METHOD 334.0:  DETERMINATION OF RESIDUAL
            CHLORINE IN DRINKING WATER USING AN ON-LINE
            CHLORINE ANALYZER
Office of Water (4606 M)  EPA 815-B-09-013  September 2009   www.epa.gov/safewater

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METHOD 334.0:     DETERMINATION OF RESIDUAL CHLORINE
                   IN DRINKING WATER USING AN ON-LINE
                   CHLORINE ANALYZER
                         Version 1.0

                       September 2009
    Steven C. Wendelken, Derek E. Losh, and Patricia S. Fair
         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 334.0

           DETERMINATION OF RESIDUAL CHLORINE IN DRINKING WATER
                       USING AN ON-LINE CHLORINE ANALYZER

1.      SCOPE AND APPLICATION

       1.1    This method is for the analysis of residual chlorine (free or total) in drinking
             water. It is primarily intended to be used by drinking water utilities for
             compliance with daily monitoring requirements. This method allows the use of
             any type of on-line chlorine analyzer (e.g., amperometric, DPD, etc.) for
             compliance monitoring when used in conjunction with a grab sample reference
             method that is approved for drinking water compliance monitoring. This method
             is intended to be used when chlorine residuals (free or total) are in the range of
             0.2 mg/L to 4 mg/L.

       1.2    The grab sample reference method must be listed in the methods table of the
             regulation under which the monitoring is being conducted. (A method in
             Appendix A may be used if it is listed as approved for the regulation.)  Color
             wheels or optical comparison scales are not allowed for methods which specify
             the use of a spectrophotometer.
2.      SUMMARY OF METHOD

       2.1    An on-line chlorine analyzer is used to continuously monitor the chlorine
             concentration at a drinking water sample point. The instrument is calibrated using
             aqueous standards or the results from paired grab samples that are collected at the
             same sample point and time. The grab samples are analyzed for chlorine (free or
             total) using a method that is approved for drinking water compliance monitoring.
             The on-line analyzer accuracy is periodically verified/adjusted based on results
             from grab sample analyses.
3.      INTERFERENCES

       3.1    A general discussion of potential interferences to the grab sample measurements
             is included in Standard Method 4500-C1 A.1  More specific information is
             included with each reference method and should guide the user when selecting a
             method.  Amperometric titration methods are less subject to interferences from
             common oxidizing agents, turbidity and color.  Organic contaminants and high
             concentrations of monochloramine may produce false free chlorine readings in
             colorimetric methods.  Colorimetric methods specify procedures to reduce
             interferences from copper, chromate, and reduced manganese.  Strong oxidizing
             agents (e.g., permanganate, ozone) interfere with free chlorine measurements in
             all methods.

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       3.2     Consult the manufacturer's literature regarding potential interferences to the
              measurements by on-line chlorine analyzers. Amperometric analyzers are
              sensitive to pH, flow and temperature changes, but compensation for these
              variables is usually incorporated into the design of the analyzer.  DPD analyzers
              are subject to the same interferences as the DPD grab sample methods.
4.      SAFETY
       4.1     The toxicity or carcinogenicity of each reagent used in this method has not been
              precisely identified; each chemical compound should be treated as a potential
              health hazard, and exposure to these chemicals should be minimized.  The
              lab oratory/water system is responsible for maintaining documentation of OSHA
              regulations regarding the safe handling of the chemicals specified in this method.
              A reference file of Material Safety Data Sheets (MSDS) should also be made
              available to all personnel involved in the chemical analysis. Additional references
              to laboratory safety are available.2"5
5.      EQUIPMENT AND SUPPLIES

       5.1     ON-LINE CHLORINE ANALYZER - The selection of an analyzer must
              consider the water quality characteristics of the drinking water, the treatment
              process, and the physical location of the analyzer installation.  Some of the water
              quality parameters to consider include variability in the water pH, temperature,
              ionic strength and the presence of potential interferences such as iron, manganese,
              and copper. The treatment process dictates whether the on-line analyzer must
              measure free or total chlorine residuals.  The concentration of residual chlorine
              being measured establishes the required instrument range.  The range should be
              as small as possible, while still bracketing  expected concentrations (e.g., Residual
              concentrations in the range of 0.5 to 1.5 mg/L should be monitored using an
              analyzer with a linear dynamic range of 0 to 2 mg/L rather than 0 to 10 mg/L.)
              The analyzer must be installed according to the manufacturer's instructions so
              that changes in pressure or flow will not influence the analyzer measurements.
              Install the analyzer as close to the sampling point as feasible and in a location that
              is easily accessible for maintenance.  Install a sample tap as close as feasible to
              the location where the sample enters the analyzer to allow for collection of
              discrete grab samples for calibration and accuracy verification.

              5.1.1.   The analyzer must have a readout at its installation location and the
                      readings must be continually recorded (hard copy chart or electronic
                      data). For remote installations, the analyzer should also have the
                      capability for transmission of the  output to a centralized location.

              5.1.2.   The on-line monitoring system should have the capability to activate an
                      alarm when the chlorine concentration is outside the normal operating
                      range.

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             5.1.3.   The analyzer must allow manual adjustment for calibration.

       5.2    GRAB SAMPLE REFERENCE METHOD - Amperometric titration or N,N-
             Diethyl-p-phenylenediamine (DPD) colorimetric methods are the most commonly
             used approved grab sample methods. Additional choices are included in the
             methods table of the regulation under which monitoring is being conducted.
             Consult the method for a listing of equipment and supplies.

       5.3    GLASSWARE - Free of chlorine demand. See ASTM D 1253-03 6 or Standard
             Method 4500-C1 Dl, if glassware needs to be treated to remove chlorine demand.

             5.3.1.   BEAKERS - Varying sizes.

             5.3.2.   VOLUMETRIC FLASKS - Class A, of varying sizes.

             5.3.3.   PIPETTES - Class A, varying sizes or a variable volume single channel
                     pipette with disposable plastic tips, (e.g., Eppendorf Series 2000 pipetter,
                     No. 022470302; or Hach Tensette® pipette, No 1970001)
6.     REAGENTS AND STANDARDS

      6.1    REFER TO THE ON-LINE CHLORINE ANALYZER OPERATING MANUAL
             FOR A LIST OF REAGENTS SPECIFIC TO THE INSTRUMENT- Reagent
             grade or better chemicals should be used. Unless otherwise indicated, all reagents
             should conform to the specifications of the Committee on Analytical Reagents of
             the American Chemical Society, where such specifications are available. Other
             grades may be used, provided it is first determined that the reagent is of
             sufficiently high purity to permit its use without lessening the quality  of the
             determination. Reagents must be stored  according to the manufacturer's
             recommendations and only used within the manufacturer's designated lifespan
             (prior to expiration date).

      6.2    REFER TO THE SELECTED GRAB SAMPLE METHOD FOR A LIST OF
             REAGENTS SPECIFIC TO THE METHOD - Reagent grade or better chemicals
             should be used. Unless otherwise indicated, all reagents should conform to the
             specifications of the Committee on Analytical Reagents of the American
             Chemical Society, where such specifications are available. Other grades may be
             used, provided it is first determined that the reagent is of sufficiently high purity
             to permit its use without lessening the quality of the determination. Titrants that
             are purchased in their diluted form, ready to use in the grab sample method,
             should be NIST traceable or certified in an equivalent manner. Reagents must be
             stored according to the manufacturer's recommendations and only used within the
             manufacturer's designated lifespan (prior to expiration date).

      6.3    REAGENT WATER - Purified water (typically either deionized or distilled) is
             usually acceptable. Reagent water can be purchased from a scientific supply
             company, if it is not available on site.  If a chlorine demand is present, suggested

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             procedures for preparing chlorine demand-free water are included in ASTM D
             1253-03 6 and Standard Method 4500-C1 C \

       6.4    CALIBRATION STANDARD SOLUTIONS - Use the type of aqueous standard
             (e.g., chlorine or potassium permanganate) specified in the selected grab sample
             method.  A concentrated stock standard solution can be purchased from a
             commercial source (e.g., Environmental Resource Associates, Catalog # 696;
             Hach, Product # 1426820, or equivalent). A purchased stock standard must be
             NIST traceable or certified in an equivalent manner.  The stock standard must be
             stored according to the manufacturer's recommendations and only used within the
             manufacturer's designated lifespan (prior to expiration date). The stock solution is
             diluted using reagent water to obtain calibration standard  solutions in the range of
             0.2 mg/L to 4.0 mg/L.  Calibration standards should be prepared fresh for each
             use unless manufacturer's instructions specify otherwise.

       6.5    ROUTINE GRAB SAMPLE CALIBRATION CHECK STANDARD -
             Calibration standards prepared above may also be used as calibration check
             standards. Calibration check standards must be freshly prepared.

       6.6    SECONDARY STANDARD - Colorimetric standards may be purchased for use
             with DPD spectrophotometers/colorimeters. The accuracy of secondary standards
             must be verified on each recently-calibrated spectrophotometer/colorimeter for
             which they will be used.  Secondary standards may not be used to calibrate the
             sp ectrophotometer.

       6.7    INDEPENDENT REFERENCE  SAMPLE - Purchase a chlorine standard
             solution that is NIST traceable or certified in an equivalent manner from a
             different source than the  source of the calibration standards. Calibration standards
             and the independent reference samples that are purchased from the same supplier
             must be from different lots.  The independent reference sample must be stored
             according to the manufacturer's recommendations and only used within the
             manufacturer's designated lifespan (prior to expiration date).
7.      SAMPLE COLLECTION, PRESERVATION, AND STORAGE

       7.1    SAMPLE COLLECTION - The grab sample collection point should be as close
             as possible to the location where the sample enters the on-line chlorine analyzer,
             so that the grab sample reflects the same water as the on-line analyzer is
             measuring. A sample line may be equipped with a valve (e.g., T or Y
             configuration) that allows for intermittent grab sampling with minimal disruption
             of flow to the analyzer. Follow the sample collection instructions specified in the
             grab sample method. Collect the grab sample with minimal agitation. Exposure
             to sunlight or strong light will cause loss of chlorine. Begin analysis immediately
             after sample collection. Do not store samples.

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8.      QUALITY CONTROL

       8.1    Quality control (QC) procedures are incorporated into analytical methods in order
             to demonstrate that the results are valid and within the accuracy and precision
             ranges needed for protection of public health. Grab sample methods for
             measuring chlorine residuals are designed to be independent of other chlorine
             measurement methods. As a result, some of the normal QC requirements may not
             be necessary when the grab  sample method is used in conjunction with an on-line
             chlorine analyzer. For example, Part 4020 in Standard Methods l indicates daily
             analysis of method blanks, calibration check standards, fortified blanks, and
             duplicates (with each batch of samples). Although these QC samples are useful
             and may be included as part of the standard operating procedure (SOP), they are
             not necessary when the grab sample measurement is being compared to an
             analyzer measurement because the comparison of the two measurements serves as
             a QC check. If grab sample analyses are only being performed in conjunction
             with on-line chlorine analyzers, the analyst is only required to follow the
             minimum requirements set forth in this method. However, this method is not
             intended to supersede the QC requirements that are requisite when the data are
             used for other purposes.

       8.2    The requirements of the QC program for the grab sample method that is used as
             the reference for the on-line chlorine analyzer consist of an Initial Demonstration
             of Capability  (IDC)  and periodic analyses of calibration check standards and
             independent reference samples. The  QC program for the on-line chlorine
             analyzer consists of an IDC  and periodic comparisons of the instrument reading to
             results of a sample analyzed using the grab sample reference method. These QC
             procedures and the acceptance criteria are described in Sections 10  and 11 of this
             method. It is  desirable to maintain consistency with regard to personnel
             responsible for instrument QA/QC checks and related field sampling.

       8.3    OPTIONAL QC - Laboratories/water systems are encouraged to institute
             additional QC practices to meet their specific needs. The remainder of this
             section describes various optional QC procedures that may be incorporated into a
             QC program for grab sample verification of on-line chlorine analyzer
             performance.

             8.3.1.   GRAB  SAMPLE DUPLICATE - Analysis of duplicate grab samples
                     (two samples collected at the same time) provides an estimate of the
                     precision of the grab sample analyses that are used to verify/adjust the
                     accuracy of the on-line chlorine analyzer.  Poor grab sample precision
                     can cause problems in the analyzer adjustment. Analysis of grab sample
                     duplicates is suggested when there are difficulties in adjusting the
                     analyzer calibration to agree with the grab sample measurement.
                     Calculate the relative percent difference (RPD) between the Sample
                     (FD1) and the Sample Duplicate (FD2) as  shown below. The RPD for
                     samples with concentrations greater than the lowest calibration standard
                     should not exceed 15%.  The RPD at concentrations at or near the lowest
                     calibration  standard should not exceed 50%.

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                                      FD1-FD21
                              RPD = -,	J- x 100%
                                     (FDl + FD2)/2

                      If the RPD for the Sample and the Sample Duplicate falls outside the
                      designated range, perform duplicate analyses of a calibration check
                      standard to verify that the grab sample method is in control.

             8.3.2.    INDEPENDENT REFERENCE SAMPLE - Analysis of a  sample from
                      an external source (different from the calibration standards) provides an
                      independent check of the calibration of the grab sample method.  It is
                      recommended semiannually or any time a new calibration curve is
                      generated.

             8.3.3.    PROFICIENCY TESTING (PT) or PERFORMANCE EVALUATION
                      (PE) SAMPLE - Successful participation in  a PT or PE Study is a good
                      QC tool for demonstrating proficiency with the grab sample method. A
                      certified solution of chlorine whose concentration is unknown to the
                      analyst can be purchased by the laboratory/water system. An aliquot of
                      the certified solution  is added to a known volume of reagent water and
                      analyzed as a grab sample. The analytical results are reported to the
                      PT/PE Study Provider where they are compared to data from all analyses
                      of the sample. Acceptance criteria are established for each  study.
                      Generally, a different analyst should participate in each study, so that
                      over time each analyst has an opportunity to  demonstrate proficiency. If
                      the analyst is a field sampler, the sample can be prepared by laboratory
                      personnel for the analyst.

9.      CALIBRATION

       9.1    An acceptable initial calibration for the grab sample method must be established
             before the results from the grab sample method can be used to verify the accuracy
             of an on-line chlorine analyzer.  After initial calibration is successful, a calibration
             check standard or independent reference sample is periodically analyzed to verify
             that the grab sample method calibration is still valid.

       9.2    The calibration of the on-line chlorine analyzer is verified against a grab sample
             measurement.  (On-line chlorine analyzers that use the same chemistry as an
             approved grab sample method may use aqueous standards for initial  calibration
             verification instead of comparison to grab sample measurements. Routine
             calibration checks are made by comparison with grab  sample measurements.)

       9.3    The calibration procedures and acceptance criteria are described in Sections 10
             and 11 of this method.

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10.    START-UP PROCEDURES

       10.1   GRAB SAMPLE METHOD - Refer to the selected grab sample method for a
             complete description of the procedure. (Each drinking water regulation includes a
             tabular listing of methods that are approved for analyses of compliance samples.
             The regulation also identifies how to obtain a copy of each method.) Section 15 -
             Table  1 and Flowchart 1 summarize the start up QC for the grab sample method.

             10.1.1.  Prepare or verify the initial calibration curve. This must be done for
                      each meter or titrator according to the procedure described below. The
                      accuracy of secondary standards must also be verified. These steps can
                      be performed by laboratory personnel or field samplers. A record of the
                      calibration results must be maintained for each meter/titrator.

                      10.1.1.1. Prepare a method blank (reagent water) and a set of at least
                              three aqueous calibration standards.  The lowest concentration
                              calibration standard must be at or below 0.2 mg/L or the
                              minimum chlorine residual required by the state. The standards
                              must span the concentration range that is expected to be
                              observed in the grab samples. (Note: If the range extends
                              above the maximum concentration specified for the DPD
                              reagents and colorimeter, prepare three standards within the
                              range specified by the manufacturer and a fourth standard at
                              the highest concentration expected for the grab  samples.)

                      10.1.1.2. Analyze the calibration standards and method blank according
                              to the grab sample procedure. (Note: If the highest
                              concentration standard is above the maximum concentration
                              specified for the DPD reagents and colorimeter, dilute and
                              analyze it according to manufacturer's instructions.  Use the
                              data from this analysis to check the accuracy of the  dilution
                              process, not the calibration curve.)

                              10.1.1.2.1.  For methods that do not require the preparation of a
                                         curve or that use an internal, factory set calibration
                                         curve, compare the measured concentration of each
                                         standard to the expected value.  Each calibration
                                         point must be within ± 15% of its expected value.
                                         If the internal curve does not meet these  criteria, the
                                         internal curve must be updated by following the
                                         manufacturers' instructions for generating/inputting
                                         a  curve.  Otherwise, send the meter to the vendor
                                         for repair/updating.

                              10.1.1.2.2.  For methods that require the preparation of a curve,
                                         use the concentration of each standard versus the
                                         instrument response to calculate the best fit curve
                                         according to the procedure described in the grab

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                           sample method. Validate the curve by calculating
                           the concentration of each standard using the curve.
                           Each calibration point must be within ± 15% of its
                           expected value.

        10.1.1.3. If secondary standards are available for the grab sample
                 method, they must be verified prior to use by analyzing them
                 immediately after initial calibration is verified. The secondary
                 standards must be within ± 10% of their expected
                 concentrations when compared to the initial calibration curve.
                 New secondary standards must be purchased if this criterion
                 cannot be met.  The secondary standards must meet the
                 criterion on every meter for which they will be used.
                 Secondary standards must be verified each time the initial
                 calibration procedure is repeated.  Secondary standards must
                 not be used beyond the manufacturer's expiration date.

10.1 .2.  Each field sampler must perform an initial demonstration of capability
        (IDC) prior to using the grab sample method to verify the accuracy of
        on-line chlorine analyzers. If the accuracy and precision criteria
        described below are not met, determine the source of the problem, take
        corrective action and repeat the IDC. The IDC consists of a
        demonstration of accuracy and a demonstration of precision using the
        procedure described below.

        10. 1 .2. 1 . INITIAL DEMONSTRATION OF ACCURACY - Prepare
                 and analyze a method blank (reagent water) and five
                 independent reference samples at the same concentration.  The
                 concentration of the samples should be in the mid range of the
                 calibration curve or near the expected concentration of the
                 water samples. Calculate the average chlorine concentration
                 for the five  analyses.  The average concentration for the five
                 replicates must be within ± 15% of the expected value. The
                 method blank concentration must be < l/3 the concentration of
                 the lowest standard used to prepare/verify the calibration curve
                 (Section 10.1.1.1).

        10. 1 .2.2. INITIAL DEMONSTRATION OF PRECISION - Using the
                 same set of replicate data generated for Section 10.1.2.1,
                 calculate the standard deviation and relative standard deviation
                 (RSD) of the replicate values. The RSD is calculated using the
                 equation
                                    X
                 where
                 S is the standard deviation for the replicate values,
                 and X is the average value for the replicates.

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                        The RSD of the results of the replicate analyses must be <15%.

       10.1.3.  Each field sampler must successfully complete the IDC procedure
               described above (Section 10.1.2) prior to using the grab sample method
               in conjunction with an on-line chlorine analyzer.  Laboratory personnel
               may prepare the independent reference samples for analyses by field
               samplers. A record of the IDC results must be maintained for each field
               sampler.

10.2   ON-LINE CHLORINE ANALYZER - Install the analyzer according to the
       manufacturer's specifications. Follow all start-up procedures outlined in the
       operator's manual including specific instructions regarding calibration of the
       analyzer. The following procedure must be followed for each analyzer. (Section
       15 - Table 2 and Flowchart 2 summarize the start-up QC for on-line chlorine
       analyzers.)

       10.2.1.  After the analyzer is providing stable readings, proceed with
               verifying/adjusting the initial calibration.  If the analyzer uses the same
               chemistry as an approved grab sample method, the calibration curve can
               be established/verified using aqueous chlorine standards in a manner
               similar to the grab sample procedure described above in  Section 10.1.1.
               Alternately, calibration of the analyzer may be verified/adjusted based on
               the results of grab sample measurements as described below.  All other
               types of analyzers must use the following procedure:

               10.2.1.1.  Collect and analyze a grab  sample collected as close as feasible
                        to the location where the sample enters the on-line chlorine
                        analyzer. Compare the results from the grab sample analysis to
                        the measurement made by the on-line chlorine analyzer.

               10.2.1.2.  Follow the manufacturer's  instructions to adjust the calibration
                        of the analyzer so it gives the same value as the grab sample
                        analysis.

               10.2.1.3.  Repeat steps 10.2.1.1 and 10.2.1.2 until the on-line chlorine
                        analyzer measurement agrees with the grab sample
                        measurement.  (Ideally, the two measurements will be the
                        same, but realistically this won't always be possible. Note that
                        during routine operation of the analyzer, the readings must be
                        within ± 0.1 mg/L or ± 15% of the grab sample measurement.
                        Use that criterion as a guide for deciding when the analyzer
                        calibration is properly adjusted during this start-up procedure.)

       1022   Conduct  the initial demonstration of capability (IDC) after the
               calibration of the on-line chlorine analyzer has been verified.
               Requirements for the IDC are described in 10.2.2.3.  The full IDC must
               be conducted prior to using the analyzer for compliance monitoring
                                    10

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measurements.  This will take a minimum of 14 days.  The data collected
during the IDC must be recorded and maintained.

10.2.2.1. The IDC for the on-line chlorine analyzer is not required if
         historical operating data for the on-line chlorine analyzer
         demonstrate the criterion are being met on an on-going basis.
         Historical data must show that the analyzer remains in
         agreement with the grab sample method  over a period of two
         consecutive weeks without analyzer maintenance or calibration
         adjustment. Agreement is defined as being within ±0.1 mg/L
         or ± 15% (whichever is larger) of the grab sample
         measurement. The following procedures must be completed
         prior to using the analyzer for compliance monitoring.

        10.2.2.1.1.  Verify the calibration of the grab  sample
                   measurement according to 10.1.1.

        10.2.2.1.2.  Each field sampler must complete the IDC
                   requirements for the grab  sample  measurement
                   according to 10.1.2.

        10.2.2.1.3.  Calibration of the on-line  chlorine analyzer must be
                   verified according to 10.2.1 after the grab sample
                   IDC is completed.

        10.2.2.1.4.  Proceed to 10.2.3.

10.2.2.2. When multiple on-line chlorine analyzers are being installed,
         the primacy agency may allow the IDC to be shortened under
         the following conditions.

        10.2.2.2.1.  The same model analyzer is installed at each
                   location.

        10.2.2.2.2.  The water quality characteristics and treatment
                   processes are equivalent at each location.

        10.2.2.2.3.  A successful IDC (Section 10.2.2.3) is completed
                   for the first analyzer that is placed in service.

        10.2.2.2.4.  The IDC for subsequent analyzers can be shortened
                   to 7 consecutive days (or 7 consecutive business
                   days) of daily grab sample comparisons. The
                   analyzer reading must be within ±0.1  mg/L or ±
                   15% (whichever is larger) of the grab sample
                   measurement for each data pair. When you obtain 7
                   consecutive days (or business days) of data pairs
                     11

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                           that meet the acceptance criterion, proceed to
                           10.2.3.

        10.2.2.3. Compare the concentration determined by the on-line chlorine
                 analyzer with grab sample analyses collected at least daily for
                 14 days.  (If samples cannot be collected during the weekend,
                 14 consecutive business days is acceptable.) During the 14
                 days, grab samples should be collected at concentrations that
                 represent highs and lows, as indicated by the analyzer, (e.g., if
                 the analyzer indicates the chlorine concentration varies
                 between 0.5 mg/L and 1.0 mg/L, grab samples should be
                 collected to verify accuracy at both of these concentrations.)
                 The analyzer reading must be within ±0.1 mg/L or ± 15%
                 (whichever is larger) of the grab sample measurement for each
                 data pair. If this criterion is not met, determine the source of
                 the problem, take corrective action and continue collecting
                 daily grab samples. When you obtain 14 consecutive days (or
                 business days) of data pairs that meet the acceptance criterion,
                 proceed to 10.2.3.

        10.2.2.4. If you are unable to meet the criterion in 10.2.2.3, verify you
                 have chosen an appropriate analyzer for your water quality and
                 operating conditions.  An on-line chlorine analyzer that cannot
                 meet the criterion in 10.2.2.3 may be used for compliance
                 monitoring only if grab sample comparisons are conducted
                 daily or at a frequency approved by the primacy agency.

10.2.3.  Upon successful completion of the IDC, the analyzer can be put into
        service for compliance monitoring.  Control or warning limits should be
        established for the analyzer readings, so that operators are immediately
        alerted to unexpected changes in the chlorine measurements.  For remote
        installations, interfacing the analyzer with a SCADA system, automated
        phone dialer, or a similar notification system is a critical consideration.

10.2.4.  A routine schedule for grab sample comparisons can be established
        based on the results from intense monitoring over the course of the first
        few months  of operation.  The maximum time  between grab samples
        must not exceed once every seven days. (Appendix A provides an
        optional systematic approach for establishing a routine schedule for grab
        sample comparisons. Alternative approaches may be used to determine
        the optimum frequency of grab sample comparisons.)

10.2.5.  All manufacturers' recommendations for routine maintenance should  be
        followed. When maintenance is performed, the accuracy of the analyzer
        must be verified with a  grab sample comparison after the analyzer is
        placed back  in service.  The accuracy must be verified again after one
        day of operation (Section 11.2).  If the accuracy criteria are not met and
                             12

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                     the analyzer is operating properly, adjust the analyzer calibration
                     according to the procedure in Sections 11.2.3 - 11.2.7.
11.    ROUTINE PROCEDURES

      11.1   ROUTINE CALIBRATION CHECK FOR THE GRAB SAMPLE METHOD -
             Prepare an aqueous calibration check standard at a concentration near the
             expected concentration of the water samples. (Over time, vary the grab sample
             calibration check standard concentration when multiple analyzers are being
             verified and the drinking water chlorine concentration at each analyzer is
             different.) The grab sample measured concentration of the calibration check
             standard must be within ± 15% of the expected value. If this criterion is not met,
             the analyst must identify and resolve the problem with the grab sample method
             prior to proceeding with analyses of grab samples to verify the on-line chlorine
             analyzer accuracy.  The results from analyses of calibration check standards must
             be recorded and maintained according to the requirements of the primacy agency.

             11.1.1.   A check standard must be analyzed:

                     11.1.1.1. when the grab sample measurement is used to adjust the
                             calibration of the on-line chlorine analyzer

                     11.1.1.2. a minimum of once quarterly.

             11.1.2.   Analysis of secondary standards is an easy way to verify the
                     spectrophotometer is operating properly for colorimetric methods.
                     Analysis of secondary standards does not replace the analysis of aqueous
                     check standards.  Each secondary standard must be within ± 10% of its
                     expected concentration.

      11.2   ROUTINE CALIBRATION CHECK FOR ON-LINE CHLORINE ANALYZER
             - The accuracy of the on-line chlorine analyzer is monitored during routine use by
             periodic comparisons of the analyzer readings to grab sample measurements. The
             maximum time between grab samples must not exceed once every 7 days (i.e., a
             weekly grab sample). The  analyzer concentration must be within ±0.1 mg/L or ±
             15% (whichever is larger) of the grab sample measurement. (Section 15 - Table
             4 and Flowchart 3 summarize the routine QC for on-line chlorine analyzers.) All
             data from these comparisons must be recorded and maintained according to the
             requirements of the primacy agency.

             11.2.1.   Disagreement between the grab sample and analyzer measurements may
                     indicate a need for maintenance on the analyzer (e.g., flow adjustment,
                     pH adjustment, cleaning, new membrane, fresh reagents, etc.) The
                     operator must conduct trouble-shooting activities and rule out problems
                     with the analyzer prior to making calibration adjustments.
                                          13

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               11.2.1.1. The operator may perform a second comparison between the
                       analyzer and a grab sample to rule out variability in the grab
                       sample as the cause for disagreement.

               11.2.1.2. Follow the manufacturer's instructions for troubleshooting
                       problems with the analyzer.

       11.2.2.   If the analyzer is operating properly, verify that the grab sample
               measurement is accurate by analyzing a grab sample calibration check
               standard (Section 11.1).

               11.2.2.1. For remote sites, the accuracy of the grab sample measurement
                       can initially be verified using secondary standards that have
                       been tested for accuracy according to Section 10.1.1.3. The
                       secondary standards must be within ± 10% of their expected
                       concentration.

               11.2.2.2. If secondary standards are used in the field, a grab sample
                       calibration check standard should be analyzed using the same
                       lot  of reagents within 24 hours unless an alternative time frame
                       is approved by the primacy agency.

       11.2.3.   After the accuracy of the grab sample measurement is verified, follow
               the manufacturer's instructions to adjust the calibration of the analyzer
               so it gives the same value as the grab sample analysis.

       11.2.4.   Confirm that the calibration adjustment is accurate by analyzing another
               grab sample and comparing the result to the reading from the analyzer.

       11.2.5.   Repeat steps 11.2.3 and 11.2.4 until the on-line chlorine analyzer
               measurement agrees with the grab sample measurement. (The two
               measurements should be as close as  possible. Note that during routine
               operation of the analyzer, the readings must be within ±0.1 mg/L or ±
               15% of the grab  sample measurement. Use that criterion as a guide for
               deciding when the analyzer calibration is properly adjusted.)

       11.2.6.   An additional grab sample must be collected and analyzed after one day
               of operation in order to verify that the calibration adjustment was
               performed accurately. If the criterion is not met, follow 11.2.3  -11.2.6 to
               adjust the calibration of the analyzer or take other corrective steps
               consistent with manufacturer instructions.

       11.2.7.   Return to the routine schedule for grab sample comparisons. A grab
               sample must be analyzed at least once each week

11.3    NON-ROUTINE CALIBRATION CHECK FOR ON-LINE CHLORINE
       ANALYZER - Certain conditions may trigger the need to compare the analyzer
       reading to a grab sample measurement outside the routine schedule. When a non-

                                    14

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             routine comparison is made, the analyzer concentration must be within ±0.1
             mg/L or ± 15% (whichever is larger) of the grab sample measurement. If this
             criterion is not met, the operator must take corrective action to bring the analyzer
             back into agreement with the grab sample measurement. The steps in Section
             11.2 must be followed. Problems with the analyzer must be ruled out or fixed
             prior to any calibration adjustment to the on-line chlorine analyzer.

             11.3.1.  The on-line chlorine analyzer measurement must be compared to a grab
                     sample measurement when routine maintenance (such as cleaning,
                     replenishment of reagents, membrane replacement, adjustment of flow
                     rate, pH calibration, etc.) is performed on the analyzer.

             11.3.2.  If the analyzer measurements indicate a gradual drift upward or
                     downward when no changes in chlorine concentration are expected, a
                     grab sample measurement should be performed.

       11.4   EMERGENCY CALIBRATION CHECK FOR ON-LINE CHLORINE
             ANALYZER - If the on-line chlorine analyzer indicates a large (> 50%)
             unexpected change in chlorine residual concentration (based on process control
             and water quality conditions), a grab sample should be collected and analyzed as
             soon as possible. When an emergency comparison is made, the analyzer
             concentration must be within ± 0.1 mg/L or ± 15% (whichever is larger) of the
             grab sample measurement.  If this criterion is not met, the operator must take
             corrective action to bring the analyzer back into agreement with the grab sample
             measurement.  The steps in Section 11.2 must be followed.  Problems with the
             analyzer must be ruled out or fixed prior to any calibration adjustment to the on-
             line chlorine analyzer.

       11.5   RETURNING  AN ON-LINE CHLORINE ANALYZER TO SERVICE - After a
             major repair or after replacement of the on-line chlorine analyzer with an
             equivalent model, follow all start-up procedures outlined in the operator's manual.
             Calibrate according to the procedure in Section 10.2.1.  Return to the routine
             schedule for grab sample comparisons (Section 11.2) after verifying the accuracy
             of the analyzer on a daily basis for 7 consecutive days (or business days) or for a
             period specified by the primacy agency.
12.    POLLUTION PREVENTION

      12.1   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. 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 feasibly reduced at the source, the
             Agency recommends recycling as the next best option.
                                          15

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       12.2   Quantity of a chemical 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.

       12.3   For information about pollution prevention that may be applicable to laboratory
             operations, consult "Less is Better: Guide to Minimizing Waste in Laboratories." 7
13.    WASTE MANAGEMENT

       13.1   The analytical procedures described in this method generate relatively small
             amounts of waste since only small amounts of reagents are used.  The matrices of
             concern are drinking water.  However, the Agency requires that waste
             management practices be conducted consistent with all applicable rules and
             regulations, and that the air, water, and land is protected by minimizing and
             controlling all releases from bench operations. Also, compliance is required with
             any sewage discharge permits and regulations, particularly the hazardous waste
             identification rules and land disposal restrictions.
14.     REFERENCES

       1.     Standard Methods for the Examination of Water and Wastewater.  21st Edition.
             American Public Health Association. Washington DC. 2005.

       2.     Safety in Academic Chemistry Laboratories. Vol  1. 7th Edition. American
             Chemical Society Publication; Committee on Chemical Safety, Washington DC,
             2003. (available for download at http://membership.acs.Org/C/CCS/pub  3.htm).

       3.     Chemical Safety Manual for Small Businesses. 3rd Edition. American Chemical
             Society, Committee on Chemical Safety, Washington DC, 2009. (available for
             download at http://membership.acs.Org/C/CCS/pub  5.htm).

       4.     Occupational Safety and Health Administration (OSHA), Hazard
             Communication. 29 CFR 1910.1200.

       5.     Occupational Safety and Health Administration (OSHA), Occupational Exposure
             to Hazardous Chemicals in Laboratories.  29 CFR 1910.1450.

       6.     Standard Test Method for Residual Chlorine in Water. ASTM D 1253-03.  ASTM
             International, West Conshohocken, PA. 2003.

       7.     Less is Better: Guide to Minimizing Waste in Laboratories.  American Chemical
             Society, Task Force on Laboratory Environment, Health,  & Safety, Washington
             DC, 2002. (available for download at
             http://membership. acs. org/C/CC S/pub 9. htm).
                                          16

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15.    TABLES AND FLOWCHARTS
Table 1.  Summary of Start-up QC for Grab Sample Methodology
Method
Reference
10.1.1.2
10.1.1.3
10.1.2.1
10.1.2.2
10.1.3
Requirement
Generate or
validate
calibration
curve
Verify
accuracy of
secondary
standards
Initial
Demonstration
of Capability
(IDC) -
Accuracy
Initial
Demonstration
of Capability
(IDC) -
Precision
Field Sampler
IDC
Specification
Analyze method blank & 3
calibration standards that span
concentration range (Lowest
standard < 0.2 mg/L or the
minimum required by primacy
agency.)
Analyze secondary standards on
each meter for which they will be
used.
Analyze method blank & 5
replicate independent reference
samples fortified at a
concentration near the drinking
water concentration
Calculate relative standard
deviation (RSD) for 5
independent reference sample
replicate analyses
Each sampler must successfully
complete 10.1.2.1 and 10. 1. 2.2
(IDC samples may be prepared by
laboratory personnel for analyses
by field samplers.)
Acceptance Criteria
Each standard is within
±15% of its expected
concentration when
compared to curve
Each secondary standard is
within ±10% of its expected
concentration
Method blank < %
concentration of lowest
calibration standard;
Average of 5 replicates is
within ±15% of expected
concentration
RSD < 15%

Table 2.  Summary of Start-up QC for On-line Chlorine Analyzer
  Method
 Reference
 Requirement
   Specification and Frequency
    Acceptance Criteria
 10.2.1
Verify or adjust
analyzer
calibration
Analyze grab sample & compare
to analyzer reading; Adjust
analyzer to agree with grab
sample measurement; Iterative
process until agreement is reached
Analyzer reading is within ±
0.1 mg/L or ± 15%
(whichever is larger) of grab
sample measurement
 10.2.2
Initial
Demonstration
of Capability
(IDC)
Compare analyzer measurement
to a grab sample analysis on a
daily basis for 14 consecutive
days (or business days)
Analyzer reading must be
within ± 0.1 mg/L or ± 15%
(whichever is larger) of the
grab sample measurement
for each data pair	
                                         17

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Table 3. Routine QC for Grab Sample Methodology
Method
Reference
11.1.1
11.1.2
Requirement
Routine
calibration
check
Secondary
standards
Specification and Frequency
Analyze a check standard:
• When calibration of the on-line
chlorine analyzer is adjusted
• At least quarterly
Recommended: analyze each day
grab sample method is used
(This is only applicable to
methods that use a
spectrophotometer/colorimeter.)
Acceptance Criteria
Standard is within ±15% of
its expected concentration
Each secondary standard is
within ±10% of its expected
concentration
Table 4. QC for On-line Chlorine Analyzer
Method
Reference
11.2
11.3
11.4
Requirement
Routine
calibration
check
Non-routine
calibration
check
Emergency
calibration
check
Specification and Frequency
Compare analyzer measurement
to a grab sample analysis:
• on a routine basis (at least once
each week)
• immediately after analyzer
calibration is adjusted
• one day after analyzer
calibration is adjusted
Compare analyzer measurement
to a grab sample analysis:
• after routine maintenance
• when analyzer drifts upward or
downward without explanation
(recommended)
If the analyzer indicates a large
(> 50%) unexpected change in
chlorine residual, compare
analyzer measurement to a grab
sample analysis as soon as
possible
Acceptance Criteria
Analyzer reading must be
within ± 0. 1 mg/L or ± 15%
(whichever is larger) of the
grab sample measurement
Analyzer reading must be
within ± 0. 1 mg/L or ± 15%
(whichever is larger) of the
grab sample measurement
Analyzer reading must be
within ± 0. 1 mg/L or ± 15%
(whichever is larger) of the
grab sample measurement
                                       18

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                 Flowchart 1.  Start-up Procedure for Grab Sample Method
                                    Select an approved grab sample method
                                    from tabular listing in regulation (e.g., DPD
                                       colorimetric, amperometric titration)
                                                 (Section 1.2)
                                     Calibrate or verify calibration for each
                                       spectrometer/colorimeter or titrator
                                         (Analyze a blank + 3 standards)
                                               (Section 10.1.1)
Determine source of problem & fix
                                         This shows that the
                                           meter/titrator is
                                              accurate.
                                                              Verify accuracy of secondary
                                                              standards on each colorimeter
                                                                   (Section 10.1.1.3)
                                    Initial demonstration of capability (IDC)
                                               for each sampler
                                    (Analyze a blank + 5 replicate independent
                                       reference samples) (Section 10.1.2)
                                    No
Is accuracy &
  precision
criterion met?
                                         This shows that the
                                         sampler can use the
                                          method properly.
                                                       Yes
                                     Ready to use grab sample method for
                                      verifying accuracy of on-line chlorine
                                                   analyzer
                                                       19

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                  Flowchart 2.  Start-up QC for On-line Chlorine Analyzer
                                   Install on-line chlorine analyzer
                                   & follow manufacturers' start-up
                                            procedures
                                     Verify analyzer calibration
                                     (Compare analyzer reading to
                                      result from a grab sample
                                             analysis)
If you must use this analyzer for
  compliance monitoring, then
 daily grab sample comparisons
       will be needed
                                                                         Adjust analyzer calibration
                                                                          according to manufacturers'
                                                                                instructions
                                   Analyzer Initial Demonstration
                                        of Capability (IDC)
                                   (Daily grab sample comparisons
                                           for 2 weeks)
   Identify problem & take
      corrective action
                                       Analyzer is ready for
                                      compliance monitoring
                                                 20

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Flowchart 3.  Routine QC for On-line Chlorine Analyzer
                       Verity analyzer calibration
                       (Compare analyzer reading to
                        result from a grab sample
                               analysis)
                                                          Continue under routine grab
                                                        sample schedule unless analyzer
                                                           shows unexpected change
                                                            (at least one grab sample
                                                                 each week)
Check for problems with
the analyzer
(follow manufacturers'
recommendations for
troubleshooting)


A second grab sample analysis
will rule out variability problems
in grab sample measurement
                       Adjust analyzer calibration
                         (follow manufacturers'
                             instructions)
                       Verify analyzer calibration
                       (Compare analyzer reading to
                        result from a grab sample
                               analysis)
                    Verify analyzer calibration after
                          one day of operation
                       (Compare analyzer reading to
                        result from a grab sample
                               analysis)
                                                          Check for problems with
                                                                the analyzer
                                                            (follow manufacturers'
                                                             recommendations for
                                                               troubleshooting)
Return to routine grab s
schedule
ample
                                  21

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                            METHOD 334.0 APPENDIX A

  OPTIONAL PROCESS FOR ESTABLISHING A SCHEDULE FOR ROUTINE GRAB
    SAMPLE COMPARISONS TO ON-LINE CHLORINE ANALYZER READINGS

A.     Historical data can be used to establish a routine schedule for comparing grab sample
       measurements to the results from the on-line chlorine analyzer.  The data must
       demonstrate that the grab sample measurements are frequent enough to detect problems
       with the analyzer within a reasonable period of time after the problems occur. The
       following protocol is presented as a conservative approach to developing a routine
       schedule when historical data are not available. The acceptance criterion that must be
       met in each step is that the on-line chlorine analyzer reading is within ±0.1 mg/L or ±
       15% (whichever is larger) of the grab sample measurement.  (Section  B provides a
       flowchart of this process.)

       A. 1   The data from the on-line analyzer IDC (See Section 10.2.2) can be used as the
             initial data set. If the on-line chlorine analyzer and grab  sample results meet the
             acceptance criteria over the 14 day period of the IDC, compare the concentration
             determined by the on-line chlorine analyzer with grab sample analyses collected
             every three days for 9 days.

       A.2   If the on-line chlorine analyzer continues to meet acceptance criteria over the
             above 9 day period, the grab sample interval can be extended to once every four
             days for 12 days.

       A.3   As long as the acceptance criterion is met, continue extending  the interval
             between grab samples using the same pattern as established in A.2 (i.e., once
             every 5 days for 15 days, once every 6 days for 18 days,  etc).  Collect a minimum
             of three grab samples each time the interval is extended by one day. The
             maximum time between grab samples must not exceed once every 7 days (i.e.,
             a weekly grab sample).

       A.4   When the on-line analyzer fails to meet the acceptance criteria, resolve the
             problem following the protocol in Section 11.2. After the analyzer/grab sample
             agreement has been reestablished, examine the data collected in steps A.2 to A.3
             to decide whether to continue extending the time between grab samples or to
             establish a schedule based on the existing data.  Continue extending the time
             intervals between grab samples beginning with the interval that was being used
             prior to when the on-line analyzer failed to meet the acceptance criteria.

       A.5   Establish the routine grab sample frequency at an interval which is no greater than
             one seventh of the average length of time between observed failures. The
             maximum time between grab samples must not exceed once every seven days.
                                          22

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B. Process for Establishing Frequency of Routine Grab Sample Comparisons to Analyzer Readings
Set grab sample
frequency at daily
j
\Yes
L
         i Find & resolve problem
         i Verify accuracy with a grab sample
         i Verify accuracy after 24 hrs with
          another grab sample
                                                 Adjust frequency
                                              Grab samples every fourth
                                                  day for 12 days
                                                                         i Find & resolve problem
                                                                         i Verify accuracy with a grab sample
                                                                         i Verify accuracy after 24 hrs with
                                                                          another grab sample
i
k
• Find & resolve problem
• Verify accuracy with a grab sample
• Verify accuracy after 24 hrs with
another grab sample
                                                 Adjust frequency
                                             Grab samples every fifth day
                                                    for 15 days
                                                 Adjust frequency
                                            Grab samples every sixth day
                                                    for 18 days
                                                                         i Find & resolve problem
                                                                         i Verify accuracy with a grab sample
                                                                         i Verify accuracy after 24 hrs with
                                                                          another grab sample
                                                 Adjust frequency
                                             Grab samples every seventh
                                                  day for 21 days
         i Find & resolve problem
         i Verify accuracy with a grab sample
         i Verify accuracy after 24 hrs with
          another grab sample
                                             Set grab sample frequency
                                                at every seventh day
                                                         23

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