EPA Document # EPA 815-B-01-001
METHOD 317.0 DETERMINATION OF INORGANIC OXYHALIDE DISINFECTION
BY-PRODUCTS IN DRINKING WATER USING ION
CHROMATOGRAPHY WITH THE ADDITION OF A
POSTCOLUMN REAGENT FOR TRACE BROMATE ANALYSIS
Revision 2.0
July 2001
Herbert P. Wagner and Barry V. Pepich, IT Corporation and Daniel P. Hautman and
David J. Munch, US EPA, Office of Ground Water and Drinking Water
TECHNICAL SUPPORT CENTER
OFFICE OF GROUND WATER AND DRINKING WATER
U. S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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METHOD 317.0
DETERMINATION OF INORGANIC OXYHALIDE DISINFECTION BY-PRODUCTS
IN DRINKING WATER USING ION CHROMATOGRAPHY WITH THE ADDITION
OF A POSTCOLUMN REAGENT FOR TRACE BROMATE ANALYSIS
1. SCOPE AND APPLICATION
1.1 This method covers the determination of inorganic oxyhalide disinfection by-product
anions in reagent water, surface water, ground water, and finished drinking water. In
addition, bromide can be accurately determined in source or raw water and it has been
included due to its critical role as a disinfection by-product precursor. Bromide
concentration in finished water can differ significantly between preserved and
unpreserved samples and should not be attempted due to numerous variables which can
influence the concentration. Since this method, prior to the addition of the postcolumn
reagent (PCR), employs the same hardware as EPA Method 300.11, the analysis of the
common anions (using EPA Method 300.1, Part A1) can be performed using this
instrument setup with the postcolumn hardware attached but "off-line" and with the
appropriate smaller sample loop.
Inorganic Disinfection By-products by Conductivity Detection
Bromate (report values > 15.0 ug/L) Chlorite
Bromide (source or raw water only) Chlorate
Inorganic Disinfection By-product by Postcolumn UV/VIS Absorbance Detection
Bromate (report values > Minimum Reporting Limit (MRL) to 15.0 ug/L)
1.2 The single laboratory reagent water Method Detection Limits (MDL, defined in Section
3.14) for the above analytes are listed in Table 1. The MDL for a specific matrix may
differ from those listed, depending upon the nature of the sample and the specific
instrumentation employed.
1.2.1 In order to achieve comparable detection limits on the conductivity detector, an
ion chromatographic system must utilize suppressed conductivity detection, be
properly maintained and must be capable of yielding a baseline with no more
than 5 nanosiemen (nS) noise/drift per minute of monitored response over the
background conductivity.
1.2.2 In order to achieve acceptable detection limits on the postcolumn absorbance
detector, the postcolumn reagent must be delivered pneumatically and some
form of software signal filtering or smoothing of the absorbance signal from the
absorbance detector must be incorporated.2
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1.3 This method is recommended for use only by or under the supervision of analysts
experienced in the use of ion chromatography and in the interpretation of the resulting
ion chromatograms.
1.4 When this method is used to analyze unfamiliar samples for any of the above anions,
anion identification should be supported by the use of a fortified sample matrix
covering the anions of interest. The fortification procedure is described in Section
9.4.1.
1.5 Users of the method data should state the data quality objectives prior to analysis.
Users of the method must demonstrate the ability to generate acceptable results with
this method, using the procedures described in Section 9.0.
2. SUMMARY OF METHOD
2.1 A volume of sample, approximately 225 |_iL (see Note), is introduced into an ion
chromatograph (1C). The anions of interest are separated and measured, using a system
comprised of a guard column, analytical column, suppressor device, conductivity
detector, a postcolumn reagent delivery system (pneumatically controlled), a heated
postcolumn reaction coil, and a ultraviolet/visible (UVYVIS) absorbance detector.2'3
NOTE: A 225 uL sample loop can be made using approximately 111 cm (44 inches)
of 0.02 inch i.d. PEEK tubing. Larger injection loops may be employed.4
The volume should be verified to be within 5% by weighing the sample loop
empty, filling the loop with deionized water and re-weighing the loop
assuming the density of water is 1 mg/uL.
3. DEFINITIONS
3.1 ANALYSIS BATCH - A sequence of samples, which are analyzed within a 30 hour
period and include no more than 20 field samples. An analysis batch must also include
all required QC samples, which do not contribute to the maximum field sample total of
20. The required QC samples include:
• Laboratory Reagent Blank (LRB)
• Initial Calibration Check Standard (ICCS)
• Laboratory Fortified Blank (LFB)
• Continuing Calibration Check Standard (CCCS), when the batch contains more than
10 field samples
• End Calibration Check Standard (ECCS)
• Laboratory Fortified Matrix (LFM)
• Either a Field Duplicate (FD), a Laboratory Duplicate (LD) or a duplicate of the LFM
3.2 CALIBRATION STANDARD (CAL) - A solution prepared from the primary dilution
standard solution(s) or stock standard solutions and the surrogate analyte. The CAL
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solutions are used to calibrate the instrument response with respect to analyte
concentration.
3.3 INITIAL CALIBRATION STANDARDS - A series of CAL solutions (either
individual or combined target analytes) used to initially establish instrument calibration
and develop calibration curves for individual target anions (Section 10.2).
3.4 INITIAL CALIBRATION CHECK STANDARD (ICCS) - A CAL solution, (either
individual or combined target analytes) which is analyzed initially, prior to any field
sample analyses, which verifies previously established calibration curves. The
concentration for the initial calibration check standard MUST be at or below the MRL
(Section 3.15) level which is also the level of the lowest calibration standard (Section
10.3.1).
3.5 CONTINUING CALIBRATION CHECK STANDARDS (CCCS) - A CAL solution
(either individual or combined target analytes) which is analyzed after every tenth field
sample analyses which verifies the previously established calibration curves and
confirms accurate analyte quantitation for the previous ten field samples analyzed. The
concentration for the continuing calibration check standards should be either at a
middle calibration level or at the highest calibration level (Section 10.3.2).
3.6 END CALIBRATION CHECK STANDARD (ECCS) - A CAL solution (either
individual or combined target analytes) which is analyzed after the last field sample
analysis which verifies the previously established calibration curves and confirms
accurate analyte quantitation for all field samples analyzed since the last continuing
calibration check. The end calibration check standard should be either the middle or
high level continuing calibration check standard (Section 10.3.2).
3.7 FIELD DUPLICATES (FD) - Two separate field samples collected at the same time
and place under identical circumstances and handled exactly the same throughout field
and laboratory procedures. Analyses of field duplicates indicate the precision
associated with sample collection, preservation and storage, as well as with laboratory
procedures.
3.8 INSTRUMENT PERFORMANCE CHECK SOLUTION (PC) - A solution of one or
more method analytes, surrogates, or other test substances used to evaluate the
performance of the instrument system with respect to a defined set of criteria.
3.9 LABORATORY DUPLICATE (LD) - Two sample aliquots, taken in the laboratory
from a single field sample bottle, and analyzed separately with identical procedures.
Analysis of the initial sample (LJ and the duplicate sample [(Dc) Section 9.4.3.1]
indicate precision associated specifically with the laboratory procedures by removing
variation contributed from sample collection, preservation and storage procedures.
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3.10 LABORATORY FORTIFIED BLANK (LFB) - An aliquot of reagent water or other
blank matrix to which known quantities of the method analytes are added in the
laboratory. The LFB is 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.
3.11 LABORATORY FORTIFIED SAMPLE MATRIX (LFM) - An aliquot of an
environmental field sample to which known quantities of the method analytes are added
in the laboratory. The LFM is analyzed exactly like a sample, and its purpose is to
determine whether the field sample matrix contributes bias to the analytical result. The
background concentrations of the analytes in the field sample matrix must be
determined in a separate, unfortified aliquot and the measured values in the LFM
corrected for background concentrations.
3.12 LABORATORY REAGENT BLANK (LRB) - An aliquot of reagent water or other
blank matrix that is handled exactly as a sample including exposure to all glassware,
equipment, solvents, reagents, and surrogates that are used with other samples. The
LRB is used to determine if method analytes or other interferences are present in the
laboratory environment, the reagents, or the apparatus.
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 METHOD DETECTION LIMIT (MDL) - The minimum concentration of an analyte
that can be identified, measured and reported with 99% confidence that the analyte
concentration is greater than zero.5
3.15 MINIMUM REPORTING LEVEL (MRL) - The minimum concentration that can be
reported as a quantitated value for a target analyte in a sample following analysis. This
defined concentration can be no lower than the concentration of the lowest calibration
standard and can only be used if acceptable quality control criteria for the ICCS are met.
3.16 PROFICIENCY TESTING (PT) or PERFORMANCE EVALUATION (PE) SAMPLE
- A certified solution of method analytes whose concentration is unknown to the
analyst. Frequently, an aliquot of this solution is added to a known volume of reagent
water and analyzed with procedures used for samples. Often, results of these analyses
are used as part of a laboratory certification program to objectively determine the
capabilities of a laboratory to achieve high quality results.
3.17 QUALITY CONTROL SAMPLE (QCS) - A solution of method analytes of known
concentrations that is obtained from a source external to the laboratory and different
from the source of calibration standards. It is used to check laboratory performance
with externally prepared test materials.
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3.18 SURROGATE ANALYTE - An analyte added to all samples, standards, blanks, etc.,
which is unlikely to be found at a significant concentration, and which is added directly
in a known amount before any sample processing procedures are conducted (except in
the procedure for the removal of chlorite as described is Section 11.1.4). It is measured
with the same procedures used to measure other sample components. The purpose of
the surrogate analyte is to monitor method performance with each sample.
3.19 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.
4. INTERFERENCES
4.1 Interferences can be divided into three different categories: direct chromatographic
coelution, where an analyte response is observed at very nearly the same retention time
as the target anion; concentration dependant coelution, which is observed when the
response of higher than typical concentrations of the neighboring peak overlap into the
retention window of the target anion; and, ionic character displacement, where retention
times may significantly shift due to the influence of high ionic strength matrices (high
mineral content or hardness) overloading the exchange sites on the column and
significantly shortening target analyte's retention times.
4.1.1 A direct chromatographic coelution may be solved by changing columns, eluent
strength, modifying the eluent with organic solvents (if compatible with 1C
columns), changing the detection systems, or selective removal of the
interference with pretreatment. Sample dilution will have little to no effect.
The analyst must verify that these changes do not induce any negative affects on
method performance by repeating and passing all the QC criteria as described in
Section 9.
4.1.2 Sample dilution may resolve some of the difficulties if the interference is the
result of either concentration dependant coelution or ionic character
displacement, but it must be clarified that sample dilution will alter your
Minimum Reporting Limit (MRL) by a proportion equivalent to that of the
dilution. Therefore, careful consideration of project objectives should be given
prior to performing such a dilution. An alternative to sample dilution, may be
dilution of the eluent as outlined in Section 11.2.6.
4.1.3 Pretreatment cartridges can be effective as a means to eliminate certain matrix
interferences. With any proposed pretreatment, the analyst must verify that
target analyte(s) are not affected by monitoring recovery after pretreatment.
With advances in analytical separator column technology which employ higher
capacity anion exchange resins, the need for these cartridges has been greatly
reduced.
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4.2 Method interferences may be caused by contaminants in the reagent water, reagents,
glassware, and other sample processing apparatus that lead to discrete artifacts or
elevated baselines in an ion chromatogram. These interferences can lead to false
positive results for target analytes as well as reduced detection limits as a consequence
of elevated baseline noise.
4.3 Samples that contain particles larger than 0.45 microns and reagent solutions that
contain particles larger than 020 microns require filtration to prevent damage to
instrument columns and flow systems.
4.4 Close attention should be given to the potential for carry over peaks from one analysis
which will effect the proper detection of analytes of interest in a second or subsequent
analysis. Normally, in this analysis, the elution of sulfate (retention time of 17.5 min.)
indicates the end of a chromatographic run, but, in the ozonated and chlorine dioxide
matrices, which were included as part of the single operator accuracy and bias study, a
small response (200 nS baseline rise) was observed for a very late eluting unknown
peak following the response for sulfate. Consequently, a run time of 25 minutes is
recommended to allow for the proper elution of any potentially interferant late peaks. It
is the responsibility of the user to confirm that no late eluting peaks have carried over
into a subsequent analysis thereby compromising the integrity of the analytical results.
4.5 Any residual chlorine dioxide present in the sample will result in the formation of
additional chlorite prior to analysis. If residual chlorine dioxide is suspected in the
sample, the sample must be purged with an inert gas (helium, argon or nitrogen) for
approximately five minutes. This sparging must be conducted prior to ethylenediamine
preservation and at the time of sample collection.
4.6 The presence of chlorite can interfere with the quantitation of low concentrations of
bromate on the postcolumn UV/VIS absorbance detector. In order to accurately
quantify bromate concentrations in the range 0.5 - 15.0 |-ig/L in this postcolumn system,
the excess chlorite must be removed prior to analysis as outlined in Section 11.1.4.
5. SAFETY
5.1 The toxicity or carcinogenicity of each reagent used in this method have not been fully
established although the postcolumn reagent o-dianisidine, is listed as a potential
human carcinogen. Each chemical should be regarded as a potential health hazard and
exposure should be as low as reasonably achievable. Cautions are included for known
extremely hazardous materials or procedures.
5.2 Each laboratory is responsible for maintaining a current awareness file of Occupational
Safety and Health Administration (OSHA) regulations regarding the safe handling of
the chemicals specified in this method. A reference file of Material Safety Data Sheets
(MSDS) should be made available to all personnel involved in the chemical analysis.
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The preparation of a formal safety plan is also advisable. Additional references on
laboratory safety are available.6"9
5.3 The following chemicals have the potential to be highly toxic or hazardous, consult
MSDS.
5.3.1 Sulfuric acid - used to prepared a 25 mN sulfuric acid regenerant solution for
chemical suppression using a Dionex Anion Micro Membrane Suppressor
(AMMS) and for pretreatment for chlorite removal (Section 11.1.4)
5.3.2 Nitric acid - used to prepare the postcolumn reagent.
5.3.3 o-dianisidine [3, 3'- dimethoxybenzidine dihydrochloride (ODA)] - used as the
postcolumn reagent.
6. EQUIPMENT AND SUPPLIES
6.1 Ion chromatograph - Analytical system complete with ion chromatographic pump and
all required accessories including syringes, analytical columns, compressed gasses,
suppressor, conductivity detector, mixing "tee", postcolumn reagent delivery system,
reaction coil, reaction coil heater, UV/VIS absorbance detector (Figure 1) and a PC
based data acquisition and control system.
NOTE: Because of its acidic nature and high salt content, the PCR MUST be flushed
from the reaction coil upon completion of the final analysis and prevented from
draining through the reaction coil by gravity once the system is shut down. This can be
accomplished either manually or by incorporating a column switching valve in
combination with a flush and close method in the schedule.
6.1.1 Anion guard column - Dionex AG9-HC 4 mm (P/N 51791), or equivalent.
This column functions as a protector of the separator column. If omitted from
the system the retention times will be shorter.
6.1.2 Anion separator column - Dionex AS9-HC column, 4 mm (P/N 51786), or
equivalent (see Note). The AS9-HC, 4 mm column using the conditions outlined
in Table 1 produced the separations shown in Figures 2 and 3.
NOTE: The use of 2 mm columns is not recommended. A 50 uL sample loop
would be required with the 2 mm columns. This reduced injection volume
would decrease the "on-column" bromate and negatively affect PCR reactivity
and the subsequent absorbance response. As well, the 2 mm columns require a
flow rate approximately 4 times less than the 4 mm columns. At the lower flow
rates, band broading may become an issue and it would be difficult, if not
impossible, to accurately maintain the appropriate reduced flow rate for the
PCR.
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6.1.3 Anion suppressor device - The data presented in this method were generated
using a Dionex Anion Self Regenerating Suppressor (4 mm ASRS, P/N 46081).
An equivalent suppressor device may be utilized provided comparable
conductivity detection limits are achieved and adequate baseline stability is
attained as measured by a combined baseline drift/noise of no more than 5 nS
per minute over the background conductivity. The suppressor must be able to
withstand approximately 80 - 120 psi back pressure which results from
connecting the postcolumn hardware to the eluent out side of the suppressor.
6.1.3.1 The ASRS was set to perform electrolytic suppression at a current
setting of 100 mA using the external water mode. Insufficient baseline
stability was observed on the conductivity detector using the ASRS in
recycle mode.
6.1.3.2 This method was developed as a multiple component procedure
employing both suppressed conductivity and postcolumn UV/VIS
absorbance detectors in series. If a laboratory is exclusively interested
in monitoring trace bromate using the PCR and the UV/VIS
absorbance detector, the suppressor may not be required. The
performance data presented within this method for the PCR and
UV/VIS absorbance detector, is based upon a suppressed mobile phase
system. A laboratory must generate comparable data as a result of a
complete IDC (Section 9.2) in order to demonstrate comparability of a
non suppressed system.
6.1.4 Detector - Conductivity cell (Dionex CD20, or equivalent) capable of providing
data as required in Section 9.2.
6.1.5 Detector - Absorbance detector (Dionex AD20 or equivalent with 10 mm cell
pathlength, equipped with a tungsten source bulb, or equivalent and capable of
measuring absorbance at 450 nm) capable of providing data as required in
Section 9.2.
6.1.6 Postcolumn reagent delivery system (Dionex PC-10, or equivalent),
pneumatically delivers the postcolumn reagent to mixing tee. The pressure
settings will need to be established on an individual basis for each specific
instrument configuration and at a level which yields the prescribed PCR flow
rates.
6.1.7 Reaction Coil, 500 uL internal volume, knitted, potted or configured to fit
securely in the postcolumn reaction coil heater. (Dionex P/N 39349, or
equivalent).
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6.1.8 Postcolumn Reaction Coil Heater, capable of maintaining a temperature of up to
80°C. (Dionex PCH-2, or equivalent).
6.2 Data System - The Dionex Peaknet Data Chromatography Software was used to
generate all the data in the attached tables. Other computer based data systems may
achieve approximately the same MDLs but the user must demonstrate this by the
procedure outlined in Section 9.2.
6.3 Analytical balance - Used to accurately weigh target analyte salts for stock standard
preparation (±0.1 mg sensitivity).
6.4 Top loading balance - Used to accurately weigh reagents to prepare eluents (±10 mg
sensitivity).
6.5 Weigh boats - Plastic, disposable - for weighing eluent reagents.
6.6 Syringes - Plastic, disposable, 10 mL - used during sample preparation.
6.7 Pipets - Pasteur, plastic or glass, disposable, graduated, 5 mL and 10 mL.
6.8 Bottles - High density polyethylene (HOPE), opaque or glass, amber, 30 mL, 125 mL,
250 mL, used for sample collection and storage of calibration solutions. Opaque or
amber bottles are required due to the photoreactivity of the chlorite anion.
6.9 Micro beakers - Plastic, disposable - used during sample preparation.
6.10 Particulate filters - Gelman ion chromatography Acrodisc 0.45 micron (PN 4485)
syringe filters or equivalent. These cartridges are used to remove particulates and
[Fe(OH)3(s)] which is formed during the oxidation-reduction react ion between Fe (II)
and C1O2-.
6.11 Hydrogen cartridges - Dionex OnGuard-H cartridges (PN 039596) or equivalent.
These cartridges are conditioned according to the manufacturer's directions and are
used to protect the analytical column and the suppressor membrane by removing excess
ferrous iron [Fe (II)]. The ferrous iron is added to field samples to reduce chlorite
levels prior to analysis of chlorine dioxide disinfected water samples.
7. REAGENTS AND STANDARDS
7.1 Reagent water- Distilled or deionized water 18 M Q or better, free of the anions of
interest. Water should contain particles no larger than 0.20 microns.
7.2 Eluent solution - Sodium carbonate (CASRN 497-19-8) 9.0 mM. Dissolve 1.91 g
sodium carbonate (NajC^) in reagent water and dilute to 2 L.
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7.2.1 This eluent solution must be purged for 10 minutes with helium prior to use to
remove dissolved gases which may form micro bubbles in the 1C compromising
system performance and adversely effecting the integrity of the data.
Alternatively, an in-line degas apparatus maybe employed.
7.3 Stock standard solutions, 1000 mg/L (1 mg/mL) - Stock standard solutions maybe
purchased as certified solutions or prepared from ACS reagent grade, potassium or
sodium salts as listed below, for most analytes. Chlorite requires careful consideration
as outlined below in Section 7.3.4.1.
7.3.1 Bromide (Br) 1000 mg/L - Dissolve 0.1288 g sodium bromide (NaBr, CASRN
7647-15-6) in reagent water and dilute to 100 mL in a volumetric flask.
7.3.2 Bromate (BrO3~) 1000 mg/L - Dissolve 0.1180 g of sodium bromate (NaBrO3,
CASRN 7789-38-0) in reagent water and dilute to 100 mL in a volumetric flask.
7.3.3 Chlorate (C1CV) 1000 mg/L - Dissolve 0.1275 g of sodium chlorate (NaClO3,
CASRN 7775-09-9) in reagent water and dilute to 100 mL in a volumetric flask.
7.3.4 Chlorite (C1O2~) 1000 mg/L - If the amperometric titration of the technical
grade sodium chlorite (NaClO2), specified in 7.3.4.1, had indicated the purity of
the salt to be 80.0 % NaClO2, the analyst would dissolve 0.1676 g of sodium
chlorite (NaClO2, CASRN 7758-19-2) in reagent water and dilute to 100 mLin
a volumetric flask.
7.3.4.1 High purity sodium chlorite (NaCIO 2) is not currently commercially
available due to its potential explosive instability. Recrystallization of
the technical grade (approx. 80%) can be performed but it is labor
intensive and time consuming. The simplest approach is to determine
the exact purity of the NaCIO 2 using the iodometric titration
procedure.10 Following titration, an individual component standard of
chlorite must be analyzed to determine if there is any significant
contamination (greater than 1% of the chlorite weight) from chlorate,
bromate or bromide (as other method target anions) in the technical
grade chlorite standard.
NOTE: Stability of standards - Stock standards (Section 7.3) for most
anions are stable for at least 6 months when refrigerated at <6°C. The
chlorite standard is only stable for two weeks when stored refrigerated
at <6°C and protected from light. Dilute working standards should be
prepared monthly, except those that contain chlorite, which must be
prepared every two weeks or sooner if signs of degradation are
indicated by repeated QC failure.
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7.4 Ethylenediamine (EDA) preservation solution, 100 mg/mL - Dilute 2.8 mL of
ethylenediamine (99%) (CASRN 107-15-3) to 25 mL with reagent water. Prepare fresh
monthly.
7.5 Surrogate Solution, 0.50 mg/mL dichloroacetate (DCA) - Prepare by dissolving 0.065 g
dichloroacetic acid, potassium salt (C12CHCO2K, CASRN 19559-59-2) in reagent water
and diluting to 100 mL in a volumetric flask.
7.5.1 Dichloroacetate is potentially present in treated drinking waters as the acetate
of the organic disinfection by product, dichloroacetic acid (DCAA). Typical
concentrations of DCAA rarely exceed 50 |-ig/L, which, for this worst case
example, would represent only a five percent increase in the observed
response over the fortified concentration of 1.00 mg/L. Consequently, the
criteria for acceptable recovery (90% to 115%) for the surrogate is weighted to
115% to allow for this potential background.
7.5.2 Prepare this solution fresh every 3 months or sooner if signs of degradation are
indicated by the repeated failure of the surrogate QC criteria.
7.5.3 If the analyst is exclusively interested in monitoring trace bromate using the
PCR and the UV/VIS absorbance detector, the surrogate may be omitted since it
only yields a signal on the conductivity detector. If the surrogate is removed,
the laboratory must adhere to the alternate QC requirements found in Section
9.3.3.3 in order to monitor and demonstrate proper instrument performance.
7.6 Postcolumn reagent - The postcolumn reagent is prepared by adding 40 mL of 70%
redistilled nitric acid (purity as 99.999+%, Aldrich, Cat. No. 22,571-1, Milwaukee, WI,
or equivalent) to approximately 300 mL reagent water (see Note 1) in a well rinsed 500
mL volumetric flask (see Note 2) and adding 2.5 grams of ACS reagent grade KBr
(Sigma, Cat. No. P-5912, St. Louis, MO, or equivalent). Two-hundred-and-fifty
milligrams of purified grade o-dianisidine, dihydrochloride salt [(ODA), (Sigma, Cat.
No. D-3252, or equivalent)] are dissolved, with stirring, in 100 mL methanol
(Spectrophotometric grade, Sigma, Cat. No. M-3641, St. Louis MO, or equivalent).
After dissolution, the o-dianisidine solution is added to the nitric acid/KBr solution and
diluted to volume with reagent water. The reagent is stable for 24 hours and should be
prepared fresh daily prior to analysis.
7.6.1 The purity of all reagents employed in the preparation of the postcolumn reagent
is critical. Some commercial manufacturers/suppliers of laboratory chemicals
sell inferior grades of o-dianisidine dihydrochloride. ONLY the purified grade
of this reagent is acceptable (see Notes 3 and 4). The purified ODA
dihydrochloride salt is a white, fine powder.
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NOTE 1: For selected lots of ODA, the method sensitivity monitored by the
UV-vis detector may be increased by as much as 2-fold if the reagent water used
to prepare the ODA PCR is purged with helium for 30 minutes prior to
preparing the ODA solution.
NOTE 2: All glassware used to prepare the postcolumn reagent must be
thoroughly rinsed with reagent water prior to use. A champagne or light amber
coloration of the PCR reagent may be evident when freshly prepared. Over
several hours, this slight coloration will fade. Consequently, the PCR must be
prepared in advance and allowed to sit until it is clear, for a minimum of 4 hours
(preferably overnight) prior to use. Occasionally, no matter how well all the
glassware used to prepare the postcolumn reagent is rinsed, a darkly colored
solution (oxidized ODA) may result. These solutions MUST be discarded. For
this reason, it is recommended that the PCR be made in a series of 500 mL lots
with dedicated glassware. The clear solution should be filtered using a 0.45
micron membrane to remove particulates before use.
NOTE 3: Differences in purity as indicated by variations in the physical
appearance of different lots of ODA, even from the same manufacturer can
effect method sensitivity. Although considerably more expensive, a pelletized
form of ODA from one supplier (Sigma, Cat. No. D-9154, St. Louis, MO) has
shown to increase method sensitivity by as much as 2-fold over impure lots of
ODA. Care must be exercised when switching ODA lots to ensure the method
sensitivity is not compromised.
NOTE 4: The PCR reaction temperature was optimized at 60 °C with the
granular ODA that was available during the original method development.
Investigation of recent changes in physical appearance/decreased sensitivity and
stability of the ODA PCR indicated that, the method sensitivity with the ODA
currently available, can be dramatically increased (up to 180%) or increased by
up to a factor of 1.8) by increasing the reaction temperature to 80 °C. Use of
temperatures ranging from 60 to 80 °C may be used in this method.
7.7 Ferrous iron [1000 mg/L Fe (II)] solution - Dissolve 0.124 g ferrous sulfate
heptahydrate (FeSO4.7H2O, Sigma, F-7002) in approximately 15 mL reagent water
containing 6 uL concentrated nitric acid and dilute to 25 mL with reagent water in a
volumetric flask (final pH ~2). The Fe (II) solution must be prepared fresh every two
days.
7.8 Sulfuric acid (0.5 N) - Dilute 1.4 mL of concentrated sulfuric acid (Fisher Scientific
Certified ACS Plus, A 3 00-500) to 100 mL.
8. SAMPLE COLLECTION, PRESERVATION AND STORAGE
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8.1 Samples should be collected in plastic or glass bottles. All bottles must be thoroughly
cleaned and rinsed with reagent water. The volume collected should be sufficient to
insure a representative sample, allow for replicate analysis and laboratory fortified
matrix analysis, if required, and minimize waste disposal.
8.2 Special sampling requirements and precautions for chlorite.
8.2.1 Sample bottles used for chlorite analysis must be opaque or amber to protect the
sample from light
8.2.2 When preparing the LFM, be aware that chlorite is an oxidant and may react
with the natural organic matter in an untreated drinking water mafrix as a result
of oxidative demand. If untreated water is collected for chlorite analysis, and
subsequently used for the LFM, EDA preservation will not control this demand
and reduced chlorite recoveries may be observed.
8.3 Sample preservation and holding times for the anions are as follows:
Analvte Preservation Holding Time
Bromate 50 mg/L EDA, refrigerate at <6°C 28 days
Chlorate 50 mg/L EDA, refrigerate at <6°C 28 days
Chlorite 50 mg/L EDA, refrigerate at <6°C 14 days
Bromide (source/raw water only) EDA permitted, refrigerate at <6°C 28 days
NOTE: Samples for chlorite analysis must arrive at the laboratory within 48 hours of
collection and must be received at 10°C or less.
8.4 When collecting a field sample from a treatment plant employing chlorine dioxide, the
field sample must be sparged with an inert gas (helium, argon, nitrogen) prior to
addition of the EDA preservative at time of sample collection.
8.5 All four anions (bromate > 15.0 ug/L) can be analyzed by conductivity, in a sample
matrix which has been preserved with EDA. Add a sufficient volume of the EDA
preservation solution (Section 7.4) such that the final concentration is 50 mg/L in the
sample. This would be equivalent to adding 0.5 mL of the EDA preservation solution
to 1 L of sample.
8.6 Chlorite is susceptible to degradation both through catalytic reactions with dissolved
iron salts and reactivity towards free chlorine which exists as hypochlorous
acid/hypochlorite ion in most drinking water as a residual disinfectant.11 EDA serves a
dual purpose as a preservative for chlorite by chelating iron as well as any other
catalytically destructive metal cations and removing hypochlorous acid/hypochlorite ion
by forming an organochloramine. EDA preservation of chlorite also preserves the
integrity of chlorate which can increase in unpreserved samples as a result of chlorite
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degradation. EDA also preserves the integrity of bromate concentrations by binding
with hypobromous acid/hypobromite ion which is an intermediate formed as a by-
product of the reaction of either ozone or hypochlorous acid/hypochlorite ion with
bromide ion. If hypobromous acid/hypobromite ion is not removed from the matrix,
further reactions may form bromate ion.
9. QUALITY CONTROL
9.1 Each laboratory using this method is required to operate a formal quality control (QC)
program. The requirements of this program consist of an initial demonstration of
laboratory capability (IDC), and subsequent analysis in each analysis batch (Section
3.1) of a Laboratory Reagent Blank (LRB), Initial Calibration Check Standard (ICCS),
Laboratory Fortified Blank (LFB), Instrument Performance Check Standard (IPC),
Continuing Calibration Check Standards (CCCS), Laboratory Fortified Sample Matrix
(LFM) and either a Field, Laboratory or LFM duplicate sample analysis. This section
details the specific requirements for each of these QC parameters for both the
conductivity and absorbance detectors used in this application. Although this method
involves both conductivity and absorbance detection, the MDLs and MRLs may differ
but the QC requirements and acceptance criteria are the same for both detectors. The
QC criteria discussed in the following sections are summarized in Section 17, Tables 4
and 5. The laboratory is required to maintain performance records that define the
quality of the data that are generated.
9.2 INITIAL DEMONSTRATION OF CAPABILITY
9.2.1 The Initial Demonstration of Capability (IDC) - This is used to characterize
instrument and laboratory performance prior to performing analyses by this
method. The QC requirements for the IDC discussed in the following section
are summarized in Section 17, Table 4.
9.2.2 Initial demonstration of low system background - Section 9.3.1.
9.2.3 Initial Demonstration of Precision (IDP) - For the 4 conductivity detector
analytes, prepare 7 replicate LFBs fortified at a recommended concentration of
20 ug/L. For the absorbance detector, prepare 7 replicate LFBs fortified at a
recommended concentration of 2.0 ug/L bromate. The percent relative standard
deviation (RSD) of the results must be less than 20%.
9.2.4 Initial Demonstration of Accuracy (IDA) - Using the data generated for Section
9.2.3, calculate the average recovery. The average recovery of the replicate
values must be within ± 15% of the true value.
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9.2.5 Quality Control Sample (QCS) - After calibration curves have initially been
established or have been re-established, on a quarterly basis or as required to
meet data quality needs, verify both the calibration and acceptable instrument
performance with the preparation and analyses of an external/second source
QCS. If the determined concentrations are not within ± 20% of the stated
values, performance of the method is unacceptable. The source of the problem
must be identified and corrected before proceeding with the IDC.
9.2.6 Method Detection Limit (MDL) - MDLs must be established for all analytes,
using reagent water (blank) fortified at a concentration of three to five times the
estimated instrument detection limit.4 To determine MDL values, take seven
replicate aliquots of the fortified reagent water and process through the entire
analytical method. The replicates must be prepared and analyzed over three
days. Report the concentration values in the appropriate units. Calculate the
MDL as follows:
MDL = (t) x (S)
where, t = student's t value for a 99% confidence level and a standard
deviation estimate with n-1 degrees of freedom
[t = 3.14 for seven replicates], and
S = standard deviation of the replicate analyses.
9.2.6.1 MDLs should be periodically verified, but MUST be initially
determined when a new operator begins work or whenever there is a
significant change in the background, or instrument response.
NOTE: Do not subtract blank values when performing MDL
calculations.
9.2.7 Minimum Reporting Level (MRL) - The MRL is the threshold concentration of
an analyte that a laboratory can expect to accurately quantitate in an unknown
sample. The MRL should be established at an analyte concentration either
greater than three times the MDL or at a concentration which would yield a
response greater than a signal to noise ratio of five. Setting the MRL too low
may cause repeated QC failure upon analysis of the ICCS. Although the lowest
calibration standard may be below the MRL, the MRL must never be
established at a concentration lower than the lowest calibration standard.
9.3 ASSESSING LABORATORY PERFORMANCE
9.3.1 Laboratory Reagent Blank (LRB) - The laboratory must analyze at least one
LRB with each analysis batch (Section 3.1). Data produced are used to assess
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contamination from the laboratory environment. Values that exceed Vz the MRL
indicate a laboratory or reagent contamination is present. If a method analyte is
observed in the LRB it must not exceed Vz the MRL. Analytes that exceed this
level will invalidate the analysis batch for that method analyte in all
corresponding field samples.
9.3.1.1 EDA must be added to the LRB at 50 mg/L. By including EDA in the
LRB, any bias as a consequence of the EDA which may be observed in
the field samples, particularly in terms of background contamination,
will be identified.
9.3.1.2 When the PCR method is used for low level bromate analysis on
samples from public water systems (PWSs) which employ chlorine
dioxide disinfection, the matrix must be pretreated to remove the
potentially interferant chlorite anion (Section 11.1.4). When these
types of pretreated samples, or any type of pretreatment is applied to
field samples included as part of an analysis batch, a second LRB must
be prepared, pretreated and analyzed to confirm no background effects
of the pretreatenent are present. If the analysis batch contains only
pretreated samples, then only a pretreated LRB is required.
9.3.2 Laboratory Fortified Blank (LFB) - Prepare a secondary dilution stock using the
same stock solutions used to prepare the calibration standards and the LFM
fortification solution. Since calibration solutions are prepared in large volumes
and can be used over an extended period of time, the integrity of the
concentration of the solution used to fortify the LFM is checked by analyzing
the LFB. The recovery of all analytes must fall in the acceptable recovery range,
as indicated below, prior to analyzing samples. If the LRB recovery for an
analysis batch does not meet these recovery criteria the data are considered
invalid, and the source of the problem must be identified and resolved before
continuing with analyses.
LFB Fortified Concentration range LFB Percent Recovery Limits
MRL to 5 x MRL 75 - 125 %
5 x MRL to highest calibration level 85 - 115 %
9.3.2.1 EDA must be added to the LFB at 50 mg/L. The addition of EDA to
all reagent water prepared calibration and quality control samples is
required not as a preservative but rather as a means to normalize any
bias attributed by the presence of EDA in the field samples.
9.3.3 Instrument Performance Check (IPC) - The Initial Calibration Check Standard
(ICCS) is to be evaluated as the IPC solution in order to confirm proper
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instrument performance. As specified in Section 10.3.1, this must be done using
the lowest calibration standard or the standard level established as the MRL.
This analysis confirms the MRL and demonstrates proper chromatographic
performance at the beginning of each analysis batch. Chromatographic
performance is judged by calculating the Peak Gaussian Factor (PGF), which is
a means to measure peak symmetry and monitoring retention time drift in the
surrogate peak over time. If these criteria are not met, corrective action must be
performed prior to analyzing additional samples. Major maintenance like
replacing columns require rerunning the IDC (Section 9.2).
9.3.3. 1 Critically evaluate the surrogate peak in the initial calibration check
standard, and calculate the PGF as follows:
1.83 x WO/2)
PGF = -----------------------
W(V10)
where, W(1A) is the peak width at half height, and
W (V10) is the peak width at tenth height.
NOTE: Values for W(x/2) and W (V10) can be attained through most
data acquisition software.
9.3.3.2 Small variations in retention time can be anticipated when a new
solution of eluent is prepared but if sudden shifts of more than 5% are
observed in the surrogate retention time, some type of instrument
problem is present. Potential problems include improperly prepared
eluent, erroneous method parameters programmed such as flow rate or
some other system problem. The chromatographic profile (elution
order) of the target anions following an ion chromatographic analysis
should closely replicate the profile displayed in the test chromatogram
that was shipped when the column was purchased. As a column ages, it
is normal to see a gradual shift and shortening of retention times, but if
after several years of use, extensive use over less than a year, or use
with harsh samples, this retention time has noticeably shifted to any
less than 80% of the original recorded value, the column requires
cleaning or replacement; especially if resolution problems are
beginning to become common between previously resolved peaks. A
laboratory should retain a historic record of retention times for the
surrogate and all the target anions to provide evidence of an analytical
columns vitality.
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9.3.3.3 If a laboratory chooses to monitor exclusively for trace bromate using
PCR and the UV/VIS absorbance detector, and no other analytes are
being monitored on the conductivity detector, the surrogate maybe
omitted from the procedure. In this case, no measurement of PGF is
required. However, the laboratory must carefully monitor the bromate
retention time in the ICCS as an alternate to the surrogate retention
time and, in the same manner, adhere to those specifications set forth
in Section 9.3.3.2. During the course of the analysis, bromate retention
times in the CCCS and ECCS must also be closely monitored to be
certain they adhere to the QC requirements set forth in Section
10.3.2.2.
9.4 ASSESSING ANALYTE RECOVERY AND DATA QUALITY
9.4.1 Laboratory Fortified Sample Matrix (LFM) - The laboratory must add a known
amount of each target analyte to a minimum of 5% of the collected field samples
or at least one with every analysis batch, whichever is greater. Additional LFM
requirements, as described in Section 9.4.1.5, apply when the PCR system is
used for low level bromate in chlorine dioxide disinfected waters. For a LFM to
be valid, the target analyte concentrations must be greater than the native level
and must adhere to the requirement outlined in Section 9.4.1.2. It is
recommended that the solutions used to fortify the LFM be prepared from the
same stocks used to prepare the calibration standards and not from external
source stocks. This will remove the bias contributed by an externally prepared
stock and focus on any potential bias introduced by the field sample matrix.
9.4.1.1 The fortified concentration must be equal to or greater than the native
concentration. Fortified samples that exceed the calibration range
must be diluted to be within the linear range. In the event that the
fortified level is less than the observed native level of the unfortified
matrix, the recovery should not be calculated. This is due to the
difficulty in calculating accurate recoveries of the fortified
concentration when the native sample concentration to fortified
concentration ratio is greater than one.
9.4.1.2 The LFM should be prepared at concentrations no greater than ten
times the highest concentration observed in any field sample and
should be varied to reflect the range of concentrations observed infield
samples. If no analytes are observed in any field sample, the LFM
should be fortified near the MRL.
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9.4.1.3 Calculate the percent recovery for each target analyte, corrected for
concentrations measured in the unfortified sample. Percent recovery
should be calculated using the following equation:
(C. - C)
%REC = x 100
where, %REC = percent recovery,
Cs = fortified sample concentration,
C = native sample concentration, and
s = concentration equivalent of analyte added to sample.
9.4.1.4 Recoveries may exhibit a matrix dependence. If the recovery of any
analyte falls outside 75 - 125%, and the laboratory's performance for
all other QC performance criteria are acceptable, the accuracy problem
encountered with the fortified sample is judged to be matrix related,
not system related. The result for that analyte in the unfortified sample
and the LFM must be labeled suspect/matrix to inform the data user
that the result is suspect due to matrix effects. Repeated failure to
meet suggested recovery criteria indicates potential problems with the
procedure and should be investigated.
9.4.1.5 When the PCR method is used for low level bromate analysis on field
samples from PWSs which employ chlorine dioxide disinfection and
consequently contain chlorite, a LFM must be prepared, exclusively
for trace bromate, for each of these field samples. Initially, the field
sample is analyzed and chlorite, chlorate and bromide levels are
determined. Then, a second aliquot of field sample ispretreated to
remove chlorite, as described in Section 11.1.4, and analyzed to
determine native bromate concentration. A third aliquot of the field
sample then must be fortified with bromate, pretreated as described in
Section 11.1.4 to remove chlorite, and analyzed to assess bromate
recovery from that matrix. This additional QC is required to rule out
matrix effects and to confirm that the laboratory performed the chlorite
removal step (Section 11.1.4.1) appropriately. This LFM should be
fortified with bromate at concentrations close to but greater than the
level determined in the native sample. Recoveries are determined as
described above (Section 9.4.1.3). Samples that fail the LFM percent
recovery criteria of 75 -125% must be reported as suspect/matrix.
9.4.2 SURROGATE RECOVERY- The surrogate is specific to the conductivity
detector and shows no response on the postcolumn absorbance detector.
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Calculate the surrogate recovery for the conductivity detector from all analyses
using the following formula:
SRC
%REC = xlOO
SFC
where, %REC = percent recovery,
SRC = surrogate recovered concentration, and
SFC = surrogate fortified concentration.
9.4.2.1 Surrogate recoveries must fall between 90-115% for proper instrument
performance and analyst technique to be verified. The recovery range
for the surrogate is extended to 115% to allow for the potential
contribution of trace levels of dichloroacetate as a halogenated organic
disinfection by-product (DBF) of dichloroacetic acid (DCAA).
Background levels of this organic DBF are rarely observed above 50
l-ig/L (0.05 mg/L) which constitutes only 5% of the 1.00 mg/L
recommended fortified concentration.
9.4.2.2 If the surrogate recovery falls outside the 90-115% recovery window,
an analysis error is evident and sample reanalysis is required. Poor
recoveries could be the result of imprecise sample injection or analyst
fortification errors. If the second analysis also fails the recovery
criterion, report all data for that sample as suspect.
9.4.2.3 If a laboratory chooses to monitor exclusively for trace bromate using
PCR and the UV/VIS absorbance detector, and no other analytes are
being monitored on the conductivity detector, the surrogate maybe
omitted from the procedure. In this situation, the laboratory MUST
adopt the QC protocol outlined in Section 9.3.3.3.
9.4.3 FIELD OR LABORATORY DUPLICATES - The laboratory must analyze
either a field or a laboratory duplicate for a minimum of 5% of the collected
field samples or at least one with every analysis batch, whichever is greater.
The sample matrix selected for this duplicate analysis must contain measurable
concentrations of the target anions in order to establish the precision of the
analysis set and insure the quality of the data. If none of the samples within an
analysis batch have measurable concentrations, the LFM should be repeated as a
laboratory duplicate.
9.4.3.1 Calculate the relative percent difference (RPD) from the mean using
the following formula:
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RPD = xlOO
(Pc + Dc]/2)
where, RPD = relative percent difference
Ic = the initial quantitated concentration, and
Dc = the duplicate quantitated concentration
9.4.3.2 Duplicate analysis acceptance criteria.
Concentration range RPD Limits
MRL to 5 x MRL ± 20 %
5 x MRL to highest calibration level ± 10 %
9.4.3.3 If the RPD for any target analyte falls outside the acceptance criteria
(Section 9.4.3.2) and if all other QC performance criteria are met for
that analyte, the result for the sample and duplicate should be labeled
as suspect/matrix to inform the data user that the result is suspect due
to a potential matrix effect, which led to poor precision This should
not be a chronic problem and if it frequently recurs (>20% of duplicate
analyses), it indicates a problem with the instrument or analyst
technique that must be corrected.
9.4.4 In recognition of the rapid advances occurring in chromatography, the analyst is
permitted certain options, such as the use of different columns, injection
volumes, and/or eluents, to improve the separations or lower the cost of
measurements. Each time such modifications to the method are made, the
analyst is required to repeat the procedure in Section 9.2 and adhere to the
condition of conductivity baseline stability found in Section 1.2.1.
9.4.5 It is recommended that the laboratory adopt additional quality assurance (QA)
practices for use with this method. The specific practices that are most
productive depend upon the needs of the laboratory and the nature of the
samples. Whenever possible, the laboratory should perform analysis of quality
control check standards and participate in relevant proficiency testing (PT) or
performance evaluation (PE) sample studies.
10. CALIBRATION AND STANDARDIZATION
10.1 Demonstration and documentation of acceptable initial calibration is required prior to
the IDC and before any samples are analyzed, is required intermittently throughout
sample analysis to meet required QC performance criteria outlined in this method and is
summarized in Tables 4 and 5. Initial calibration verification is performed using a QCS
as well as with each analysis batch using an initial, continuing (when more than 10 field
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samples are analyzed), and end calibration standards. The procedures for establishing
the initial calibration curve are described in Section 10.2. The procedures to verify the
calibration with each analysis batch is described in Section 10.3.
10.2 INITIAL CALIBRATION CURVE
10.2.1 Establish ion chromatographic operating parameters equivalent to those
indicated in Table 1 and configured as shown in Figure 1.
10.2.2 Estimate the Linear Calibration Range - The linear concentration range is the
concentration range over which the instrument response is linear. On the
conductivity detector for the four target analytes (chlorite, bromate, bromide and
chlorate) the linear range should cover the expected concentration range of the
field samples and should not extend over more than two orders of magnitude in
concentration. The restriction of two orders of magnitude is prescribed since
beyond this it is difficult to maintain linearity throughout the entire calibration
range.
10.2.2.1 If quantification is desired over a larger range, then two separate
calibration curves must be prepared.
10.2.2.2 For an individual calibration curve, a minimum of three calibration
standards are required for a curve that extends over a single order of
magnitude and a minimum of five calibration standards are required if
the curve covers two orders of magnitude. Because high
concentrations of chlorite can interfere with the postcolumn analysis of
low levels of bromate, the conductivity and absorbance detectors must
be calibrated separately.
10.2.2.3 Since the concentration ranges in actual field samples by conductivity
detection for chlorite, bromide and chlorate are expected to cover two
orders of magnitude, the use of at least five calibration standards in the
range 5 - 500 |-ig/L is recommended. Bromate concentrations are
expected to be significantly lower. It is suggested that the conductivity
detector be calibrated using at least five bromate calibration standard
levels in the range 5-100 |-ig/L. Additionally, report values for
bromate by conductivity ONLY when they are measured by the PCR
above 15.0 ug/L. The conductivity detector will observe a response for
bromate at concentration below 15.0 ug/L but concentrations between
5.0 and 15.0 ug/L are within the calibrated range for PCR detection
and will reflect far better precision and accuracy.
10.2.2.4 Although the bromate calibration curve for the absorbance detector
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extends over less than two orders of magnitude, the use of five
calibration standards, containing only bromate in the range 0.5-15.0
l-ig/L, is recommended.
10.2.3 Prepare the calibration standards by carefully adding measured volumes of one
or more stock standards (Section 7.3) to a volumetric flask and diluting to
volume with reagent water. Prior to using mixed standards for calibration, it
must be ensured that the individual calibration standards do not contain any
appreciable concentrations of the other target analytes.
10.2.3.1 EDA must be added to the calibration standards at 50 mg/L. The
addition of EDA to all reagent water prepared calibration and quality
control samples is required not as a preservative but rather as a means
to normalize any bias contributed by the addition of EDA to preserve
the field samples.
10.2.3.2 Prepare a 10.0 mL aliquot of surrogate fortified calibration solution
which can be held for direct manual injection or used to fill an
autosampler vial. This is done by adding 20 |_iL of the surrogate
solution (Section 7.5) to a 20 mL disposable plastic micro beaker.
Next, transfer 10.0 mL of calibration standard into the micro beaker
and mix. These volumes may be adjusted to meet specific laboratory
autosampler volume requirements provided the fortified surrogate
concentration is at the prescribed concentration of 1.0 mg/L. The
calibration standard is now ready for analysis. The same surrogate
solution that has been employed for the standards should also be used
in Section 11.1 for the field samples.
NOTE: This surrogate fortification procedure may be omitted if a
laboratory chooses to monitor exclusively for trace bromate using PCR
and the UV/VIS absorbance detector, and no other analytes are being
monitored on the conductivity detector. In this situation, the
laboratory must adopt the QC protocol outlined in Section 9.3.3.3.
10.2.4 Inject 225 |_iL of each calibration standard. Increased sensitivity for low level
detection of bromate by PCR can be achieved by increasing the injected sample
volume.4 If the injection volume is increased special operating conditions must
be used to insure proper chromatographic performance.4
10.2.5 Tabulate peak area responses against the concentration for the four target
analytes, the surrogate from the conductivity detector and bromate from the
postcolumn absorbance detector. The results are used to prepare calibration
curves using linear regression analysis for each analyte on the conductivity
detector and using a quadratic regression analysis for bromate on the absorbance
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detector.
10.2.5.1 Use of peak areas are strongly recommended since they have been
found to be more consistent, in terms of quantitation, than peak
heights. Peak height can tend to be suppressed as a result of high
levels of common anions in a given matrix which can compete for
exchange sites leading to peak broadening. Using peak areas, it is the
analyst responsibility to review all chromatograms to insure accurate
baseline integration of target analyte peaks, since poorly drawn
baselines will more significantly influence peak areas than peak
heights.
10.2.6 After establishing or reestablishing calibration curves, the accuracy of this
calibration must be verified through the analysis of a QCS or an externally
prepared second source standard. The QCS should be prepared at a
concentration near the middle of the calibration and is best to be analyzed in
triplicate. As specified in Section 9.2.5, determined concentrations must fall
within ±15% of the stated values.
10.3 CONTINUING CALIBRATION VERIFICATION - Initial calibrations maybe stable
for extended periods of time. Once the calibration curves have been established for
both the conductivity and absorbance detectors, they must be verified for each analysis
batch, prior to conducting any field sample analyses using an Initial Calibration Check
Standard. Continuing Calibration Check Standards and End Calibration Check
Standards are also required as described in the sections below.
10.3.1 INITIAL CALIBRATION CHECK STANDARD (ICCS) - The initial
calibration must be determined to be valid each day prior to analyzing any
samples. Since two detectors are incorporated in this method, this must be
accomplished by using a mixed calibration check standard for the four
conductivity analytes and a separate low level bromate initial calibration check
standard for the absorbance detector. In both cases, the lowest level standard
used to prepare the calibration curve must be used. In cases where the analyst
has chosen to set the MRL above the lowest standard, a standard at a
concentration equal to or below the MRL is acceptable. Percent recovery for the
ICCS must be in the range or 75 - 125% before the analyst is allowed to analyze
samples.
10.3.2 CONTINUING CALIBRATION CHECK/END CALIBRATION CHECK
STANDARDS (CCCS/ECCS) - Continuing calibration check standards must
be analyzed after every tenth field sample analysis and at the end of the analysis
batch as an end calibration check standard. For the reasons noted above, two
separate continuing and end calibration check standards must be incorporated.
If more than 10 field samples are included in an analysis batch, the analyst must
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alternate between the middle and high continuing calibration check standard
levels.
10.3.2.1 The percent recovery for the CCCS/ECCS must meet the following
criteria:
Concentration range Percent Recovery Limits
MRL to 5 x MRL 75 - 125 %
5 x MRL to highest calibration level 85 - 115 %
10.3.2.2 If during the analysis batch, the measured concentration on either
detector differs by more than the calibration verification criteria shown
above, or the retention times shift more than ± 2% from the last
acceptable initial or continuing calibration check standard for any
analyte, all samples analyzed after the last acceptable calibration check
standard are considered invalid and must be reanalyzed. The source of
the problem must be identified and resolved before reanalyzing the
samples or continuing with the analyses.
10.3.2.3 In the case where the end calibration failed to meet performance
criteria, but the initial and middle calibration check standards were
acceptable, the samples bracketed by the acceptable calibration check
standards may be reported. However, all field samples between the
middle and end calibration check standards must be reanalyzed.
11. PROCEDURE
11.1 SAMPLE PREPARATION
11.1.1 For refrigerated or field samples arriving to the laboratory cold, ensure the
samples have come to room temperature prior to conducting sample analysis by
allowing the samples to warm on the bench for at least 1 hour.
11.1.2 Prepare a 10.0 mL aliquot of surrogate fortified sample which can beheld for
direct manual injection or used to fill an autosampler vial. This is done by
adding 20 |_iL of the surrogate solution (Section 7.5) to a 20 mL disposable
plastic micro beaker. Next, place a 10.0 mL aliquot of sample into the micro
beaker and mix. These volumes may be adjusted to meet specific laboratory
autosampler volume requirements provided the fortified surrogate concentration
is at the prescribed concentration of 1.0 mg/L. The sample is now ready for
analysis.
NOTE: The less than 1% dilution error introduced by the addition of the
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surrogate is considered insignificant. In addition, this surrogate fortification
procedure may be omitted if a laboratory chooses to monitor exclusively for
trace bromate using PCR and the UV/VIS absorbance detector, and no other
analytes are being monitored on the conductivity detector. In this situation, the
laboratory must adopt the QC protocol outlined in Section 9.3.3.3.
11.1.3 Using a Luer lock, plastic 10 mL syringe, withdraw the sample from the micro
beaker and attach a 0.45 |_im particulate filter (demonstrated to be free of ionic
contaminants) directly to the syringe. Filter the sample into an autosampler vial
(if vial is not designed to automatically filter) or manually load the injection
loop injecting a fixed amount of filtered, well mixed sample. If using a
manually loaded injection loop, flush the loop thoroughly between sample
analysis using sufficient volumes of each new sample matrix.
11.1.4 CHLORINE DIOXIDE - TREATED WATERS CONTAINING CHLORITE -
Treatment plants that use chlorine dioxide as part of their treatment process can
produce high levels of chlorite in samples. Since chlorite can interfere with the
postcolumn quantitation of low levels of bromate as described in Section 4.6,
chlorite must be removed from these samples prior to analysis.12 The oxidation-
reduction reaction between ferrous iron and chlorite13 is used to remove chlorite
without any adverse affects on the bromate concentration.14 The EDA stabilized
sample is acidified to a pH of 5-6 (verified using pH test strips), ferrous iron
solution is added and allowed to react for 10 minutes. The sample is then
filtered using a 0.45 micron membrane to remove precipitated ferric hydroxide
and the excess soluble iron is removed by passing the filtered sample through a
hydrogen cartridge [a solid phase extraction (SPE) clean-up cartridge in the H+
form, (Section 6.11)], prior to analysis. Prior to using any pretreatment, each lot
of cartridges must be QC checked to insure proper analyte recoveries are
maintained and laboratory reagent blanks are free from interferences. In
addition, consistent lots of reagents, pretreatment cartridges, and membrane
cartridges must be used throughout an entire analysis batch to maintain assured
QC uniformity.
11.1.4.1 Place a 10 mL aliquot of sample in a 20 mL micro beaker and add 35
uL of 0.5 N sulfUric acid (Section 7.8). After mixing, verify thepH is
between 5 and 6 using pH test strips, add 40 uL of ferrous iron solution
(Section 7.7), mix and allow to react for 10 minutes. Filter the
reaction mixture using a 0.45 micron particulate filter (Section 6.10)
attached to a 10 mL syringe into the barrel of a second syringe to
which a pre-conditioned hydrogen cartridge (Section 6.11) is attached.
Pass the solution through a hydrogen cartridge at a flow rate of
approximately 2 mL per minute. Discard the first 3 mL, and collect an
appropriate volume (depending on autosampler vial size) for analysis.
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Add the respective volume of surrogate solution, depending on the
volume collected, and the sample is ready for analysis.
NOTE: Pretreated samples can be held for no more than 30 hours after
initial pretreatment. If this time has expired, the pretreatment steps
must be repeated on a second aliquot of both the field sample matrix
and the respective LFM.
11.1.4.2 In order to ensure data quality, all samples from PWSs which utilize
chlorine dioxide which have been pretreated to remove chlorite,
MUST also be used to prepare a pretreated LFM specific to trace
bromate. This LFM should be fortified with bromate at concentrations
close to but greater than the level determined in the native sample.
Initially, the field sample is analyzed and chlorite, chlorate and
bromide levels are determined. Then, a second aliquot of field sample
is pretreated to remove chlorite, as described above and analyzed to
determine native bromate concentrations. A third aliquot of the field
sample then must be fortified with bromate, pretreated to remove
chlorite, and analyzed to assess bromate recovery from that matrix.
This additional QC is required to rule out matrix effects and to confirm
that the laboratory performed the chlorite removal step appropriately.
If the bromate recovery falls outside the acceptance range of 75 - 125%
(Section 9.4.1.5), that particular sample should be reported as
suspect/matrix.
11.1.4.3 Suppressor devices which have had long term exposure to iron cations
may have reduced method performance in other applications, such as
the determination of certain common inorganic anions. If reduced
peak response is observed, particularly for fluoride or phosphate, the
ASRS should be cleaned according to the manufacturer's
recommendations.
11.2 SAMPLE ANALYSIS
11.2.1 Table 1 summarizes the recommended operating conditions for the ion
chromatograph and delivery of the postcolumn reagent. Included in this table is
estimated retention times that can be achieved by this method. Other columns
or chromatographic conditions may be used if the requirements of Section 9.2
are met.
11.2.2 Establish a valid initial calibration as described in Section 10.2 and complete the
IDC (Section 9.2). Check system calibration by analyzing an ICCS (Section
10.3.1) as part of the initial QC for the analysis batch and, if required,
recalibrate as described in Section 10.3.
317.0-28
-------
11.2.3 Inject 225 |_iL of each sample. Use the same size loop for standards and
samples. An automated constant volume injection system may also be used.
11.2.3.1 Increased sensitivity for low level detection of bromate by PCR can be
achieved by increasing the injected sample volume.4 If the injection
volume is increased (Section 10.2.4) special operating conditions must
be used to insure proper chromatographic performance.4
11.2.4 The width of the retention time window used to make identifications should be
based upon measurements of actual retention time variations of standards
measured over several days. Three times the standard deviation of retention
time can be used to calculate a suggested window size for each analyte.
However, the experience of the analyst should weigh heavily in the
interpretation of chromatograms.
11.2.5 If the response of a sample analyte exceeds the calibration range, the sample
must be diluted with an appropriate amount of EDA fortified reagent water and
reanalyzed. If this is not possible then three new calibration concentrations
must be employed to create a separate high concentration calibration curve, one
standard near the estimated concentration and the other two bracketing around
an interval equivalent to approximately ± 25% the estimated concentration. The
latter procedure involves significantly more time than a simple sample dilution
and, therefore, it is advisable to collect sufficient sample to allow for sample
dilution and sample reanalysis, if required.
11.2.6 Should more complete resolution be needed between any two coeluting peaks,
the eluent (Section 7.2) can be diluted. This will spread out the run, however,
and will cause late eluting anions to be retained even longer. The analyst must
verify that this dilution does not negatively affect performance by repeating and
passing all the QC criteria in Section 9, and by reestablishing a valid initial
calibration curve (Section 10.2). As a specific precaution, upon dilution of the
carbonate eluent, a peak for bicarbonate maybe observed by conductivity within
the retention time window for bromate which will negatively impact the
analysis.
11.2.6.1 Eluent dilution will reduce the overall response of an anion due to
chromatographic band broadening which will be evident by shortened
and broadened peaks. This will adversely effect the MDLs for each
analyte.
11.3 AUTOMATED ANALYSIS WITH METHOD 317.0
11.3.1 Laboratories conducting analyses on large numbers of samples often prepare
317.0-29
-------
large analysis batches that are run in an automated manner. When conducting
automated analyses, careful attention must be paid to all reservoirs to be certain
sufficient volumes are available to sustain extended operation. Laboratories
must ensure that all QC performance criteria are met as described in preceding
sections to ensure their data are of acceptable quality.
11.3.1.1 Special attention must be made when the PCR reservoir is refilled.
Since this is a pneumatically driven system, the baseline will require a
minimum often minutes to restabilize after the reservoir has been
refilled and the bottle repressurized.
11.3.2 Because this method has two detectors that require independent calibration,
analysis sequences must be carefully constructed to meet required QC
specifications and frequency (Table 5). To help with this task, an acceptable
sequence for a sample analysis batch, with all the method-required QC, is shown
in Table 6. This schedule is included only as an example of a hypothetical
analysis batch where the analyst desires to collect data using both detectors.
Within the analysis batch, references to exact concentrations for the ICCS,
CCCS and ECCS are for illustrative purposes only. The analyses for sample
#14 provides an example of the QC requirements for a complete conductivity
and trace bromate PCR analysis of a sample from a PWS employing chlorine
dioxide disinfection.
11.3.3 Table 6 may be used as a guide when preparing analysis batches.
12. DATA ANALYSIS AND CALCULATIONS
12.1 Identify the method analytes in the sample chromatogram by comparing the retention
time of the suspected analyte peak to the retention time of a known analyte peak in a
calibration standard. If analyte retention times have shifted (generally towards shorter
times) since the initial calibration, but are still within acceptance criteria and are
reproducible during the analysis batch, the analyst should use the retention time in the
daily calibrations to confirm the presence or absence of target analytes.
12.2 Compute sample concentration using the initial calibration curve generated in Section
10.2.
12.3 Report ONLY those values that fall between the MRL and the highest calibration
standards. Samples with target analyte responses exceeding the highest standard must
be diluted and reanalyzed. When this is not possible the alternate calibration
procedures described in Section 11.2.5 must be followed. Samples with target analytes
identified but quantitated below the concentration established by the lowest calibration
standard may be reported as present, but below the minimum reporting limit (MRL),
and consequently not quantitated.
317.0-30
-------
12.3.1 Report bromate concentrations using the postcolumn UV/VIS absorbance
detector when they fall between the MRL and 15.0 ug/L. When bromate
concentrations exceed 15.0 ug/L, as detected by UV/VIS absorbance, either
report by conductivity, calibrate the postcolumn UV/VIS absorbance detector to
a higher bromate concentration, or dilute the sample.
12.4 Report results in |_ig/L.
12.5 Software filtering of the postcolumn UV/VIS absorbance signal is required to improve
the precision of peak measurements, minimize non-random noise and improve peak
appearance. Olympic smoothing (25 points, 5 seconds with 1 iteration) was chosen
using peak area for quantitation because it was determined to have minimal effect on
peak height and/or area.2'15 The use of alternate smoothing routines is acceptable
providing all QC criteria are met.
13. METHOD PERFORMANCE
13.1 Table 1 gives the standard conditions, typical retention times and single laboratory
MDLs in reagent water, as determined for each of the inorganic oxyhalide DBFs and
bromide. Included in this table is a comparison of the MDLs determined by
conductivity both with and without the postcolumn UV/VIS absorbance system on-line.
These data indicate that the postcolumn UV/VIS detector system has no effect on
conductivity detector performance (carefUl attention must however be paid to insure
backpressure on the suppressor is kept below 120 psi).
13.2 Table 2 shows the precision and accuracy of the trace bromate measurement, evaluated
on both detectors, at two fortified concentrations, in chlorinated surface water, a
simulated high ionic strength water (HIW) and a simulated high organic (HOW) content
water. The mean bromate recovered concentration (accuracy relative to the fortified
level) and the precision (expressed as %RSD of the replicate analyses) are tabulated.
The HIW was designed to simulate a high ionic strength field sample and the HOW
designed to simulate a high organic content field sample. The HIW was prepared from
reagent water which was fortified with the common anions of chloride at 100 mg/L,
carbonate at 100 mg/L, nitrate at 10.0 mg/L as nitrogen, phosphate at 10.0 mg/L as
phosphorous, and sulfate at 100 mg/L.1 The HOW was prepared from reagent water
fortified with 1.0 mg/L fulvic acid.1
13.3 Table 3 gives the single laboratory standard deviation and precision (% RSD) for each
anion included in the method in a variety of waters for the standard conditions
identified in Table I.1'2
13.4 Table 3 A shows the stability data for the inorganic oxyhalide DBFs. Each data point in
these tables represent the mean percent recovery following triplicate analyses. These
317.0-31
-------
data were used to formulate the holding times shown in Section 8.3.1
14. POLLUTION PREVENTION
14.1 Pollution prevention encompasses any technique that reduces or eliminates the quantity
or toxicity of waste at the point of generation. Numerous opportunities for pollution
prevention exist in laboratory operation. The EPA has established a preferred hierarchy
of environmental management techniques that places pollution prevention as the
management option of first choice. Whenever feasible, laboratory personnel should use
pollution prevention techniques to address their waste generation. When wastes cannot
be feasiblely reduced at the source, the Agency recommends recycling as the next best
option.
14.2 Quantity of the chemicals purchased should be based on expected usage during its
shelf-life and disposal cost of unused material. Actual reagent preparation volumes
should reflect anticipated usage and reagent stability.
14.3 For information about pollution prevention that may be applicable to laboratories and
research institutions, consult "Less is Better: Laboratory Chemical Management for
Waste Reduction," available from the American Chemical Society's Department of
Government Regulations and Science Policy, 1155 16th Street N.W., Washington B.C.
20036, (202) 872-4477.
15. WASTE MANAGEMENT
15.1 The Environmental Protection Agency requires that laboratory waste management
practices be conducted consistent with all applicable rules and regulations. Excess
reagents, samples and method process wastes should be characterized and disposed of
in an acceptable manner. The Agency urges laboratories to protect the air, water, and
land by minimizing and controlling all releases from hoods and bench operations,
complying with the letter and spirit of any waste discharge permit and regulations, and
by complying with all solid and hazardous waste regulations, particularly the hazardous
waste identification rules and land disposal restrictions. For further information on
waste management consult the "Waste Management Manual for Laboratory Personnel,"
available from the American Chemical Society at the address listed in Section 14.3.
16. REFERENCES
1. U.S. EPA Method 300.1. EPA Document number: EPA/600/R-98/118. NTIS number
PB98-169196INZ.
317.0-32
-------
2. Wagner, H.P., Pepich, B.V., Hautman, D.P. and Munch, D.J. "Analysis of 500 ng/L Levels
of Bromate in Drinking Water by Direct Injection and Suppressed Ion Chromatography
Coupled with a Single, Pneumatically Delivered Postcolumn Reagent." Journal
ChromatographvA. 850 (1999), 119-129.
3. Wagner, H.P., Alig, A.E., Pepich, B.V., Frebis, C.P., Hautman, D.P. and Munch, D.J. "A
Study of Ion Chromatographic Methods for Trace Level Bromate Analysis in Drinking
Water Comparing the Selective Anion Concentration (SAC) Method, U.S. EPA 300.1 and a
Postcolumn Reagent Procedure." AWWA WOTC Proceedings. 4D-1, San Diego, CA,
(November 1998).
4. Wagner, H.P., Pepich, B.V., Hautman, D.P. and Munch, D.J. "Performance Evaluation of a
Method for the Determination of Bromate in Drinking Water by Ion Chromatography (EPA
317.0) and validation of EPA Method 324.0 " Presented at the International Ion
Chromatography Symposium, San Jose, CA, September, 1999. Accepted for publication
Journal of ChromatographvA. (anticipated) June 2000.
5. Glaser, J.A., Foerst, D.L., McKee, G.D., Quave, S.A., and Budde, W.L. "Trace Analyses
for Wastewater," Environmental Science and Technology. Vol. 15, Number 12, page 1426,
December, 1981.
6. "OSHA Safety and Health Standards, General Industry," (29CFR1910). Occupational Safety
and Health Administration, OSHA 2206, (Revised, Jan. 1976).
7. ASTM Annual Book of Standards, Part II, Volume 11.01, D3370-82, "Standard Practice for
Sampling Water," American Society for Testing and Materials, Philadelphia, PA, 1986.
8. "Carcinogens-Working with Carcinogens," Publication No. 77-206, Department of Health,
Education, and Welfare, Public Health Service, Center for Disease Control, National
Institute of Occupational Safety and Health, Atlanta, Georgia, August 1977.
9. "Safety In Academic Chemistry Laboratories," 3rd Edition, American Chemical Society
Publication, Committee on Chemical Safety, Washington, D.C., 1979.
10. Standard Methods for the Examination of Water and Wastewater, "Method 4500-C1O 2,C
Amperometric Method I (for the determination of Chlorine Dioxide)," 19th Edition of
Standard Methods (1995).
11. Hautman, D.P. & Bolyard, M. "Analysis of Oxyhalide Disinfection By-products and other
Anions of Interest in Drinking Water by Ion Chromatography." Journal of Chromatographv.
602, (1992 ), 65-74.
317.0-33
-------
12. Wagner, H.P., Pepich, B.V., Hautman, D.P. and Munch, D.J. "The Use of EPA Method
300.1 with the Addition of a Postcolumn Reagent for the Analysis of Ultra Trace Levels of
Bromate in Drinking Water and the Analysis of Bromate in Bottled Waters." Presented at
Pittcon 99, Orlando FL, paper 1414, (March 1999).
13. latrou, A. and Knocke, W.R. Removing Chlorite by the Addition of Ferrous Iron. Journal of
the AWWA Research and Technology, (November, 1992), 63-68.
14. Wagner, H.P., Pepich, B.V., Hautman, D.P. and Munch, D.J. "Eliminating the Chlorite
Interference in US Environmental Protection Agency Method 317.0 Permits the Analysis of
Bromate in all Drinking Water Matrices." Accepted for publication in Journal of
Chromatography A. (anticipated) Fall 2000.
15. Schibler, J.A. American Laboratory. (December, 1997), 63-64.
16. Dixon, W.J. "Processing Data Outliers." Biometrics. BIOMA 9 (No.l):74-89 (1953).
317.0-34
-------
17. TABLES. DIAGRAMS. FLOWCHARTS AND VALIDATION DATA
TABLE 1. CHROMATOGRAPHIC CONDITIONS AND METHOD DETECTION
LIMITS IN REAGENT WATER FOR THE INORGANIC OXYHALIDE
DISINFECTION BY-PRODUCTS AND BROMIDE.
Standard Conditions and Equipment*
a).
Ion Chromatograph:
Sample Loop:
Eluent:
Eluent Flow:
Columns :
Typical System Backpressure:
Suppressor:
Detectors:
Dionex DX500
225 |iL
9.0mMNa2CO3
1.3 mL/min
Dionex AG9-HC / AS9-HC, 4 mm
2300 psi
ASRS-I, external water mode, 100 mA current
Suppressed Conductivity Detector, Dionex CD20
Background Conductivity: 24 |j,S
Absorbance Detector, Dionex AD20 (10mm cell path)
Set for absorbance at 450 nm (Tungsten lamp)
0.7 mL/min
Postcolumn Reactor Coil: knitted, potted for heater, 500 uL internal volume
Postcolumn Heater: 80 °C
Recommended methodtotal analysis time: 25 minutes
Analyte Retention Times and Method Detection Limits (MDLs):
Postcolumn Reagent Flow:
Analyte
Chlorite(c)
Chlorite(d)
Bromate(c)
Bromate(d)
Bromate(e)
Surrogate: DCA(d)
Bromide(c)
Bromide(d)
Chlorate(c)
Chlorate(d)
Retention Time (b)
(min.)
4.20
4.20
4.85
4.85
5.35
8.50
10.0
10.0
11.0
11.0
MDL
Fortified Cone.
(ng/L)
2.0
2.0
2.0
2.0
0.50
2.0
2.0
2.0
2.0
DETERMINATION
#of
Reps.
8
8
8
8
7
8
8
8
8
MDL
0.45
0.89
0.98
0.71
0.12
0.54
0.69
0.92
0.62
(a) Mention of trade names or commercial products does not constitute endorsement or recommendation
for use.
(b) Reference to chromatograms in Figure 2 and 3.
(c) Method 317.0 conductivity detection without PCR online.
(d) Method 317.0 conductivity detection with PCR online.
(e) Method 317.0 ONLY bromate bypostcolumn UV/VIS absorbance detection.
317.0-35
-------
TABLE 2. SINGLE LABORATORY PRECISION IN VARIOUS MATRICES FOR
BROMATE BY CONDUCTIVITY AND ABSORBANCE DETECTION.
Matrix Detection
Reagent Conductivity
Water
Conductivity
Absorbance
Absorbance
Chlorinated Conductivity
Drinking Water
Conductivity
Absorbance
Absorbance
High Ionic Conductivity
Water
Conductivity
Absorbance
Absorbance
High Conductivity
Organic
Water Conductivity
Absorbance
Absorbance
Fortified
Cone.
(ng/L)
0.50
5.0
0.50
5.0
0.50
5.0
0.50
5.0
0.50
5.0
0.50
5.0
0.50
5.0
0.50
5.0
PRE
# of Reps.
8
8
8
8
8
y(b)
8
8
8
8
8
8
8
8
8
8
CISION
Mean
(ng/L)
< MRL(a)
4.8
0.50
5.4
-------
TABLE 3. SINGLE-LABORATORY PRECISION AND RECOVERY FOR THE INORGANIC
DISINFECTION BY-PRODUCTS AND BROMIDE.12
Analyte
Chlorite
Bromate
by
Conductivity
Matrix
RW
HIW
sw
GW
C1W
CDW
O3W
RW
HIW
SW
GW
C1W
CDW
O3W
Unfortified
Cone.
(ng/L)
-------
TABLE 3. SINGLE-LABORATORY PRECISION AND RECOVERY FOR THE INORGANIC
DISINFECTION BY-PRODUCTS AND BROMIDE (cont.).12
Analyte Matrix
Bromide RW
HIW
sw
GW
C1W
CDW
O3W
Chlorate RW
HIW
SW
GW
C1W
CDW
O3W
Unfortified
Cone.
Og/L)
-------
TABLE 3. SINGLE-LABORATORY PRECISION AND RECOVERY FOR THE INORGANIC
DISINFECTION BY-PRODUCTS AND BROMIDE (cont.).12
Analyte
Surrogate: DCA
(see Note)
Matrix
RW
HIW
sw
GW
C1W
CDW
O3W
Fortified
Cone.
(mg/L)
5.0
5.0
5.0
5.0
5.0
5.0
5.0
#of
Reps.
9
9
9
9
9
9
9
Mean
(mg/L)
5.1
5.0
5.0
5.0
4.9
5.0
5.1
5.1
5.2
5.1
5.0
5.0
5.0
5.1
Mean
%REC
102
99.5
100.
99.2
98.9
99.8
102
103
103
103
100.
101
99.8
101
SD(n-l)
0.93
0.69
0.79
1.76
0.70
1.60
0.50
0.50
1.73
1.12
1.02
1.08
0.70
0.53
%RSD
0.91
0.69
0.79
1.78
0.7
1.61
0.49
0.49
1.68
1.09
1.02
1.07
0.7
0.52
RW = Reagent Water
HIW = High Ionic Strength Water
SW = Surface Water
GW = Groundwater
C1W = Chlorinated Drinking Water
CDW = Chlorine Dioxide Treated Drinking Water
O3 W = Ozonated Drinking Water
NOTE: The surrogate DCA was fortified at 5 mg/L but due to concerns about measuring trace concentrations
of bromide with such high concentration of the neighboring surrogate peak, the recommended
fortified concentration for the surrogate has been reduced to 1.00 mg/L.
317.0-39
-------
TABLE 3A. STABILITY STUDY RESULTS FOR THE INORGANIC DISINFECTION BY-
PRODUCTS AND BROMIDE.1
Unfortified Fortified
Analyte % Recovery
Analyte
Chlorite
Chlorite
Bromate
Bromate
Preservative Matrix
None RW
HIW
SW
GW
C1W
CDW
O3W
EDA RW
HIW
SW
GW
C1W
CDW
O3W
None RW
HIW
SW
GW
C1W
CDW
O3W
EDA RW
HIW
SW
GW
C1W
CDW
O3W
uonc.
-------
TABLE 3A. STABILITY STUDY RESULTS FOR THE INORGANIC DISINFECTION
BY-PRODUCTS AND BROMIDE (cont.).12
Unfortified Fortified I
Analyte % Recovery
Analyte
Bromide
Bromide
Chlorate
Chlorate
Preservative Matrix
None RW
HIW
SW
GW
C1W
CDW
O3W
EDA RW
HIW
SW
GW
C1W
CDW
O3W
None RW
HIW
SW
GW
C1W
CDW
O3W
EDA RW
HIW
SW
GW
C1W
CDW
O3W
^UilU.
(|ig/L)
-------
TABLE 4. INITIAL DEMONSTRATION OF CAPABILITY QC REQUIREMENTS.
Reference
Requirement
Specification and Frequency
Acceptance Criteria
Sect. 9.2.2
9.3.1
Initial
Demonstration of
Low System
Background
Analyze a method blank (LRB) and determine
that all target analytes are below % of the
proposed MRL prior to performing the IDC
The LRB
concentration must be
< :/2 of the proposed
MRL
Sect. 9.2.3
Initial
Demonstration of
Precision (IDP)
Conductivity: analyze 7 replicate LFBs
recommend fortify at 20 ug/L
Absorbance: analyze 7 replicate LFBs
recommend fortify with bromate at 2.0 ug/L
%RSDmustbe<20%
Sect. 9.2.4
Initial
Demonstration of
Accuracy (IDA)
Calculate average recovery of IDP replicates
Mean % recovery
must be ± 15% of true
value.
Sect. 9.2.5
Quality Control
Sample (QCS)
Initially and at least quarterly analyze a QCS
from an external/second source
QCS must be ± 20%
of the true value
Sect. 9.2.6
Method
Detection Limit
(MDL)
Determination
Select a fortifying level at 3-5 times the
estimated instrument detection limit at or lower
than the MRL. Analyze 7 replicate LFBs
Calculate MDL using equation in Section 9.2.6
- do not subtract blank
Sect. 9.2.7
Minimum
Reporting Level
(MRL)
MRLs MUST be established for all analytes
during the IDC.
The low CAL
standard can be lower
than the MRL, but the
MRL MUST be no
lower than the low
CAL standard
317.0-42
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TABLE 5. QUALITY CONTROL REQUIREMENTS (SUMMARY).
Reference
Requirement
Specification and Frequency
Acceptance Criteria
Sect. 8.3
Sample Holding
Time /
Preservation
Bromate 28 days, refrig. at <6°C /
EDA Preservation
Bromide 28 days, EDA Permitted
Chlorate 28 days, refrig. at <6°C / EDA
Preservation
Chlorite 14 days, refrig. at <6°C / EDA
Preservation
Holding time and temperature
must not be exceeded. EDA
added to all samples
Sect.
11.1.4.1
(specific
to PCR)
Pretreated
Sample
(acidified/Fe [II]
added to remove
chlorite) Holding
Time
ONLY REQUIRED when samples
containing chlorite are pretreated and PCR
is employed to measure trace bromate in
samples.
MAXIMUM PRETREATED SAMPLE
HOLDING TIME: 30 hours
Pretreated sample holding time
must not be exceeded
Sect. 10.2
Initial
Calibration
Conductivity: generate calibration curve
using at least 5 standards
Absorbance: generate calibration curve
using at least 5 bromate standards
MRL MUST be no lower than
the lowest calibration standard
Sect.
10.3.1
Initial
Calibration
Check
Daily, verify calibration of conductivity
detector at the MRL by analyzing an initial
low-level continuing calibration check
standard (ICCS) and a separate low-level
ICCS for the absorbance detector at the
MRL.
Recovery must be 75-125% of
the true value on both detectors
Sect.
10.3.2
Continuing
Calibration and
End Calibration
Checks
Alternately analyze separate mid and high
level CCCS/ECCS after every 10 samples
and after the last sample
MRL to 5 x MRL must have 75
125% recovery on both
detectors
For 5 x MRL to highest CCCS
must have 85 - 115% recovery
on both detectors
Sect. 9.3.1
Laboratory
Reagent Blank
(LRB)
Include LRB with every analysis batch (up
to 20 samples)
Analyze prior to analyzing field samples
All analytes must be
< y2 MRL
Sect.
9.3.1.2
(specific
to PCR)
PRETREATED
Laboratory
Reagent Blank
(LRB)
REQUIRED in any analysis batch which
includes samples which have been
pretreated to remove chlorite prior to PCR
measurement of trace bromate.
PCR measured bromate
< 1A MRL
Sect. 9.3.2
Laboratory
Fortified Blank
(LFB)
Laboratory must analyze LFB in each
analysis batch following the ICCS.
Calculate %REC prior to analyzing
samples
LFB recovery if fortified at cone.
from MRL to 5X MRL must be
75- 125%. For 5X MRL to
highest CCCS must be 85 -
115%. Must have acceptable
recoveries prior to analyzing
samples. Sample results from
batches that fail LFB are invalid
317.0-43
-------
TABLE 5. QUALITY CONTROL REQUIREMENTS (SUMMARY CONTINUED).
Reference
Requirement
Specification and Frequency
Acceptance Criteria
Sect. 9.3.3
Instrument
Performance
Check (IPC)
Calculate Peak Gaussian Factor (PGF)
using equation (Sect. 9.3.3.1) and
monitor retention time for surrogate in
Initial Calibration Check Standard
(ICCS) each day
PGF must fall between
0.80 and 1.15
Ret. Time (RT) for
surrogate must remain
80% of initial RT when
column was new
Sect. 9.4.1
Laboratory
Fortified Sample
Matrix (LFM)
Sect.
11.1.4.2
Must add known amount of each target
analyte to a minimum of 5% of field
samples or at least one within each
analysis batch for both detectors
LFM must be fortified above the native
level and at no greater than 5 x the
highest field sample concentration
Calculate target analyte recovery using
formula (Sect. 9.4.1.3)
When field samples from chlorine
dioxide plants which contain chlorite
are pretreated prior to the PCR
measurement of trace bromate, an
additional LFM must be prepared for
each pretreated field sample (Sect.
9.4.1.5)
Recovery should be
75 - 125%
If fortified sample fails the
recovery criteria, label
both as suspect/matrix.
Sect. 9.4.2
Surrogate
Dichloroacetate is added to all blanks,
samples and standards (if measuring by
conductivity and absorbance)
Calculate recovery using formula in
Section 9.4.2
Surrogate recovery must
be 90- 115%.
Samples that fail surrogate
recovery must be
reanalyzed. If second
analysis fails label result
as suspect/matrix
Sect. 9.4.3
Field or
Laboratory
Duplicates
Analyze either a field or laboratory
duplicate for a minimum of 5% of field
samples or at least one within each
analysis batch for both detectors
Calculate the relative percent difference
(RPD) using formula in Section9.4.3.1
The RPD for
concentrations at MRL to
5 x MRL should be ± 20%
on both detectors, and ±
10% on both detectors
for concentrations at 5 x
MRLtohighestCCCS. If
this range is exceeded,
label both as
suspect/matrix
317.0-44
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TABLE 6. EXAMPLE SAMPLE ANALYSIS BATCH WITH QUALITY CONTROL
REQUIREMENTS
Injection
#
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
Sample
Description
Laboratory reagent blank (LRB)
ICCS conductivity detector (5.0 ug/L)
ICCS absorbance detector (0.5 ngfL)
Laboratory Fortified Blank (LFB) -
conductivity detector
LFB - absorbance detector
Field sample 1
Field sample 1 - Laboratory Duplicate (LD) (a)
Field sample 2
Field sample 2 - Laboratory Fortified Matrix (LFM) (a) at
concentrations specific for conductivity detector
Field sample 2 - LFM specific for trace bromate on the
absorbance detector
Field sample 3
Field sample 4
Field sample 5
Field sample 6
Field sample 7
Field sample 8
Field sample 9
Field sample 1 0
CCCS conductivity detector (75.0 |j,g/L)
CCCS absorbance detector (5.0 (ig/L)
Field sample 1 1
Field sample 12
Acceptance
Criteria
< 1A MRL
3.75to6.25^g/L
0.375 to 0.625 ng/L
± 25 % fortified level
± 25 % fortified level
± 15%RPD
± 25% fortified level
± 25% fortified level
63. 8 to 86.3 ug/L
4.25 to 5.75 ug/L
317.0-45
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23
24
25
26
27
28
29
30
31
32
33
34
Field sample 1 3
Field sample 14 - (finished water from PWS using chlorine
dioxide)
PretreatedLRB (Section 9.3.1.2) using the acid/Fe(II)
chlorite removal procedure (Section 1 1.1.4)
Field sample 14 (b) - (finished water from PWS using
chlorine dioxide) pretreated with acid/Fe(II) (Section
11.1.4)
Field sample 14 - (finished water from PWS using chlorine
dioxide) LFM specific for trace bromate on the absorbance
detector, pretreated with acid/Fe(II) (Section 1 1.1.4.2)
Field sample 1 5
Field sample 1 6
Field sample 1 7
Field sample 1 8
Field sample 19(b)
ECCS conductivity detector (500.0 (ig/L)
ECCS absorbance detector (15.0 ng/L)
< y2 MRL
± 25% fortified level
425 to 575 ng/L
12. 8 to 17.3 (ig/L
(a) If no analytes are observed above the MRL for a sample, an alternate sample which contains reportable
values should be selected as the laboratory duplicate. Alternately, the LFM can be selected and
reanalyzed as the laboratory duplicate ensuring the collection of QC data for precision.
(b) Field sample #19 was the final field sample permitted in this batch but 20 total field samples were
analyzed.
Field sample #14 was analyzed both initially and as a acid/Fe (II) pretreated sample, therefore, it
accounted for two "field sample analyses" toward the maximum of twenty in an analysis batch (Section
3.1).
317.0-46
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System Configuration for EPA Method 317.0
Eluent
Auto sampler
DX -500
Injection loop
AG9-HC
AS9-HC
PC10PCR
Reservoir
Electrolytic
Suppressor
Abs or bance
Detector
Conductivity
Detector
Knitted Reaction Coil
PCH-2 Heater (ffi 60 °C
Effluent to waste
Figure 1: Schematic detailing the configuration of postcolumn hardware addition to an ion
chromatograph. Mention of trade names or commercial products does not constitute
endorsement or recommendation for use. If the requirements found in Section 9 are met,
equivalent products or hardware can be employed.
NOTE: In a typical Method 300.1 hardware configuration, a backpressure coil is included after
the conductivity cell as part of the waste stream when this manufacturer's equipment is used.
These backpressure coils are not required when the Method 317.0 instrument configuration is
employed since the additional PCR system components, placed in-line, function in the same
capacity and provide sufficient backpressure.
317.0-47
-------
0.500r
0.400 --
0.100 -
-0.100 --
Surrogate:
DCA X
bromate
chlorite
bromide chlorate
Conductivity Detector
2.50 5.00 7.50 10.00 12.50 15.00 17.50 20.00 22.50 25.00
Minutes
2.00x10-V
1.50X10"3--
1.00x10"*--
5.00x10"*--
bromate
I
UV7VIS Detector at 450 nm
2.50 5.00 7.5D
10.00
Minutes
12.50 15.00 17,50 20.00 22.50 25.00
Figure 2: Reagent water fortified with inorganic disinfection by-products and bromide at 10
ug/L.
317.0-48
-------
0.400
0,200
0.100--
-0.200 L
0
Surrogate^
DCA
bromate
2.50 S.OO
Conductivity Detector
7.50 10.00
Minutes
12.SO 15.00 17.50 20.00 22.60 25.00
1.00x10 --
bromate
UV/VIS Detector at 450 nm
-8.00x10 -I—f
0
2.50 S.OO 7.50
10.00 12.60
Minutes
19MU 17.50 20.00 22.50 25.00
Figure 3: Chlorinated tap water fortified with bromate at 2.0 ug/L.
317.0-49
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