Various sizes of amber glass vials with PTFE-lined screw caps for storing
standard solutions and extracts. Amber glass 2-mL autosampler vials with PTFE-
faced septa.
6.3. VOLUMETRIC FLASKS - Class A, suggested sizes include 1, 5, and 10 mL for
preparation of standards and dilution of extract to final volume.
6.4. GRADUATED CYLINDERS - Suggested sizes include 5, 10, 250 and 1000 mL.
6.5. MICRO SYRINGES - Suggested sizes include 10, 25, 50, 100, 250, 500, and
1000 |iL.
6.6. DRYING COLUMN - The drying column must be able to contain 7-8 g of
anhydrous sodium sulfate (Na2SO4). The drying column should not leach interfering
compounds or irreversibly adsorb method analytes. Any small glass or
polypropylene column may be used, such as Supelco #57176.
6.7. COLLECTION TUBES - 15 mL, conical tubes (Fisher #05-569-3) or other
glassware suitable for collection of the eluent from the solid phase sorbent after
extraction and for collecting extract from drying tube.
6.8. ANALYTICAL BALANCE - Capable of weighing to the nearest 0.0001 g.
6.9. SPE APPARATUS USING SPE CARTRIDGES (6-mL COLUMNS); MANUAL
EXTRACTION
6.9.1. SPE CARTRIDGES - Modified DVB or PS/DVB polymer
6.9.1.1. Waters Oasis HLB, 500 mg (Waters #186000115)-
divinylbenzene N-vinylpyrrolidone copolymer
6.9.1.2. Phenomenex Strata-X, 500 mg (Phenomenex #8B-S100-HCH) -
polystyrene divinylbenzene N-vinylpyrrolidone copolymer
6.9.1.3. Agilent Mega Bond Elut Plexa, 500 mg (Agilent #12259506)-
hydrophilic polystyrene divinylbenzene polymer
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6.9.2. VACUUM EXTRACTION MANIFOLD - Equipped with flow/vacuum
control (Supelco #57030-U or equivalent).
6.9.3. SAMPLE DELIVERY SYSTEM - Use of a transfer tube system (Supelco
"Visiprep", #57275 or equivalent), which transfers the sample directly from
the sample container to the SPE cartridge is recommended.
6.9.4. An automatic or robotic system designed for use with SPE cartridges may
be used if all quality control requirements discussed in Sect. 9 are met.
Automated systems may use either vacuum or positive pressure to process
samples and solvents through the cartridge. All sorbent washing,
conditioning, sample loading, rinsing, drying and elution steps must be
performed as closely as possible to the manual procedure. The solvents used
for washing, conditioning, and sample elution must be the same as those
used in the manual procedure: however, the amount used may be increased
as necessary to achieve the required data quality. Solvent amounts may not
be decreased. Sorbent drying times prior to elution may be modified to
achieve the required data quality. Caution should be exercised when
increasing solvent volumes. Increased extract volume will likely necessitate
the need for additional sodium sulfate drying, and extended evaporation
times which may compromise data quality. Caution should also be
exercised when modifying sorbent drying times. Excessive drying may
cause losses due to analyte volatility, and excessive contact with room air
may oxidize some method analytes. Insufficient drying may leave excessive
water trapped in the disk and lead to poor recoveries.
6.10. EXTRACT CONCENTRATION SYSTEM - Extracts are concentrated by
evaporation with nitrogen gas using a water bath set at 40 °C (N-Evap, Model 11155,
Organomation Associates, Inc., or equivalent).
6.11. LABORATORY OR ASPIRATOR VACUUM SYSTEM - Sufficient capacity to
maintain a vacuum of approximately 15 to 25 inches of mercury.
6.12. GAS CHROMATOGRAPH/MASS SPECTROMETER (GC/MS) SYSTEM
6.12.1. FUSED SILICA CAPILLARY GC COLUMN - 30 m x 0.25-mm inside
diameter (i.d.) fused silica capillary column coated with a 0.25 jim bonded
film of cyanopropyl phenyl and dimethylpolysiloxane (RestekRtx-1701 or
equivalent). Any capillary column that provides adequate capacity,
resolution, accuracy, and precision may be used. A mid-polar, low-bleed
column is recommended for use with this method to provide adequate
resolution and minimize column bleed.
6.12.2. GC INJECTOR AND OVEN - Some of the target compounds included in
this method are subject to thermal breakdown in the GC injection port. This
problem is exacerbated when the injector and/or the injection port liner is
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not properly deactivated or is operated at excessive temperatures. The
injection system must not allow analytes to contact hot stainless steel or
other metal surfaces that promote decomposition. The performance data in
Sect. 17 were obtained using hot, splitless injection using a 4 or 5-mm i.d.
glass deactivated liner. Other injection techniques such as temperature
programmed injections, cold on-column injections and large volume
injections may be used if the QC criteria in Sect. 9 are met. Equipment
designed appropriately for these alternate types of injections must be used if
these options are employed.
6.12.3. GC/MS INTERFACE - The interface should allow the capillary column or
transfer line exit to be placed within a few millimeters of the ion source.
Other interfaces are acceptable as long as the system has adequate
sensitivity and QC performance criteria are met.
6.12.4. MASS SPECTROMETER (MS) - Any type of MS may be used (i.e.,
quadrupole, ion trap, time of flight, etc.) with electron ionization. The
instrument may be operated in full scan mode or in SIM mode for enhanced
sensitivity. The minimum scan range capability of the MS must be 45 to
450 m/z, and it must produce a full scan mass spectrum that meets all
criteria in Table 2 when a solution containing 5 ng (or less) of
decafluorotriphenylphosphine (DFTPP) is injected into the GC/MS
(Sect. 10.2.1).
6.12.5. DATA SYSTEM - An interfaced data system is required to acquire, store,
and output MS data. The computer software should have the capability of
processing stored GC/MS data by recognizing a GC peak within a given
retention time window. The software must allow integration of the ion
abundance of any specific ion between specified time or scan number
limits. The software must be able to construct linear regressions and
quadratic calibration curves, and calculate analyte concentrations.
7. REAGENTS AND STANDARDS SUPPLIES (References to specific brands or catalog
numbers are included for illustration only, and do not imply endorsement of the product.)
7.1. REAGENTS AND SOLVENTS - Reagent grade or better chemicals should be used
in all tests. Unless otherwise indicated, it is intended that all reagents will conform to
the specifications of the Committee on Analytical Reagents of the American
Chemical Society (ACS), where such specifications are available. Other grades may
be used, if the reagents are demonstrated free of analytes and interferences, and all
method requirements in the Initial Demonstration of Capability (IDC) are met.
7.1.1. HELIUM - 99.999 % or better, GC carrier gas. Alternate carrier gases, such as
hydrogen (99.999 % or better) may be used if the QC criteria in Sect. 9 are
met. Instrument manufacturers should be consulted prior to any GC carrier gas
conversion.
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7.1.2. LABORATORY REAGENT WATER (LRW) - Purified water which does
not contain any measurable quantities of any target analytes or interfering
compounds at or above l/3 the MRL for each compound of interest.
7.1.3. METHANOL (MeOH) (CASRN 67-56-1) - High purity, demonstrated to be
free of analytes and interferences (Fisher Optima or equivalent).
7.1.4. DICHLOROMETHANE (DCM) (CASRN 75-09-02) - High purity,
demonstrated to be free of analytes and interferences (Fisher GC Resolv or
equivalent).
7.1.5. ACETONE (CASRN 67-64-1) - High purity, demonstrated to be free of
analytes and interferences (Tedia Absolv or equivalent).
7.1.6. SODIUM SULFATE (Na2SO4), ANHYDROUS (CASRN 7757-82-6) -
Soxhlet extracted with DCM for a minimum of four hours or heated to
400 °C for two hours in a muffle furnace. An "ACS grade, suitable for
pesticide residue analysis," is recommended.
7.1.7. SAMPLE PRESERVATION REAGENTS - The following preservatives
are solids at room temperature and may be added to the sample bottle before
shipment to the field.
7.1.7.1. BUFFER SALT MIX, pH 7 - The sample must be buffered to
pH 7 with two components: 1) tris(hydroxymethyl)aminomethane,
also called Tris, 0.47 g (CASRN 77-86-1, ACS Reagent Grade or
equivalent); and 2) tris(hydroxymethyl)aminomethane
hydrochloride, also called Tris HC1, 7.28 g (CASRN 1185-53-1,
ACS Reagent Grade or equivalent). Alternately, 7.75 g of a
commercial buffer crystal mixture, that is blended in proportion to
the amounts given above (Sigma-Aldrich #T7193 or equivalent),
can be used.
7.1.7.2. L-ASCORBIC ACID (CASRN 50-81-7) - Ascorbic acid reduces
free chlorine at the time of sample collection (ACS Reagent Grade
or equivalent).
7.1.7.3. ETHYLENEDIAMINE TETRAACETIC ACID (EDTA),
TRISODIUM SALT (CASRN 10378-22-0) - Trisodium EDTA is
added to inhibit metal-catalyzed hydrolysis of analytes.
7.1.7.4. DIAZOLIDINYL UREA (DZU) (CAS# 78491-02-8) - DZU is
added to inhibit microbial growth.
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STANDARD SOLUTIONS - Standard solutions of internal standards, surrogates
and method analytes may be prepared gravimetrically or from commercially
available stock solutions. When a compound purity is assayed to be 96% or greater,
the weight can be used without correction to calculate the concentration of a
gravimetrically prepared stock standard. Solution concentrations listed in this section
were those used to develop this method and are included as an example only.
Solution preparation steps may be modified as needed to meet the needs of the
laboratory. Often, standard mixes appropriate to the method become commercially
available subsequent to method publication. Even though stability times for
standard solutions are suggested in the following sections, laboratories should
use standard QC practices to determine when their standards need to be
replaced. In addition, signs of evaporation and/or discoloration are indicators
that a standard should be replaced.
7.2.1.
7.2.2.
INTERNAL STANDARD (IS) SOLUTIONS - This method uses two IS
compounds listed in the table below. A commercial mixture of ISs was used
for method development, and it is highly recommended that other analysts
use a commercial mix as well. However, if an analyst chooses to prepare a
gravimetric stock solution, it should be prepared in acetone using a
procedure similar to the preparation of analyte stocks as outlined in Sect.
7.2.3.1. The PDS mix for ISs has been shown to be stable for at least one
year when stored in amber glass screw cap vials at -5 °C or less. Using
10 jiL of the IS to fortify the final 1-mL extracts (Sect. 11.5) will yield a
concentration of 5 |ig/mL each for ISs for full scan analysis. Lower
concentrations of ISs should be used for SIM analysis. For SIM analysis
during method development, ISs were added to extracts such that their final
concentration was 500 ng/mL.
Note: Stock standard solutions and PDSs should be brought to room
temperature and sonicated for a few minutes prior to use. This ensures that
components are dissolved and the solution is homogeneous.
Internal Standards
acenaphthene-t/io (IS 1)
phenanthrene-t/io (IS 2)
CASRN
15067-26-2
1517-22-2
Solvent
acetone
acetone
PDS cone.
500 |ig/mL
500 |ig/mL
SURROGATE ANALYTE STANDARD SOLUTIONS - The surrogate
analytes used in this method are listed in the table below. All SUR PDSs
were used at the same concentration and were prepared in methanol. The
SURs may be prepared from neat material or purchased (if available from
commercial suppliers) as individual PDSs or a single PDS. For method
development, neat material was purchased from CDN Isotopes
(o-toluidine-dg, #D-3571) and Cambridge Isotopes (quinoline-J?,
#DLM-1158-0.1). The SUR PDSs have been shown to be stable for at least
530-13
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one year when stored in amber glass screw cap vials at -5 °C or less. For full
scan analysis, 10 jiL of each of these solutions was added to each 1L
aqueous QC and Field Sample prior to extraction, for an expected final
extract concentration of 5 |ig/L of each SUR. For SIM analysis, the QC and
Field Samples were fortified such that the expected final extract
concentration was 500 ng/L for each SUR.
Surrogates
o-toluidine-db (SUR 1)
quinoline-J? (SUR 2)
CASRN
194423-47-7
34071-94-8
Solvent
methanol
methanol
PDS cone.
500 |ig/mL
500 |ig/mL
Notes:
• Stock standard solutions and PDSs should be brought to room
temperature and sonicated for a few minutes prior to use. This ensures
that components are dissolved and the solution is homogeneous.
• Stock standard solutions that will be used for aqueous sample
fortification generally should be prepared at a concentration such that
only a small volume (e.g., 5-100 jiL) needs to be added to achieve the
desired final concentration. This will minimize the quantity of organic
solvent added to aqueous samples.
7.2.3. ANALYTE STOCK SOLUTIONS
7.2.3.1. ANAL YTE STOCK STANDARD SOLUTIONS (SSS)
(5.0 mg/mL) - Analyte standards may be purchased commercially
as ampulized solutions prepared from neat materials.
Commercially prepared SSSs are widely available for most method
analytes. To prepare gravimetric stock standard solutions, add
10 mg (weighed on analytical balance to 0.1 mg) of the pure
material to 1.9 mL of methanol in a 2-mL volumetric flask, dilute
to the mark, and transfer the solution to an amber glass vial. If the
neat material is only available in quantities less than 10 mg, reduce
the volume of solvent accordingly. If compound purity is
confirmed by the supplier to be > 96%, the weighed amount can be
used without correction to calculate the concentration of the
solution. Store at 4 °C or less to guard against degradation and
evaporation.
Note: Stock standard solutions and PDSs should be brought to
room temperature and sonicated for a few minutes prior to use.
This ensures that components are dissolved and the solution is
homogeneous.
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7.2.3.2. ANALYTE PRIMARY DILUTION STANDARD (100 jig/mL) -
Prepare the 100-|ig/mL Analyte PDS by volumetric dilution of the
Analyte Stock Standard Solutions (Sect. 7.2.3.1) in methanol to
make a 100-|ig/mL solution. The PDS can be used to fortify the
LFBs and LFSMs with method analytes and to prepare calibration
solutions. Care should be taken during storage to prevent
evaporation. The Analyte PDS Solutions used during method
development were stable for 6 months stored in an amber glass
screw cap vials at -5 °C or less.
Notes:
• Two separate Analyte PDS mixtures should be prepared: one
PDS for o-toluidine and quinoline, and one PDS for BHA and
dimethipin. Method development work exhibited degradation
of o-toluidine in PDS mixtures with multiple analytes at high
concentrations.
• Fortification generally should be prepared at a concentration
such that only a small volume (e.g., 5-100 jiL) needs to be
added to achieve the desired final concentration. This will
minimize the quantity of organic solvent added to aqueous
samples.
• Stock standard solutions and PDSs should be brought to room
temperature and sonicated for a few minutes prior to use. This
ensures that components are dissolved and the solution is
homogeneous.
7.2.4. CALIBRATION SOLUTIONS - Calibration standards may be prepared in
DCM or as matrix-matched calibration standards (Sect. 3.15). This option is
provided so that the analyst has the flexibility to prepare calibration curves
that will be appropriate for the various types of analytes and the calibration
range of interest. If the analyses to be performed include only those analytes
that are not susceptible to matrix induced response enhancement, and/or the
concentrations to be measured are relatively high (e.g., > 5|ig/L), it is likely
that accurate data can be obtained with the use of traditional CAL standards
prepared in DCM. If low concentrations of analytes susceptible to matrix
induced response enhancement need to be measured, it is likely that matrix-
matched standards will be required to obtain accurate quantitative data.
Whichever type of CAL solutions are selected, those CAL solutions should
be used for all calibration and QC procedures described in the method.
Note: Analytes observed to be susceptible to matrix induced response
enhancement during method development are indicated in the "comments"
portion of Table 1. However, the occurrence and degree of enhancement
will depend upon the GC injector design, and the history of the injector,
injector liner and GC column. It is highly recommended that prior to the
initial demonstration of capability, separate calibration curves be generated
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using DCM CALs and matrix-matched CALs for each analyte to be
measured. A careful evaluation of the relative peak areas using each type of
CAL, especially low concentration CALs, can serve as a guide to the
possible occurrence and extent of matrix enhancement, and thus an
indicator of which type of standards should be used.
7.2.4.1. CALIBRATION SOLUTIONS PREPARED IN SOLVENT -
Prepare a series of six concentrations of calibration solutions in
DCM, which contain the analytes of interest. The suggested
concentrations in this paragraph are a description of the
concentrations used during method development, and may be
modified to conform with instrument sensitivity. For full scan
analyses, concentrations ranging from 0.10-5.0 ng/uL are
suggested for each analyte, with IS and SUR concentrations as
described in Sect. 7.2.1 and 7.2.2. For SIM analysis, six
concentrations in the range of 0.005-0.5 ng/uL are suggested, with
reduced concentrations of the ISs and SURs (Sect. 7.2.1 and 7.2.2).
The six CAL standards (CAL1 through CAL6) are prepared by
combining appropriate aliquots of the Analyte PDS solution (Sect.
7.2.3.2) and the IS and SURPDSs (Sects. 7.2.1. and 7.2.2). All
calibration solutions should contain at least 60% DCM to avoid gas
chromatographic anomalies such as poor peak shape, split peaks,
etc. During method development, all analytes were prepared in a
single set of calibration solutions. Calibration solutions were stable
for six months when stored at -5 °C in amber screw top vials.
7.2.4.2. MATRIX-MATCHED CALIBRATION SOLUTIONS - Prepare a
series of six calibration solutions in the same manner as in Sect.
7.2.4.1, but instead of preparation in DCM, calibration solutions
are prepared in final solvent extracts derived from laboratory
reagent water. One-liter aliquots of reagent water with sample
preservatives added, are extracted using the sorbent selected for
sample analysis, dried with sodium sulfate, and evaporated to
<1 mL following the same procedure used for samples (Sects.
11.3-11.5). However, the ISs, SURs, and analyte PDSs are
added to the extract at appropriate concentrations
immediately before the adjustment of the extract to 1 mL, i.e.,
they are not extracted.
7.2.5. GC/MS TUNE CHECK SOLUTION (5 |ig/mL or less)
(CASRN 5074-71-5) - Prepare a DFTPP solution in DCM. Store this
solution in an amber glass screw cap vial at 4 °C or less.
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8. SAMPLE COLLECTION, PRESERVATION, AND STORAGE
8.1. SAMPLE BOTTLE PREPARATION
8.1.1. Grab samples must be collected using 1-liter or 1-quart sample bottles that
meet the requirements in Sect. 6.1.
8.1.2. Preservation reagents, listed in the table below, are added to each sample
bottle as dry solids prior to shipment to the field (or prior to sample
collection).
Compound
L- Ascorbic acid
Ethylenediaminetetraacetic acid, trisodium
salt
Diazolidinyl Urea
*Tris(hydroxymethyl)aminomethane
*Tris(hydroxymethyl)aminomethane
hydrochloride
Amount
O.lOg/L
0.35 g/L
1.0 g/L
0.47 g/L
7.28 g/L
Purpose
Dechlorination
Inhibit metal -catalyzed
hydrolysis of targets
Microbial inhibitor
First component of pH 7
buffer mixture
Second component of pH
7 buffer mixture
* Alternately, 7.75 g of a commercial buffer crystal mixture, that is blended in
the proportions given in the table, can be used (Sect. 7.1.7.1).
8.1.2.1. Residual chlorine must be reduced at the time of sample collection
with 100 mg of ascorbic acid per liter.
8.1.2.2. Trisodium EDTA must be added to inhibit potential metal-
catalyzed hydrolysis of method analytes.
8.1.2.3. Diazolidinyl urea (1.0 g) is added to inhibit microbial degradation
of analytes.
8.1.2.4. The sample must be buffered to pH 7 to reduce the acid and base
catalyzed hydrolysis of target analytes. The pH buffer has two
components: tris(hydroxymethyl)aminomethane (0.47 g) and
tris(hydroxymethyl)aminomethane hydrochloride (7.28 g). A
commercially prepared combination of these two compounds can
be purchased as pre-mixed crystals. When using the pH 7
pre-mixed crystals, add 7.75 g per liter of water sample.
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8.2. SAMPLE COLLECTION
8.2.1. Open the tap and allow the system to flush until the water temperature has
stabilized (usually 3-5 min). Collect samples from the flowing system.
8.2.2. Fill sample bottles, taking care not to flush out the sample preservation
reagents. Samples do not need to be collected headspace free.
8.2.3. After collecting the sample, cap the bottle and agitate by hand until
preservatives are dissolved. Immediately place in ice or refrigerate.
8.3. SHIPMENT AND STORAGE - Samples must be chilled during shipment and must
not exceed 10 °C during the first 48 hours after collection. Sample temperature must
be confirmed to be at or below 10 °C when they are received at the laboratory, with
the following exception. Samples arriving at the laboratory on the day of sampling
may not have had time to achieve a temperature of less than 10 °C. This is acceptable
as long as the cooling process has begun. Samples stored in the lab must be held at or
below 6 °C until extraction, but should not be frozen. Sample holding time data are
discussed in Sect. 13.3.
Note: Samples that are significantly above 10 °C at the time of collection, may need
to be iced or refrigerated for a period of time, in order to chill them prior to shipping.
This will allow them to be shipped with sufficient ice to meet the above
requirements.
8.4. SAMPLE AND EXTRACT HOLDING TIMES - Water samples should be extracted
as soon as possible after collection but must be extracted within 14 days of
collection. All extracts must be stored at -5 °C or less, protected from light and
analyzed within 14 days after extraction (Sect. 13.4).
9. QUALITY CONTROL
9.1. QC requirements include the Initial Demonstration of Capability (IDC) and ongoing
QC requirements that must be met when preparing and analyzing Field Samples.
This section describes QC parameters, their required frequency, and the performance
criteria that must be met in order to meet EPA quality objectives. The QC criteria
discussed in the following sections are summarized in Tables 10 and 11. These QC
requirements are considered the minimum acceptable QC criteria. Laboratories are
encouraged to institute additional QC practices to meet their specific needs.
9.2. INITIAL DEMONSTRATION OF CAPABILITY - The IDC must be successfully
performed prior to analyzing any Field Samples. Prior to conducting the IDC, the
analyst must first generate an acceptable Initial Calibration following the procedure
530-18
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outlined in Sect. 10.2. The IDC must be repeated if the laboratory changes the
type or brand of SPE sorbent being used.
9.2.1. INITIAL DEMONSTRATION OF LOW SYSTEM BACKGROUND -
Any time a new lot of SPE cartridges or disks is used, it must be
demonstrated that a Laboratory Reagent Blank is reasonably free of
contamination and that the criteria in Sect. 9.3.1 are met.
9.2.2. INITIAL DEMONSTRATION OF PRECISION (IDP) - Prepare, extract,
and analyze four to seven replicate LFBs fortified near the midrange of the
initial calibration curve according to the procedure described in Sect. 11.
Sample preservatives as described in Sect. 8.1.2 must be added to these
samples. The relative standard deviation (RSD) of the results of the
replicate analyses must be < 20%.
9.2.3. INITIAL DEMONSTRATION OF ACCURACY - Using the same set of
replicate data generated for Sect. 9.2.2, calculate average recovery. The
average recovery expressed as the mean of the replicate values must be
within 70-130 % of the true value for all analytes except o-toluidine, which
must be within 50-130% of the true value.
9.2.4. MINIMUM REPORTING LEVEL (MRL) CONFIRMATION - Establish a
target concentration for the MRL based on the intended use of the method.
The MRL may be established by a laboratory for their specific purpose or
may be set by a regulatory agency. Establish an Initial Calibration following
the procedure outlined in Sect. 10.2. The lowest calibration standard used to
establish the Initial Calibration (as well as the low-level Continuing
Calibration Check standard) must be at or below the concentration of the
MRL. Establishing the MRL concentration too low may cause repeated
failure of ongoing QC requirements. Confirm the MRL following the
procedure outlined below.
9.2.4.1. Fortify, extract, and analyze seven replicate Laboratory Fortified
Blanks (LFBs) at the proposed MRL concentration. These LFBs
must contain all method preservatives described in Sect. 8.1.2.
Calculate the mean and standard deviation for these replicates.
Determine the Half Range for the Prediction Interval of Results
(HRpiR) using the equation below
HRPIR = 3.9635
where:
S = the standard deviation, and 3.963 is a constant value for seven
replicates.1
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9.2.4.2. Confirm that the upper and lower limits for the Prediction Interval
of Result (PIR = Mean + HR.PIR) meet the upper and lower
recovery limits as shown below:
The Upper PIR Limit must be <150 percent recovery.
Fortified Concentration
The Lower PIR Limit must be > 50 percent recovery.
Mean-HRPIR
Fortified Concentration
9.2.4.3. The MRL is validated if both the Upper and Lower PIR Limits
meet the criteria described above (Sect. 9.2.4.2). If these criteria
are not met, the MRL has been set too low by the laboratory and
must be demonstrated again at a higher concentration. If a required
MRL set by a regulatory body has not been met, the analyst should
evaluate possible problems in the execution of the extraction steps,
and/or possible problems with instrument sensitivity. Reattempt
MRL validation at the required MRL after problems have been
addressed.
9.2.4.4. Confirmation of the MRL Using Fortified Matrix Samples
(optional)- This validation procedure may be used in addition to
the reagent water confirmation described above. It may be useful
in assessing any matrix induced quantitative bias at the MRL.
Obtain replicate 1 L aliquots of a water sample similar in nature to
the ones planned for analysis. If tap waters from both ground and
surface water sources are to be analyzed, it is recommended that a
surface water sample be selected for verification. Analyze one
aliquot using the procedures in this method to verify the absence of
analytes of interest. Fortify seven remaining aliquots with the
analytes to be measured near the expected MRL, and verify the
MRL as described in Sects. 9.2.4.1 through 9.2.4.3.
9.2.5. CALIBRATION CONFIRMATION - Analyze a Quality Control Sample as
described in Sect. 9.3.9 to confirm the accuracy of the standards/calibration
curve.
9.2.6. DETECTION LIMIT DETERMINATION (optional) - While DL
determination is not a specific requirement of this method, it may be
required by various regulatory bodies associated with compliance
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monitoring. It is the responsibility of the laboratory to determine ifDL
determination is required based upon the intended use of the data.
Replicate analyses for this procedure should be done over at least three days
(both the sample extraction and the GC analyses should be done over at
least three days). Prepare at least seven replicate LFBs at a concentration
estimated to be near the DL. This concentration may be estimated by
selecting a concentration at 2-5 times the noise level. The DLs in Tables 5
and 9 were calculated from LFBs fortified at various concentrations as
indicated in the table. The appropriate fortification concentrations will be
dependent upon the sensitivity of the GC/MS system used. All preservation
reagents listed in Sect. 8.1.2 must also be added to these samples. Analyze
the seven (or more) replicates through all steps of Sects. 11 and 12.
Note: If an MRL confirmation data set meets these requirements, a DL may
be calculated from the MRL confirmation data, and no additional analyses
are necessary.
Calculate the DL using the following equation:
Ls_/_J J A. t / -1 -1 y-\ /~\/~\\
(w-1, l-or=0.99)
where:
t («-i, i-a=o.99) = Student's t value for the 99% confidence level with n-1
degrees of freedom
n = number of replicates
s = standard deviation of replicate analyses.
Note: Do not subtract blank values when performing DL calculations.
9.3. ONGOING QC REQUIREMENTS - This section summarizes the ongoing QC
criteria that must be followed when processing and analyzing Field Samples.
9.3.1. LABORATORY REAGENT BLANK (LRB) - An LRB is required with
each extraction batch of up to 20 Field Samples to confirm that potential
background contaminants are not interfering with the identification or
quantitation of target analytes. If the LRB produces a peak within the
retention time window of any analyte that would prevent the determination
of that analyte, locate the source of contamination and eliminate the
interference before processing samples. Background contamination must be
reduced to an acceptable level before proceeding. Background from method
analytes or other contaminants that interfere with the measurement of
method analytes must be at or below lh of the MRL. Blank contamination
may be estimated by extrapolation, if the concentration is below the lowest
calibration standard. Although this procedure is not allowed for sample
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results as it may not meet data quality objectives, it can be useful in
estimating background concentrations. If any of the method analytes are
detected in the LRB at concentrations greater than l/3 of the MRL, then all
data for the problem analyte(s) must be considered invalid for all samples in
the extraction batch.
Note: It is extremely important to evaluate background values of analytes
that commonly occur in LRBs. The MRL must be set at a value greater than
three times the mean concentration observed in replicate LRBs. If LRB
values are highly variable, setting the MRL to a value greater than the mean
LRB concentration plus three times the standard deviation may provide a
more realistic MRL.
9.3.2. CONTINUING CALIBRATION CHECK (CCC) - CCC Standards are
analyzed at the beginning of each analysis batch, after every ten Field
Samples, and at the end of the analysis batch. See Sect. 10.3 for
concentration requirements and acceptance criteria.
9.3.3. LABORATORY FORTIFIED BLANK (LFB) - An LFB is required with
each extraction batch of up to 20 Field Samples. The fortified concentration
of the LFB must be rotated between low, medium, and high concentrations
from batch to batch. The low concentration LFB must be as near as
practical to, but no more than two times the MRL. Similarly, the high
concentration LFB should be near the high end of the calibration range
established during the initial calibration (Sect. 10.2). Results of the low-
level LFB analyses must be 50-150% of the true value. Results of the
medium and high-level LFB analyses must be 70-130% of the true value for
all analytes except o-toluidine, which may be between 50-130% of the true
value. If the LFB results do not meet these criteria for target analytes, then
all data for the problem analyte(s) must be considered invalid for all sam-
ples in the extraction batch.
9.3.4. MS TUNE CHECK - A complete description of the MS Tune Check is
found in Sect. 10.2.1. The acceptance criteria for the MS Tune Check are
summarized in Table 2. The MS Tune Check must be performed each time
a major change is made to the mass spectrometer, and prior to establishing
and/or re-establishing an initial calibration (Sect. 10.2). Daily DFTPP
analysis is not required.
Note: The tune check is performed in full scan mode, even if samples will
be analyzed in SIM mode.
9.3.5. INTERNAL STANDARDS (IS) - The analyst must monitor the peak areas
of the ISs in all injections during each analysis day. The peak area for each
IS in any chromatographic run must not deviate by more than ±50% from
the mean response in the CAL solutions analyzed for the initial analyte
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calibration. In addition, the peak areas of ISs must not deviate by more than
± 30% from the most recent CCC. If the IS areas in a chromatographic run
do not meet these criteria, inject a second aliquot of that standard or extract.
9.3.5.1. If the reinjected aliquot produces acceptable internal standard
responses, report results for that aliquot.
9.3.5.2. If the reinjected aliquot is a sample extract and fails again, the
analyst should check the calibration by evaluating the CCCs within
the analysis batch. If the CCCs are acceptable, extraction of the
sample may need to be repeated provided the sample is still
available and within the holding time. Otherwise, report results
obtained from the reinjected extract, but annotate as "suspect/IS
area." Alternatively, collect a new sample and reanalyze.
9.3.5.3. If the reinjected aliquot is a CAL standard, take remedial action
(Sect. 10.3.3).
9.3.6. SURROGATE RECOVERY - Surrogate standards are fortified into the
aqueous portion of all samples, LRBs, LFBs, CCCs, LFSMs, and LFSMDs
prior to extraction. They are also added to the calibration standards. The
surrogates are a means of assessing method performance from extraction to
final chromatographic measurement. Calculate the recovery (%R) for each
surrogate using the equation
%# = ( —1x100
UJ
where:
A = measured surrogate concentration for the QC or Field Sample, and
B = fortified concentration of the surrogate.
9.3.6.1. Surrogate recovery must be within 70-130% of the true value for
quinoline-J? and within 50-130% for o-toluidine-dg. When
surrogate recovery from a sample, blank, or CCC is outside the
acceptable range, check 1) calculations to locate possible errors, 2)
the integrity of the surrogate analyte solution, 3) contamination,
and 4) instrument calibration. Correct the problem and reanalyze
the extract.
9.3.6.2. If the extract reanalysis meets the surrogate recovery criterion,
report only data for the reanalyzed extract.
9.3.6.3. If the extract reanalysis fails the recovery criterion, the analyst
should check the calibration by evaluating the CCCs within the
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analysis batch. If the CCCs fail the criteria of Sect. 9.3.6.1,
recalibration is in order per Sect. 10.2. If the calibration standard is
acceptable, extraction of the sample should be repeated, provided
the sample is still available and within the holding time. If the re-
extracted sample also fails the recovery criterion, report all data for
that sample as "suspect/surrogate recovery" to inform the data user
that the results are suspect due to surrogate recovery.
9.3.7. LABORATORY FORTIFIED SAMPLE MATRIX (LFSM) - Within each
analysis batch of up to 20 Field Samples, analyze a minimum of one LFSM. The
native concentrations of the analytes in the sample matrix must be determined in a
second duplicate sample and subtracted from the measured values in the LFSM. If
a variety of different sample matrices are analyzed regularly, for example,
drinking water from ground water and surface water sources, performance data
must be collected for each source.
9.3.7.1. Prepare the LFSM by fortifying a Field Duplicate with an
appropriate amount of analyte PDS (Sect. 7.2.3.2). Select a
fortification concentration that is greater than or equal to the matrix
background concentration, if known. Selecting a duplicate sample
that has already been analyzed aids in the selection of an
appropriate fortification concentration. If this is not possible, use
historical data. If historical data are unavailable, rotate the
fortifying concentrations for LFSMs between low, medium and
high concentrations based on the calibration range.
9.3.7.2. Calculate the percent recovery (%R) for each analyte using the
equation
C
where:
A = measured concentration in the fortified sample
B = measured concentration in the unfortified sample
C = fortification concentration.
Note: LFSMs and LFSMDs fortified at concentrations near the
MRL, where the associated Field Sample contains native analyte
concentrations above the DL but below the MRL, should be
corrected for the native levels in order the obtain meaningful %R
values. This example, and the LRB extrapolation (Sect. 9.3.1), are
the only permitted uses of analyte results below the MRL.
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9.3.7.3. Analyte recoveries may exhibit matrix bias. For samples fortified
at or above their native concentration, recoveries should be within
70-130% (50-130% for o-toluidine), except for low-level
fortification near or at the MRL (within a factor of two times the
MRL concentration) where 50-150% recoveries are acceptable. If
the accuracy of any analyte falls outside the designated range, and
the laboratory performance for that analyte is shown to be in
control in the CCCs, the recovery is judged to be matrix biased.
The quantitative result for that analyte in the unfortified sample is
labeled "suspect/matrix" to inform the data user that the
quantitative results may be suspect due to matrix effects.
9.3.8. FIELD DUPLICATE OR LABORATORY FORTIFIED SAMPLE
MATRIX DUPLICATE (FD or LFSMD) - Within each extraction batch,
analyze a minimum of one Field Duplicate (FD) or Laboratory Fortified
Sample Matrix Duplicate (LFSMD). Duplicates check the precision
associated with sample collection, preservation, storage, and laboratory
procedures. If target analytes are not routinely observed in Field Samples,
an LFSMD should be analyzed rather than an FD.
9.3.8.1. Calculate the relative percent difference (RPD) for duplicate
measurements (FD1 and FD2) using the equation
xlOO
(FD\ + FD2)/2
9.3.8.2. RPDs for Field Duplicates should be < 30 %. Greater variability
may be observed when Field Duplicates have analyte
concentrations that are within two times the MRL. At these
concentrations, Field Duplicates should have RPDs that are < 50%.
If the RPD of any analyte falls outside the designated range, and
the laboratory performance for that analyte is shown to be in
control in the CCC, the recovery is judged to be affected by the
matrix. The result for that analyte in the unfortified sample is
labeled "suspect/matrix" to inform the data user that the
quantitative results may be suspect due to matrix effects.
9.3.8.3. If an LFSMD is analyzed instead of a Field Duplicate, calculate the
relative percent difference (RPD) for duplicate LFSMs (LFSM and
LFSMD) using the equation
\LFSM -LFSMDl
RPD = -^ - J- x 100
(LFSM + LFSMD)/ 2
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9.3.8.4. RPDs for duplicate LFSMs should be < 30% for samples fortified
at or above their native concentration. Greater variability may be
observed when LFSMs are fortified at analyte concentrations that
are within two times the MRL. LFSMs fortified at these
concentrations should have RPDs that are < 50% for samples
fortified at or above their native concentration. If the RPD of any
analyte falls outside the designated range, and the laboratory
performance for that analyte is shown to be in control in the CCC,
the recovery is judged to be affected by the matrix. The result for
that analyte in the unfortified sample is labeled "suspect/matrix" to
inform the data user that the quantitative results may be suspect
due to matrix effects.
9.3.9. QUALITY CONTROL SAMPLES (QCS) - As part of the IDC (Sect. 9.2),
each time a new Analyte PDS (Sect. 7.2.3.2) or CAL solutions (7.2.4) are
prepared, or at least quarterly, analyze a QCS sample from a source
different from the source of the calibration standards. If a second vendor is
not available then a different lot of the standard should be used. The QCS
should be prepared and analyzed just like a CCC. Acceptance criteria for
the QCS are identical to the CCCs; the calculated amount for each analyte
must be ± 30% of the expected value. If measured analyte concentrations
are not of acceptable accuracy, check the entire analytical procedure to
locate and correct the problem. If the discrepancy is not resolved, one of the
standard materials may be degraded or otherwise compromised and a third
standard must be obtained.
9.4. METHOD MODIFICATION QC REQUIREMENTS - The analyst is permitted to
modify GC columns, GC conditions, GC injection techniques, extract evaporation
techniques, MS conditions and quantitation ions (QIs). However, each time such
method modifications are made, the analyst must repeat the procedures of the IDC
(Sect. 9.2).
9.4.1. Each time method modifications are made, the analyst must repeat the
procedures of the IDC (Sect. 9.2) and verify that all QC criteria can be met
in ongoing QC samples (Sect. 9.3).
9.4.2. Each time method modifications are made, the analyst is also required to
evaluate and document method performance for the proposed method
modifications in real matrices that span the range of waters that the
laboratory analyzes. This additional step is required because modifications
that perform acceptably in the IDC, which is conducted in reagent water,
can fail ongoing method QC requirements in real matrices. This is
particularly important for methods subject to matrix effects. If, for example,
the laboratory analyzes finished waters from both surface and groundwater
municipalities, this requirement can be accomplished by assessing precision
and accuracy (Sects. 9.2.2 and 9.2.3) in an analyte fortified surface water
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with moderate to high TOC (e.g., 2 mg/L or greater) and an analyte fortified
hard groundwater (e.g., 250 mg/L or greater as calcium carbonate).
9.4.3. The results of Sects. 9.4.1 and 9.4.2 must be appropriately documented by
the analyst and should be independently assessed by the laboratory's
Quality Assurance (QA) officer prior to analyzing Field Samples. When
implementing method modifications, it is the responsibility of the
laboratory to closely review the results of ongoing QC, and in particular, the
results associated with the LFSMs (Sect. 9.3.7), FDs or LFSMDs
(Sect. 9.3.8), CCCs (Sect. 9.3.2), and the IS area counts (Sect. 9.3.5). If
repeated failures are noted, the modification must be abandoned.
10. CALIBRATION AND STANDARDIZATION
10.1. Demonstration and documentation of acceptable mass spectrometer tune and initial
calibration is required before performing the IDC and prior to analyzing Field
Samples. The MS tune check and initial calibration must be repeated each time a
major instrument modification is made, or maintenance is performed.
10.2. INITIAL CALIBRATION
10.2.1. MS TUNE/MS TUNE CHECK - Calibrate the mass and abundance scales
of the MS with calibration compounds and procedures prescribed by the
manufacturer with any modifications necessary to meet tuning
requirements. Inject 5 ng or less of the DFTPP solution (Sect. 7.2.5) into the
GC/MS system. Acquire a mass spectrum that includes data for m/z 45 to
450. The scan time should be set so that a minimum of five scans are
acquired during the elution of the chromatographic peak. Seven to ten scans
per chromatographic peak are recommended. Use a single spectrum at the
apex of the DFTPP peak, an average spectrum of the three highest points of
the peak, or an average spectrum across the entire peak to evaluate the
performance of the system. If the DFTPP mass spectrum does not meet all
criteria in Table 2, the MS must be retuned and adjusted to meet all criteria
before proceeding with the initial calibration. The tune check should be
conducted as described above for both full scan and SIM MS operation.
10.2.2. INSTRUMENT CONDITIONS - Operating conditions used during method
development are described below. Conditions different from those
described may be used if QC criteria in Sect. 9 are met. Different conditions
include alternate GC columns, temperature programs, MS conditions, and
injection techniques and volumes, such as cold on-column and large volume
injections. Equipment specifically designed for alternate types of injections
must be used if these alternate options are selected.
10.2.2.1. GC Conditions - Inject a l-|iL aliquot into a hot, splitless injection
port held at 275 °C with a pressure pulse of 20 psi and a split delay
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of 1 min. The temperature program is as follows: initial oven
temperature of 60 °C, hold for 1 min, ramp at 10 °C/min to a final
temperature of 290 °C and hold for 1 min. The GC is operated at a
constant carrier gas flow rate of 1 mL/min. Total run time is
approximately 25 min. Begin data acquisition at about seven min.
10.2.2.2. Full Scan MS Acquistion Parameters - Select a scan range that
allows the acquisition of a mass spectrum for each of the method
analytes, which includes all of the major fragments m/z 45 and
above. Adjust the cycle time to measure at least five spectra during
the elution of each GC peak. Seven to ten scans across each GC
peak are recommended. The chromatogram may be divided into
time windows, also known as segments or periods, with different
scan ranges for each time window. Minimizing the scan range for
each time window may enhance sensitivity. If the chromatogram is
divided into time windows, the laboratory must ensure that each
method analyte elutes entirely within the proper window during
each analysis. This can be achieved by carefully monitoring the
retention times of all ISs and SURs in each sample, and carefully
monitoring the retention times of all method analytes in CCCs,
LFBs and LFSMs. This requirement does not preclude continuous
operation by sequencing multiple analysis batches; however, the
entire analysis batch is invalid if one or more analyte peaks have
drifted outside of designated time windows in the CCC at the
beginning or end of the analysis batch.
10.2.2.3. SIM MS Acquistion Parameters - Prior to selecting SIM
parameters, analyze a mid- to high-concentration CAL in full scan
mode. Select one primary QI and at least one secondary ion for
confirmation. Suggested QIs and secondary ions for all method
analytes are designated in Table 1, but these may be modified. An
internal standard for each analyte is also designated in Table 1.
Verify that the primary ion is free from interferences due to an
identical fragment ion in any overlapping peak(s). Selection of the
QI should be based on the best compromise between the intensity
of the signal for that ion and the likelihood and intensity of
interferences. The most intense ion may not be the best QI.
However, the QI and secondary ions must be >30% relative
abundance. Adjust the cycle time to measure at least five spectra
during the elution of each GC peak. If the chromatogram is divided
into time windows, the laboratory must ensure that each method
analyte elutes entirely within the proper window during each
analysis. This can be achieved by carefully monitoring the
retention times of all ISs and SURs in each sample, and carefully
monitoring the retention times of all method analytes in CCCs,
LFBs and LFSMs. This requirement does not preclude continuous
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operation by sequencing multiple analysis batches; however, the
entire analysis batch is invalid if one or more analyte peaks have
drifted outside of designated time windows in the CCC at the
beginning or end of the analysis batch. The SIM parameters used
during method development for selected analytes are provided in
Table 6 as an example.
10.2.2.4. Alternating Full and SIM Scan Modes - Alternating full and SIM
scan modes during a single sample acquisition is permitted if the
minimum number of scans across each GC peak acquired in each
mode is maintained (as specified in Sect. 10.2.2.2 and 10.2.2.3),
i.e., a minimum of five scans in full scan mode and a minimum of
five scans in SIM mode. If the chromatogram is divided into time
windows, the laboratory must ensure that each method analyte
elutes entirely within the proper window during each analysis. This
can be achieved by carefully monitoring the retention times of all
ISs and SURs in each sample, and carefully monitoring the
retention times of all method analytes in CCCs, LFBs and LFSMs.
This requirement does not preclude continuous operation by
sequencing multiple analysis batches; however, the entire analysis
batch is invalid if one or more analyte peaks have drifted outside of
designated time windows in the CCC at the beginning or end of the
analysis batch.
10.2.3. CALIBRATION SOLUTIONS - To establish a calibration range extending
two orders of magnitude, prepare a set of at least six calibration standards as
described in Sect. 7.2.4. The lowest concentration CAL must be at or below
the MRL for each method analyte. The MRL must be confirmed using the
procedure outlined in Sect. 9.2.4 after establishing the initial calibration.
Note: This method contains analytes that vary with regard to instrument
sensitivity. If the analytes of interest differ in response, and the CAL
standards have been prepared such that all analytes are at the same
concentration, more standards may be needed to obtain the minimum six
CAL points for each analyte. Analytes with poor response may not be
observed in the low concentration standards, and the most responsive
analytes may saturate the detector at the higher concentrations. It is likely
that the calibration range for all analytes will not be the same. The use of
custom calibration standards with varying analyte concentrations based on
their relative instrument response is a possible alternative.
10.2.4. CALIBRATION - Calibrate the GC/MS system using the internal standard
technique in either full scan, SIM or alternating full scan/SEVI mode.
Subsequent sample analysis must be performed in the same calibration
mode using identical instrument conditions and parameters. Internal
standard designations and suggested QIs for all method analytes are listed in
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Table 1. Table 6 contains example scanning parameters for selected
analytes in SIM mode. Linear or quadratic calibrations may be used.
Weighting may be used at the discretion of the analyst.
10.2.5. CALIBRATION ACCEPTANCE CRITERIA - Validate the initial
calibration curves by using the regression equations to calculate the
concentration of each analyte as an unknown in each of the analyses used to
generate the curves. Calibration points that are < MRL must calculate to be
within ± 50% of their true value. All other calibration points must calculate
to be within ± 30% of their true value. If these criteria cannot be met, the
analyst may eliminate either the highest or lowest point on the curve and
reassess the acceptance criteria. If the acceptance criteria still cannot be
met, the analyst will have difficulty meeting ongoing QC criteria. It is
highly recommended that corrective action be taken before proceeding.
This may include one or more of the following actions: analyze the
calibration standards, further restrict the range of calibration, or select an
alternate method of calibration. The data presented in this method were
obtained using either linear regression or quadratic fits. Quadratic fit
calibrations should be used with caution, because the non-linear area of the
curve may not be reproducible.
10.3. CONTINUING CALIBRATION CHECK (CCC) - Analyze a CCC to verify the
initial calibration at the beginning of each analysis batch, after every tenth Field
Sample, and at the end of each analysis batch. The beginning CCC for each analysis
batch must be at or below the MRL. This CCC verifies instrument sensitivity prior to
the analysis of samples. Alternate subsequent CCCs between the remaining
calibration levels.
Note: If standards have been prepared such that all analytes are not in the same
calibration standard (or all low CAL points are not in the same CAL standard), it
may be necessary to analyze more than one CCC to meet this requirement.
Alternatively, it may be cost effective to prepare or obtain a customized standard to
meet this criterion.
10.3.1. Verify that the peak area of the QI of each IS has not changed by more than
± 50% from the mean peak area measured for that IS during initial
calibration. In addition, verify that the peak area of the QI of each of the
two ISs are within ± 30% from the most recently analyzed CCC. If these
limits are exceeded, remedial action must be taken (Sect. 10.3.3). Control
charts are useful aids in documenting system sensitivity changes.
10.3.2. Calculate the concentration of each analyte and surrogate in the CCC. The
calculated amount for each analyte for medium and high level CCCs must
be ± 30% of the true value. The calculated amount for the lowest calibration
level for each analyte must be within ± 50% of the true value. If these
criteria are not met, then all data for the problem analyte must be considered
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invalid, and remedial action (Sect. 10.3.3) must be taken. Recalibration may
be required. Any Field Sample extracts that have been analyzed since the
last acceptable calibration verification should be reanalyzed after adequate
calibration has been restored, with the following exception. If the CCC at
the end of an analysis batch fails because the calculated concentration is
greater than 130% (150% for the low-level CCC) for a particular target
analyte, and Field Sample extracts show no detection for that target
compound, non-detects may be reported without reanalysis.
10.3.3. REMEDIAL ACTION - Failure to meet CCC QC performance criteria may
require remedial action. Major maintenance such as cleaning an ion source,
cleaning the mass analyzer, replacing filament assemblies, or replacing the
GC column, etc., will require returning to the initial calibration step
(Sect. 10.2).
11. PROCEDURE
11.1. This section describes the procedures for sample preparation, SPE, final extract
preparation and storage, and extract analysis. Important aspects of this analytical
procedure include proper preparation of laboratory glassware, sample containers
(Sect. 4.1), and sample collection and storage (Sect. 8). Procedures for data analysis
and calculations are described in Sect. 12.
11.2. SAMPLE PREPARATION
11.2.1. Samples are preserved, collected and stored as described in Sect. 8. All field
and QC samples, including LRBs and LFBs, must contain the preservatives
listed in Sect. 8.1.2. Mark the level of the sample on the outside of the
sample bottle for later sample volume determination. If using weight to
determine volume (Sect. 11.6), weigh the bottle and sample contents before
extraction.
11.2.2. Add an aliquot of the SUR PDS(s) to each sample to be extracted. For full
scan method development work, a 10-jiL aliquot of each of the 500-|ig/mL
SUR PDSs (Sect. 7.2.2) was added to 1 L samples for a final concentration
of5.0|ig/L.
11.2.3. If the sample is an LFB, LFSM, or LFSMD, add the necessary amount of
Analyte Fortification Solution(s) (Sect. 7.2.3.2). Swirl each sample to
ensure all components are mixed.
11.2.4. Proceed with sample extraction using the SPE procedure described in Sect.
11.3.
11.3. CARTRIDGE SPE (6 mL) PROCEDURE - This cartridge extraction procedure may
be carried out in a manual mode or by using a robotic or automatic sample
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preparation device. This section describes the SPE procedure using the equipment
outlined in Sects. 6.9-6.11 in its simplest, least expensive mode without the use of a
robotic system. The manual mode described below was used to collect data presented
in Sect. 17. The extraction steps are written for an individual sample, but multiple
samples may be extracted simultaneously depending upon the extraction equipment
used.
11.3.1. CARTRIDGE CLEANUP - Install the SPE cartridge (Oasis HLB,
Phenomenex Strata-X, or Agilent Bond Elut Plexa as described in Sect.
6.9.1) into the vacuum manifold. For alternate sorbents, see Sect. 6
regarding sorbent equivalency. Wash the cartridge with 5 mL of DCM by
adding the solvent to the cartridge; draw about half through the sorbent,
soak for about one min, then draw the remaining solvent through the
cartridge.
11.3.2. CARTRIDGE CONDITIONING - Polymeric SPE sorbents are water
wettable (unlike C-18 SPE sorbents). Many manufacturers of polymeric
SPE media suggest that their products do not need to be kept wet during
conditioning and sample processing. However, little data have been shown
to demonstrate performance under those conditions for the wide variety of
environmental contaminants using these media. Therefore, in the interest of
providing a single procedure for the sorbents and analytes in this method,
the authors chose to use procedures similar to those used with C-18 where
the sorbent is kept wet.
11.3.2.1. CONDITIONING WITH METHANOL - Add 10 mLMeOHto
the cartridge and allow it to soak for about one min. Then draw
most of the MeOH through. A layer of MeOH must be left on the
surface of the cartridge. Do NOT let the cartridge go dry from this
point on until the end of sample extraction.
11.3.2.2. CONDITIONING WITH WATER - Rinse the cartridge by adding
10 mL of reagent water to the cartridge and drawing most through,
again leaving a layer on the surface of the cartridge.
11.3.3. SAMPLE EXTRACTION - Attach a PTFE transfer line to the top of the
cartridge. Insert the opposite end of the transfer line into the sample to be
extracted. Apply vacuum to begin the extraction. Adjust the vacuum so that
the sample passes through the cartridge at a rate of about 10 mL/min. Pass
the entire sample volume through the cartridge, draining as much water
from the sample container as possible. Rinse the bottle with 10 mL LRW
and transfer to the cartridge under full vacuum. Rinsing the sorbent with
LRW prior to drying helps remove sample preservatives from the sorbent so
they are not transferred to the extract. Remove the sample transfer line from
the cartridge and dry by maintaining vacuum for about 10 min.
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11.3.4. CARTRIDGE ELUTION - Remove the manifold lid (but do not remove the
cartridge) and insert a suitable collection tube to contain the eluent (15-mL
collection vial). Reassemble the apparatus. Add ~2 mL of acetone to the
sample bottle, and rinse the inside walls thoroughly. Allow the solvent to
settle to the bottom of the bottle, then transfer it to the cartridge. Draw the
solvent through the cartridge by applying vacuum. Add 5 mL of DCM to
the sample bottle, and rinse the inside walls thoroughly. Allow the solvent
to settle to the bottom of the bottle, and then transfer to the cartridge by
applying vacuum. Draw about half of the solvent through the cartridge, cut
off vacuum at the cartridge, and allow the cartridge to soak for one min.
Draw the remaining solvent through the cartridge. Repeat the above step
with another 5 mL of DCM. Shut off vacuum, remove the transfer line, and
remove the collection vial. Proceed to Sects. 11.4 and 11.5 to dry and
concentrate the extract.
11.4. DRYING THE EXTRACT - Transfer the combined eluent through a drying tube
containing about 7 g of anhydrous sodium sulfate. Rinse the collection tube with
3 mL DCM, and then put the DCM through the sodium sulfate. Collect the dried
extract and DCM rinse in a clean collection tube.
11.5. EXTRACT CONCENTRATION - Concentrate the extract to about 0.7 mL under a
gentle stream of nitrogen gas in a warm water bath (at ~ 40 °C). Do not blow down
samples to less than 0.5 mL, because the more volatile compounds will exhibit
diminished recovery. Transfer the extract to a 1-mL volumetric flask and add the
internal standards (Sect. 7.2.1). Rinse the collection tube that held the dried extract
with small amounts of DCM and add to the volumetric flask to bring the volume up
to the 1-mL mark. Transfer to an autosampler vial. Store extracts at -5 °C or less until
analysis.
11.6. SAMPLE VOLUME OR WEIGHT DETERMINATION - Use a graduated cylinder
to measure the volume of water required to fill the original sample bottle to the mark
made prior to extraction (Sect. 11.2.1). Determine volume to the nearest 10 mL for
use in the final calculations of analyte concentration (Sect. 12.2). If using weight to
determine volume, reweigh the empty sample bottle. Subtract the empty bottle
weight from the weight of the original combined bottle/sample weight measured in
Sect. 11.2.1. To calculate the sample volume from its weight, assume a sample
density of 1 g/mL. Use the calculated sample volume for analyte concentration
calculations in Sect. 12.2.
11.7. ANALYSIS OF SAMPLE EXTRACTS
11.7.1. Establish instrument operating conditions as described in Sect. 10.2.2.
Confirm that compound separation and resolution are similar to those
summarized in Table 1 and Figure 1.
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11.7.2. Establish a valid initial calibration following the procedures outlined in
Sect. 10.2 or confirm that the calibration is still valid by running a CCC as
described in Sect. 10.3. If establishing an initial calibration for the first
time, complete the IDC as described in Sect. 9.2.
11.7.3. Analyze aliquots of Field and QC Samples at appropriate frequencies
(Sect. 9) with the GC/MS conditions used to acquire the initial calibration
and the CCC. At the conclusion of data acquisition, use the same software
that was used in the calibration procedure to tentatively identify peaks in
predetermined retention time windows of interest. Use the data system
software to examine the ion abundances of components of the chromato-
gram to confirm identity.
12. DATA ANALYSIS AND CALCULATIONS
12.1. COMPOUND IDENTIFICATION - Identify sample components by comparison of
their retention times and mass spectra to the reference retention times and spectra in
the user-created data base as follows:
12.1.1. Establish an appropriate retention time window for each analyte, internal
standard and surrogate analyte to identify them in QC and Field Sample
chromatograms. Ideally, the retention time window should be based on
measurements of actual retention time variation for each compound in
standard solutions collected on each GC/MS over the course of time. The
suggested variation is plus or minus three times the standard deviation of
the retention time for each compound for a series of injections. The
injections from the initial calibration and from the IDC (Sect. 9.2) may be
used to calculate a suggested window size. However, the experience of the
analyst should weigh heavily on the determination of an appropriate
retention window size.
12.1.2. Each compound should be identified from its reference spectrum obtained
during the acquisition of the initial calibration curve. The mass spectrum
used for identification of each compound is acquired in the full scan or SIM
mode.
12.1.2.1. Full Scan MS Identification - In general, all ions that are present at
or above 30% relative abundance in the mass spectrum of the
reference standard obtained during calibration should be present in
the mass spectrum of the sample component and should agree
within an absolute 20%. For example, in full scan mode, if an ion
has a relative abundance of 30% in the standard spectrum, its
abundance in the sample spectrum should be in the range of
10-50%.
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12.1.2.2. SIM MS Identification - In SIM mode, all ions monitored in the
standard should be present in the SIM mass spectrum of the sample
component and relative abundance from integrated peak areas
should agree within absolute 20%. For example, if an ion has a
relative abundance of 30% in the standard spectrum, its abundance
in the sample spectrum should be in the range of 10-50%.
Secondary ions should have a relative abundance of >30% in the
standard The IS phenanthrene-30%, therefore no relative
abundance calculation for compound confirmation is required.
12.1.3. Identification is hampered when sample components are not resolved
chromatographically and produce mass spectra containing ions contributed
by more than one analyte. When GC peaks obviously represent more than
one sample component (i.e., broadened peak with shoulder(s) or valley
between two or more maxima), appropriate analyte spectra and background
spectra can be selected by examining plots of characteristic ions. Comparing
a background subtracted spectrum to the reference spectrum is suggested. If
two or more analytes coelute but only one GC peak is apparent, the
identification criteria can be met but each analyte spectrum will contain
extraneous ions contributed by the coeluting compound.
12.1.4. BHA exists as two structural isomers, 2-BHA and 3-BHA, which
commonly appear as one chromatographic peak. Structural isomers that
produce very similar mass spectra can be explicitly identified only if they
have sufficiently different GC retention times. Acceptable resolution is
achieved if the height of the valley between two isomer peaks is <25% of
the average height of the two isomer peaks. Otherwise, combine the peak
areas of the isomers and quantify and identify as an isomeric pair.
12.2. QUANTITATION AND CALCULATIONS
12.2.1. Calculate analyte and surrogate concentrations using the multipoint
calibration established in Sect. 10.2. In validating this method,
concentrations were calculated by measuring the characteristic ions listed in
Table 1. Other ions may be selected at the discretion of the analyst. Do not
use daily continuing calibration check data to quantitate analytes in
samples. Adjust the final analyte concentrations to reflect the actual sample
volume determined in Sect. 11.6. Field Sample extracts that require dilution
should be treated as described in Sect. 12.2.2.
12.2.2. If the calculated amount of any analyte exceeds the calibration range of the
curve, the extract must be diluted with DCM, with the appropriate amount
of additional internal standard added to match the original concentration.
Analyze the diluted extract. Acceptable surrogate performance (Sect. 9.3.6)
should be determined from the undiluted sample extract. Incorporate the
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dilution factor into final concentration calculations. The resulting sample
should be documented as a dilution, and MRLs should be adjusted
accordingly. If matrix-matched calibration standards are being used, the
dilution may be made with DCM, but care should be taken to dilute just
enough to position the analyte within the calibration range. Excessive
dilution and resulting low concentration may affect the accuracy of the final
measurement.
12.2.3. Calculations must utilize all available digits of precision, but final reported
concentrations should be rounded to an appropriate number of significant
figures (one digit of uncertainty), typically two, and not more than three
significant figures.
Note: Some data in Sect. 17 of this method are reported with more than two
significant figures. This is done to better illustrate the method performance
data.
13. METHOD PERFORMANCE
13.1. PRECISION AND ACCURACY DATA
13.1.1. FULL SCAN GC/MS - Precision and accuracy data were collected from
LFBs at three concentration levels using sorbents described in Sect. 6.9.1.
Precision and accuracy data were also collected at a single fortified
concentration using two challenging water matrices. Tap water matrices
were selected to be representative of ground water with high mineral
content and surface water with a moderate level of TOC. Precision and
accuracy data in both fortified reagent water and fortified matrices are
presented in Tables 3 and 4.
13.1.2. SIM GC/MS - The SIM GC/MS analysis option may be used for added
analyte sensitivity. Precision and accuracy data were collected using LFBs
fortified at three concentration levels. Precision and accuracy data were also
collected at a single fortified concentration using two challenging water
matrices. Tap water matrices were selected to be representative of ground
water with high mineral content and surface water with a moderate level of
TOC. Precision and accuracy data in both fortified reagent water and
fortified matrices are presented in Tables 7 and 8.
13.2. LCMRLsandDLs
13.2.1. FULL SCAN GC/MS - The DL and LCMRL values for all analytes in full
scan mode are presented in Table 5.
13.2.2. SIM GC/MS - The DL and LCMRL values for all analytes in SIM are
presented in Table 9.
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13.3. SAMPLE STORAGE STABILITY STUDIES - Drinking water samples from a
chlorinated surface source were used as a representative matrix for an analyte
holding time study in aqueous solution. Replicate samples in amber bottles were
preserved as described in Sect. 8, fortified with method analytes, then stored for
48 hours at 10 °C, followed by storage at 4 °C until analysis. Randomly selected
samples were analyzed in replicate (n=4) on day 0 and at several time points up to
the 14 day holding time. Data from days 0, 7 and 14 are presented in Fig. 2. These
data were used to establish the 14 day aqueous holding time for method analytes
(Sect. 8.4).
Notes:
• Surrogate analytes were not stored in this study, but added at the time of
extraction. The data in Fig. 2 for SURs are same day data, obtained for QC
purposes.
• Holding time studies conducted during method development indicated moderate
analyte losses (more than 10% in 14 days, with increasing loss at subsequent
time points) for o-toluidine using the sample collection, preservation and holding
time procedures in this method. o-Toluidine exhibited a loss of 11% at 7 days
and 14% at 14 days.
13.4. EXTRACT STORAGE STABILITY STUDIES - Replicate sample extracts (n=4)
that were stored at -5 °C and protected from light, were analyzed on days 0, 7 and 14.
Data from these analyses validate the 14 day extract holding time and are presented
in Fig. 3.
Notes:
• Surrogate analytes were stored in this study, added at the time of extraction.
• Extract holding time studies conducted during method development indicated
significant analyte losses (more than 15% in 14 days, with increasing loss at
subsequent time points) for o-toluidine using the sample collection, preservation
and holding time procedures in this method. o-Toluidine in extracts exhibited a
loss of 13% at 7 days and 16% at 14 days. The SUR o-toluidine-dg shows similar
losses in extracts overtime.
13.5. POTENTIAL PROBLEMS/ PROBLEM COMPOUNDS
13.5.1. MATRIX INDUCED CHROMATOGRAPHIC RESPONSE
ENHANCEMENT (MICRE) - BHA has the potential to exhibit a high bias.
The bias has been attributed to the phenomenon of MICRE. Examples of
this are shown in Table 8 for BHA, which show recovery data for fortified
tap waters that approach 130% of the fortified amount. Data in Table 4
show that this phenomenon is related to analyte concentration, since the
high bias is not observed at the higher fortified concentration. Although the
use of matrix-matched standards will improve quantitative accuracy for
BHA, a bias may still be observed. In addition to the use of matrix matched
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standards, "priming" the GC system by injecting one or more sample
extracts at the beginning of each analytical sequence was found to reduce
matrix enhancement effects. Literature citations suggest that temperature
programmed or cold injections may also reduce matrix enhancement,12'13'18
although trials of these types of injections during method development
showed little or no improvement. The biased data were instrument
dependent, and not related to the sorbent used. Similar tap water extracts
generated using different sorbent options listed in this method, showed
similarly high biased data on the same instrument.
Depending upon the intended use of the data, the analyst should consider
performing the MRL verification (Sect. 9.2.4.4) in fortified matrices similar
to the samples being analyzed.
13.5.2. OVERDRYING SPE MEDIA PRIOR TO ELUTION - If SPE media is
over dried between sample loading and solvent elution by drawing
excessive amounts of room air through the media, analytes that can undergo
oxidation may be observed to have low recoveries. An example of an
analyte that may be affected is o-toluidine.
13.6. MULTIPLE LABORATORY DEMONSTRATION - The performance of this
method was demonstrated by three independent laboratories. These laboratories
produced acceptable results and provided valuable method performance data. The
author wishes to acknowledge the assistance of the analysts and managers at the
laboratories listed below for their participation in the multi-laboratory study.
13.6.1. Dr. Yongtao Li and Mr. William Davis of Eurofins Eaton Analytical, Inc.,
South Bend, IN.
13.6.2. Mr. Kevin Durk and Ms. Annmarie Walsh of Suffolk County Water
Authority, Hauppauge, NY.
13.6.3. Dr. Andrew Eaton and Mr. Patrick Chapman of Eurofins Eaton Analytical,
Inc., Monrovia, CA.
14. POLLUTION PREVENTION
14.1. This method utilizes SPE to extract analytes from water. It requires the use of very
small volumes of organic solvent and very small quantities of pure analytes, thereby
minimizing the potential hazards to both the analyst and the environment as
compared to the use of large volumes of organic solvents in conventional liquid-
liquid extractions.
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14.2. For information about pollution prevention that may be applicable to laboratory
operations, consult "Less is Better: Guide to Minimizing Waste in Laboratories"
available on-line from the American Chemical Society at http://www.acs.org/content/
dam/acsorg/about/governance/committees/chemicalsafety/publications/less-is-
better.pdf
15. WASTE MANAGEMENT
15.1. The analytical procedures described in this method generate relatively small amounts
of waste since only small amounts of reagents and solvents are used. The matrices of
concern are finished drinking water or source water. However, the Agency requires
that laboratory waste management practices be conducted consistent with all
applicable rules and regulations, and that laboratories protect the air, water, and land
by minimizing and controlling all releases from fume hoods and bench operations.
Also, compliance is required with any sewage discharge permits and regulations,
particularly the hazardous waste identification rules and land disposal restrictions.
16. REFERENCES
1. Winslow, S.D., Pepich, B.V., Martin, J.J., Hallberg, G.R., Munch, D.J., Frebis, C.P.,
Hedrick, E. J., Krop, R. A., Statistical Procedures for Determination and Verification of
Minimum Reporting Levels for Drinking Water Methods, Environ. Sci. Technol, 2006, 40,
281-288.
2. Martin, J.J., Winslow, S.D., Munch, D. J., A New Approach to Drinking Water Quality Data:
Lowest Concentration Minimum Reporting Level, Environ. Sci. Technol., 2007, 41, 677-681.
3. Glaser, J.A., Foerst, D.L., McKee, G.D., Quave, S.A., Budde, W.L., Trace Analyses for
Wastewaters, Environ. Sci. Technol, 1981, 15, 1426-1435.
4. Erney, D.R., Gillespie, A.M., Gilvydis, D.M., Poole, C.F., Explanation of the Matrix-Induced
Chromatographic Response Enhancement of Organophosphorous Pesticides During Open
Tubular Column Gas Chromatography with Splitless or Hot On-Column Injection and Flame
Photometric Detection, J. Chromatogr., 1993, 638, 57-63.
5. Mol, H.G.J., Althuizen, M., Janssen, H, Cramers, C.A., Brinkman, U.A.Th., Environmental
Applications of Large Volume Injection in Capillary GC Using PTV Injectors, J. High Resol.
Chromatogr., 1996, 19, 69-79.
6. Erney, D.R., Pawlowski, T.M., Poole, C.F., Matrix Induced Peak Enhancement of Pesticides
in Gas Chromatography, J. High Resol. Chromatogr., 1997, 20, 375-378.
7. Hajslova, J., Holadova, K., Kocourek, V., Poustka, J., Godula, M., Cuhra, P., Kempny, M.,
Matrix Induced Effects: A Critical Point in the Gas Chromatographic Analysis of Pesticide
Residues, J. Chromatogr., 1998, 800, 283-295.
530-39
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8. Wylie, P., Uchiyama, M., Improved Gas Chromatographic Analysis of Organophosphorous
Pesticides with Pulsed Splitless Injection, J. AOAC International, 1996, 79, 571-577.
9. Hajslova, J., Zrostlikova, J., Matrix Effects in (Ultra) Trace Analysis of Pesticide Residues in
Food and Biotic Matrices, J. Chromatog. A, 2003, 1000,181-197.
10. Anastassiades, M., Mastovska, K., Lehotay, S.J., Evaluation of Analyte Protectants to
Improve Gas Chromatographic Analysis of Pesticides, J. Chromatog. A, 2003, 1015,163-184.
11. Poole, C.F., Matrix Induced Response Enhancement in Pesticide Residue Analysis by Gas
Chromatography, J. Chromatog. A, 2007, 1158, 241-250.
12. Thurman, E.M., Mills, M.S., Solid Phase Extraction Principles and Practice, John Wiley and
Sons, Inc., 1998, p. 66.
13. Prudent Practices in the Laboratory: Handling and Disposal of Chemicals, National
Academies Press (2011 updated version), ISBN: 9780309138642.
14. OSHA Safety and Health Standards, General Industry, (29CFR1910), Occupational Safety
and Health Administration, OSHA 2206, (Revised, July 2001).
15. Safety in Academic Chemistry Laboratories, American Chemical Society Publication,
Committee on Chemical Safety, 7th Edition. Available online at
http ://portal. acs.org/portal/PublicWeb Site/about/governance/committees/chemicalsafety/publ
ications/WPCP_012294 (accessed October 5, 2011).
16. Technical Notes on Drinking Water Methods, 1994, EPA Document #600/R-94/173.
Available through EPA's digital publications National Environmental Publications Internet
Site (NPEIS) database.
17. USEPA Office of Ground Water and Drinking Water, Technical Support Center, Alternate
Test Procedure Coordinator, 26 W. Martin Luther King Dr., Cincinnati, OH, 45268.
18. Szelewski, M., Environmental Semivolatiles Using an Agilent Multimode Inlet for
Maximum Sensitivity - Application Note. Agilent Technologies, Inc. 2850 Centerville Rd.,
Wilmington, DE 19809-1610.
19. Price, E.K., Prakash, B., Domino, M.M., Pepich, B.V., Munch, D.J., Method 527.
Determination of Selected Pesticides and Flame Retardants in Drinking Water by Solid Phase
Extraction and capillary Gas Chromatography/ Mass Spectrometry, 2005, EPA Document
#815-R-05-005. Available on-line at
http://www.epa.gov/ogwdw/methods/pdfs/methods/met527.pdf (accessed January 20, 2015).
530-40
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17. TABLES, FIGURES AND VALIDATION DATA
Table 1. Retention Times (RTs), Suggested Quantitation Ions (QIs), Suggested SIM
Secondary Ions, and Suggested Internal Standard Reference
Peak
Identification #,
Figure 1
5
7
1
2
3
4
6
8
RT
(min)
12.66
16.39
7.73
7.78
9.84
9.86
13.68
18.36
Internal Standards, Analytes and
Surrogates
acenaphthene-Jio (IS 1)
phenanthrene-Jio (IS 2)
o-toluidine-Jg (SUR)
o-toluidine
quinoline-t/7 (SUR)
quinoline
BHA
dimethipin
IS Ref. #
1
1
1
1
2
2
QI (m/z)
162
188
114
106
136
129
180
54
SIM
Secondary
Ion(s) (m/z)
164
__*
112
107
108
102
137
118
Comments
a
a
b
b
b
b
b, c
b
* No secondary ion present at >30% relative abundance.
Comment Key
a. PDS solvent, acetone
b. PDS solvent, methanol
c. Potential to exhibit matrix induced chromatographic response enhancement was observed during method
development. This assessment was done based on a peak area comparison of a standard prepared in solvent
compared to a matrix-matched standard, both at a concentration of 0.1 ng/uL. If the matrix-matched standard
area was >130% of the solvent prepared standard, the analyte was flagged as having the potential for matrix
induced chromatographic response enhancement.
530-41
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Table 2. Ion Abundance Criteria for Decafluorotriphenyl Phosphine (DFTPP)a
Mass (m/z)
68
69
70
197
198
199
365
441
442
443
Relative Abundance Criteria
<2%ofWz69
present
<2%ofWz69
<2% of m/z 198
present °
5-9% of m/z 198
>1% of base peak
<150%ofWz443
present °
15-24% of m/z 442
Purpose of Checkpoint15
Low-mass resolution
Low-mass resolution
Low-mass resolution
Mid-mass resolution
Mid-mass resolution and sensitivity
Mid-mass resolution and isotope ratio
Baseline threshold
High-mass resolution
High-mass resolution and sensitivity
High-mass resolution and isotope ratio
a. These ion abundance criteria have been developed specifically for target compound analysis
as described in this method. Adherence to these criteria may not produce spectra suitable for
identifying unknowns by searching commercial mass spectral libraries. If the analyst intends
to use data generated with this method to identify unknowns, adherence to stricter DFTPP
criteria as published in previous methods19 is recommended.
b. All ions are used primarily to check the mass accuracy of the mass spectrometer and data
system, and this is the most important part of the performance test. The three sets of
resolution checks, which include natural abundance isotope ratios, constitute the next most
important part of the performance test, followed by the correct setting of the baseline
threshold, as indicated by the presence of m/z 365.
c. Either m/z 198 or 442 is typically the base peak.
530-42
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Table 3. Precision and Accuracy Data Obtained for Method Analytes Extracted from
Fortified Reagent Water at Three Concentrations; Full Scan GC/MS Analyses
Analytes
o-toluidine-J9 (SUR)
o-toluidine
quinoline-t/7 (SUR)
quinoline
BHA
dimethipin
Fortified Cone.
0.10 ug/L*
n=4
Mean %
Recovery
87.2
101
103
123
110
91.5
RSD
1.7
24
0.70
16
13
9.2
Fortified Cone.
l.Oug/L*
n=4
Mean %
Recovery
90.8
94.2
104
112
104
105
RSD
1.9
2.9
3.9
2.7
2.8
5.1
Fortified Cone.
5.0 jig/L*
n=4
Mean %
Recovery
89.0
84.6
105
99.2
90.8
99.0
RSD
3.0
2.3
1.7
1.1
2.5
2.3
* Surrogate concentrations are 5.0 ug/L
Table 4. Precision and Accuracy Data Obtained for Method Analytes Extracted from
Fortified Finished Drinking Waters from Ground and Surface Water; n=4 for Each
Matrix; Full Scan GC/MS Analyses
Analytes
o-toluidine-d9 (SUR)
o-toluidine
quinoline-J? (SUR)
quinoline
BHA
dimethipin
Fortified
Cone. (jig/L)
1.0
1.0
1.0
1.0
1.0
1.0
Ground Water3
Mean %
Recovery0
87.0
86.0
98.5
97.6
99.2
106
RSD
1.7
2.2
1.4
1.2
7.5
3.7
Surface Waterb
Mean %
Recovery0
73.1
71.3
89.3
86.6
97.9
93.4
RSD
6.1
1.3
4.2
2.6
3.5
3.5
a. Tap water from a ground water source with high mineral content. Tap water hardness was 376 mg/L as calcium
carbonate.
b. Tap water from a surface water source. TOC of 2.0 mg/L.
c. Recoveries have been corrected to reflect the native amount in the unfortified matrix water.
530-43
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Table 5. DLs and LCMRLs (ug/L) Calculated from Replicate Analyses of Fortified Reagent
Water Samples Analyzed in Full Scan GC/MS Mode
Analytes
o-toluidine
quinoline
BHA
dimethipin
DL*
0.007
0.036
0.044
0.037
Fortified cone, of DL
replicates
0.05
0.05
0.05
0.05
LCMRL
0.011
0.084
0.062
0.075
* DL calculated from eight replicates.
Table 6. Example SIM Parameters for Method Analytes
SIM
Segment
#1
#2
#3
#4
#5
Compound
o-toluidine-Jg (SUR)
o-toluidine
quinoline-J? (SUR)
quinoline
acenaphthene-t/io (IS 1)
BHA
phenanthrene-Jio (IS 2)
dimethipin
RT
(min)
8.84
8.89
11.05
11.07
13.91
14.92
17.77
19.83
Qi
(m/z)
114
106
136
129
162
180
188
54
Secondary
Ion(s) (nt/z)
112
107
108
102
164
137
__*
118
Dwell
Time
(ms)
75
75
75
100
100
Scan Rate
(scan/sec)
3.1
3.1
3.1
8.3
4.5
* No secondary ion present at >30% relative abundance.
530-44
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Table 7. Precision and Accuracy Data Obtained for Method Analytes Extracted from
Fortified Reagent Water at Three Concentrations; SIM GC/MS Analyses
Analytes
o-toluidine-^9 (SUR)
o-toluidine
quinoline-J? (SUR)
quinoline
BHA
dimethipin
Fortified Cone.
0.01 jig/L*
n=4
Mean %
Recovery
88.9
98.8
107
112
137
121
RSD
3.2
22
1.8
2.5
11
15
Fortified Cone.
0.10 jig/L*
n=4
Mean %
Recovery
85.3
97.5
107
93.5
116
126
Mean %
Recovery
6.8
6.5
3.2
3.3
9.0
2.9
Fortified Cone.
0.50 jig/L*
n=4
Mean %
Recovery
91.4
101
102
105
112
116
RSD
9.4
8.4
4.3
5.3
8.9
1.2
* Surrogate concentrations are 0.50 ug/L.
Table 8. Precision and Accuracy Data Obtained for Method Analytes Extracted from
Fortified Finished Drinking Waters from Ground and Surface Water; n=4 for Each
Matrix; SIM GC/MS Analyses
Analytes
o-toluidine-^9 (SUR)
o-toluidine
quinoline-J? (SUR)
quinoline
BHA
dimethipin
Fortified
Cone. (jig/L)
0.10
0.10
0.10
0.10
0.10
0.10
Ground Water3
Mean %
Recovery0
90.4
87.7
103
108
124
106
RSD
3.4
2.1
3.0
2.9
2.6
2.4
Surface Waterb
Mean %
Recovery0
75.1
71.8
125
116
127
102
RSD
3.4
4.5
2.5
3.3
2.2
2.7
a. Tap water from a ground water source with high mineral content. Tap water hardness was 359 mg/L as calcium
carbonate.
b. Tap water from a surface water source. TOC of 5.7 mg/L.
530-45
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Table 9. DLs and LCMRLs (ug/L) Calculated from Replicate Analyses of Fortified Reagent
Water Samples Analyzed in SIM GC/MS Mode
Analytes
o-toluidine
quinoline
BHA
dimethipin
DL*
0.001
0.003
0.003
0.001
Fortified cone, of
DL replicates
0.005
0.005
0.005
0.005
LCMRL
0.003
0.005
0.013
0.003
* DL calculated from eight replicates.
530-46
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Table 10. Initial Demonstration of Capability (IDC) and Quality Control (QC) Requirements (Summary)
Method
Reference
Sect. 9.2.1
& 9.3.1
Sect. 9.2.2
Sect. 9.2.3
Sect. 9.2.4
Sect. 9.2.5
& 9.3.9
Requirement
Initial Demonstration of
Low Background
Initial Demonstration of
Precision (IDP)
Initial Demonstration of
Accuracy (IDA)
Minimum Reporting
Limit (MRL)
Confirmation
Calibration Confirmation,
Quality Control Sample
(QCS)
Specification and Frequency
Analyze LRB prior to any other IDC steps. When a new
lot of SPE media is obtained, verify that background is
at acceptable limits.
Analyze four to seven replicate LFBs fortified near the
midrange calibration concentration.
Calculate average recovery for replicates used in IDP.
Fortify, extract and analyze seven replicate LFBs at the
proposed MRL concentration. Calculate the mean,
standard deviation and HRpni for each analyte. Confirm
that the upper and lower limits for the Prediction
Interval of Result (Upper PIR, and Lower PIR, Sect.
9.2.4.2) meet the recovery criteria.
Analyze a standard from a second source (QCS) to
verify the initial calibration curve.
Acceptance Criteria
Demonstrate that the method analytes are < 1/3 the
MRL, and that possible interferences from
extraction media do not prevent the identification
and/or quantification of any analytes, SURs or ISs.
Note: This includes the absence of interferences at
both the QIs and secondary ions at the RTs of
interest.
%RSDmustbe<20%
Mean recovery + 30% of the true value for all
analytes except o-toluidine, which must be within
50-130% of the true value
Upper PIR < 150%
Lower PIR > 50%
± 30% of the expected value.
NOTE: Table 10 is intended as an abbreviated summary of QC requirements provided as a convenience to the method user. Because the information has been
abbreviated to fit the table format, there may be issues that need additional clarification, or areas where important additional information from the method text
is needed. In all cases, the full text of the QC in Sect. 9 supersedes any missing or conflicting information in this table.
530-47
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Table 11. Ongoing Quality Control (QC) Requirements (Summary)
Method
Reference
Requirement
Specification and Frequency
Acceptance Criteria
Sample Holding Time
14 days for analytes with appropriate preservation and
storage as described in Sects. 8.1-8.3.
Sample results are valid only if samples are
extracted within sample hold time.
Extract Holding Time
14 days stored at -5 °C and protected from light
Sample results are valid only if extracts are
analyzed within extract hold time.
Sect. 9.3.1
Laboratory Reagent Blank
(LRB)
One LRB with each extraction batch of up to 20 Field
Samples.
Demonstrate that the method analyte concentration
is < l/3 the MRL, and confirm that possible
interferences do not prevent quantification. If the
background concentration exceeds Vs the MRL,
results for the extraction batch are invalid.
Sect. 9.3.3
Laboratory Fortified
Blank (LFB)
One LFB is required for each extraction batch of up to
20 Field Samples. Rotate the fortified concentrations
between low, medium, and high amounts.
Results of LFB analyses at medium and high
fortifications must be ± 30% of the true value for all
analytes except o-toluidine which may be 50-130%
of the true value. Results of the low-level LFB must
be ± 50% of the true value.
Sect. 9.3.5
Internal Standard (IS)
Compare IS area to the mean IS area from the analysis
of each CAL in the initial calibration and the area in the
most recent CCC.
Peak area counts for all ISs in all injections must be
within ± 50% of their mean peak area calculated
during the initial calibration. Peak areas of ISs must
also be ± 30% from the most recent CCC. If the ISs
do not meet these criteria, target analyte results are
invalid. Consult Sect. 9.3.5 for further information.
Sect. 9.3.6
Surrogate (SUR)
Standards
The SUR standards are added to all calibration standards
and samples, including QC samples prior to extraction.
Calculate SUR recoveries.
Quinoline-^7 must be 70-130% of the true value and
o-toluidine-fife must be 50-130% of the true value. If
any SUR fails this criterion, report all results for
sample as suspect/SUR recovery.
Sect. 9.3.7
Laboratory Fortified
Sample Matrix (LFSM)
Analyze one LFSM per extraction batch (of up to 20
Field Samples) fortified with the method analytes at a
concentration greater than or equal to the native
concentration. Calculate LFSM recoveries.
See Sect. 9.3.7.3 for instructions on the
interpretation of LFSM results.
530-48
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Table 11. Ongoing Quality Control (QC) Requirements (Summary) (Continued)
Sect. 9.3.8
Laboratory Fortified
Sample Matrix Duplicate
(LFSMD) or Field
Duplicates (FD)
Extract and analyze at least one FD or LFSMD with
each extraction batch of up to 20 Field Samples. An
LFSMD may be substituted for a FD when the
frequency of detects for analytes of interest are low.
Calculate RPDs.
Method analyte RPDs for the LFSMD or FD should
be <30% at mid and high levels of fortification and
<50% at concentrations within two times the MRL.
Failure to meet this criterion may indicate a matrix
effect.
Sect. 9.3.9
Quality Control Sample
(QCS)
Analyze a QCS during the IDC, and each time new CAL
solutions or PDSs are prepared. A QCS must be
analyzed at least quarterly.
Results must be ±30% of the expected value.
Sect. 10.2
Initial Calibration
Use the IS calibration technique to generate a linear or
quadratic calibration curve for each analyte. A minimum
of six standards should be used for a calibration range of
two orders of magnitude. Suggested concentrations can
be found in Sect. 7.2.4. Check the calibration curve
against the acceptance criteria in Sect. 10.2.5.
When each calibration standard is calculated as an
unknown using the calibration curve, the result
should be ± 30% of the true value for all except the
lowest standard (
-------
Figure 1. Example full scan chromatogram of a calibration standard (concentration of 5 ng/uL injected for all analytes). Peak
identification numbers correspond to those in the legend and to those in Table 1.
kCounts-
400-
300-
200-
100-
0-
3,4
1. £>-toluidlne-rf9 (SUR)
2.o-toluidine
3. quinoline-d7 (SUR)
4. quinoline
5. acenaphthene-c/10 (IS 1)
6. BHA
7. phenanthrene-dlO (IS 2)
S. d'meth'p'n
I
7.5
10.0
12.5
minutes
15.0
17.5
530-50
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Figure 2. Results of Aqueous Holding Time Study (Sect. 13.3)
o-toluidine-d9 (SS) o-toluidine quinoline-d7 (SS)
quinoline
BHA
dimethipin
530-51
-------
Figure 3. Results of Extract Holding Time Study (Sect. 13.4)
u
£
n
01
E
o-toluidine-d9{SS) o-toluidine quinoline-d7 (SS)
quinoline
BHA
dimethipin
530-52
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