Hach Method 10260

Determination of Chlorinated Oxidants (Free and Total) in Water Using Disposable Planar 

Reagent-filled Cuvettes and Mesofluidic Channel Colorimetry

Revision 1.0

April 2013

1. Scope and Application

1.1 This method covers the determination of chlorinated oxidants in water using DPD 

chemistry in a disposable reagent-filled cuvette with mesofluidic channel colorimetry.

 

1.2 For this method, chlorinated oxidants are defined as the aqueous species that include free 

chlorine (Cl2, HOCl, and OCl-

), monochloramine, and total chlorine (monochloramine, 

dichloramine, and trichloramine).

1.3 The applicable analytical measurement range of this method is 0.12 mg/L to 4.6 mg/L as 

Cl2.

1.4 The performance of this method is equally effective to the USEPA reference methods of 

SM 4500-Cl G, EPA Method 330.5, and Hach Methods 8021 and 8167 and may be used 

for USEPA drinking water and wastewater regulatory reporting programs.

2. Summary of Method

2.1 This is a colorimetric disposable planar DPD reagent-filled cuvette version of the EPA 

Reference DPD Method 330.5, Standard Method 4500-Cl G, and Hach Methods 8021 

and 8167. A mesofluidic pump system is used to draw a water sample through the 

cuvette, where the sample is mixed with the appropriate reagents, and then moved to the 

optical channel where chlorine is measured at a wavelength between 490 to 530 nm.

3. Definitions

3.1 Calibration Check Standard (CC): An aqueous calibration standard containing the method 

analyte that is analyzed periodically to verify the accuracy of the existing calibration. 

3.2 Initial demonstration of capability (IDC): Replicate reference samples are analyzed to 

demonstrate the ability to obtain acceptable precision and accuracy. An IDC is performed 

the first time this method is used by each operator. 

3.3 Laboratory reagent blank (LRB): An aliquot of reagent water or other blank matrix that is 

treated as a sample including exposure to all glassware, equipment, solvents, and reagents 

that are used with other samples. The LRB is used to determine if method analytes or 

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other interferences are present in the laboratory environment, the reagents or the 

apparatus. 

3.4 Linear calibration range (LCR): The concentration range over which the instrument 

response is linear. 

3.5 Material safety data sheet (MSDS): Written information provided for the chemical 

reagents concerning a chemical’s toxicity health hazards, physical properties, fire, and 

reactivity data including storage, spill and handling precautions. 

3.6 Minimum Reporting Level (MRL): The lowest level at which the entire analytical system 

gives a reproducible signal that meets the method quality objectives. It is never lower 

than the concentration of the lowest calibration check (CC) standard. 

3.7 Quality control sample (QCS): A solution of method analyte of known concentration. 

The QCS is obtained from a source external to the laboratory or is prepared from 

standards obtained from a different source than the calibration standards. The purpose is 

to check laboratory performance using test materials that have been prepared 

independently from the normal calibration process.

3.8 Reagent water: Water demonstrated to be free from the method analyte and interfering 

substances

4. Interferences

4.1 As with all DPD methods for the measurement of chlorine, this method is equally subject 

to the same interferences of oxidized forms of iron and manganese.

4.2 No other interferences have been encountered with chemical species found naturally in 

drinking water or added as treatment chemicals.

5. Safety

5.1 The toxicity or carcinogenicity of each reagent used in this method has not been precisely 

determined; however, each chemical should be treated as a potential health hazard. 

Exposure to these chemicals should be reduced to the lowest possible level. It is 

suggested that the laboratory perform personal hygiene monitoring of each analyst using 

this method and that the results of this monitoring be made available to the analyst.

5.2 This method does not address all safety issues associated with its use. The laboratory is 

responsible for maintaining a safe work environment and a current awareness file of 

OSHA regulations regarding the safe handling of any chemicals specified in this method. 

A reference file of material safety data sheets (MSDSs) should be available to all 

personnel involved in these analyses. Additional information on laboratory safety can be 

found in Sections 16.2 and 16.3.

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6. Equipment

6.1 Sample containers (plastic or glass) free from chlorine oxidants and chlorine demand.

6.2 Colorimetric Pump/Meter System – Hach Company Mesofluidic Pump/Meter designed 

for Hach Planar DPD Reagent Filled Cuvettes (PFRC)

6.3 Disposable DPD Reagent Filled Cuvettes – Hach Company Chlorine PRFC strips. 

7. Reagents and Standards

7.1 Reagent Water – Purified water (typically either deionized or distilled). Reagent water 

can be purchased from a scientific supply company, if it is not available on site. If a 

chlorine demand is present, suggested procedures for preparing chlorine demand-free 

water are included in ASTM D 1253-03 and Standard Method 4500-Cl ).

7.2 Chlorine Standard Solution – Hach Company Catalog Number 1426820, 50 – 75 mg/L as 

Cl2, or equivalent.

8. Sample Collection, Preservation, and Storage

8.1 Collect samples in chlorine-demand free amber glass or plastic containers, filling the 

container to headspace free. Avoid agitation during sampling. Analyze within 15 minutes

of sample collection, as chlorine in aqueous solution is not stable.

9. Quality Control

9.1 Quality Control (QC) requirements include the Initial Demonstration of Capability and 

ongoing QC requirements that must be met when preparing and analyzing field samples. 

This section describes each QC parameter, its required frequency, and the performance 

criteria that must be met in order to meet EPA quality objectives. These QC requirements 

are considered the minimum acceptable QC criteria. Laboratories are encouraged to 

institute additional QC practices to meet their specific needs.

9.2 INITIAL DEMONSTRATION OF CAPABILITY (IDC) – The IDC must be successfully 

performed prior to analyzing any field samples. Prior to conducting the IDC, the analyst 

must meet the calibration requirements outlined in Section 10. Requirements for the 

initial demonstration of laboratory capability are described in the following sections.

9.2.1 DEMONSTRATION OF LOW SYSTEM BACKGROUND – Analyze a LRB 

after processing through all sample collection steps outlined in Section 8.1. The 

method blank concentration must be ≤ 1⁄3 the MRL.

9.2.2 INITIAL DEMONSTRATION OF ACCURACY – Prepare and analyze five 

independent reference samples at the same concentration. The concentration of the 

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samples should be at or below the mid range of the calibration curve. Calculate the 

average chlorine concentration for the five analyses. The average concentration 

for the five replicates must be within ± 15% of the expected value.

9.2.3 INITIAL DEMONSTRATION OF PRECISION – Using the same set of replicate 

data generated for Section 9.2.2 calculate the standard deviation and relative 

standard deviation (RSD) of the replicate values. The RSD is calculated using the 

equation %100×=XSRSD where S is the standard deviation for the replicate 

values, and X is the average value for the replicates. The RSD of the results of the 

replicate analyses must be ≤15%. 

9.3 ONGOING QC REQUIREMENTS – This section describes the ongoing QC criteria that 

must be followed when processing and analyzing field samples. 

9.3.1 DEMONSTRATION OF LOW SYSTEM BACKGROUND – Analyze a LRB 

with each analytical batch. The LRB should be processed through all sample 

collection steps outlined in Section 8.1. The method blank concentration must be 

≤ 1⁄3 the MRL. 

9.3.2 CONTINUING CALIBRATION CHECK – Analyze a CCC with each analytical 

batch. Prepare an aqueous calibration check standard at a concentration near the 

expected concentration of the water samples. Over time, vary the calibration check

standard concentration. The grab sample measured concentration of the calibration 

check standard must be within ± 15% of the expected value. If this criterion is not 

met, then the analyst must identify and resolve the problem.

9.4 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. 

9.4.1 QUALITY CONTROL SAMPLE (QCS) – Analysis of a sample from an 

external source (different from the calibration standards) provides an 

independent check of the calibration of the method. It is recommended 

semiannually or any time a new calibration curve is validated.

9.4.2 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 by the provider for each study. 

10. Initial Calibration Check and Calibration Verification

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10.1 Initial Calibration Check

10.1.1 Prepare a set of aqueous calibration check standards bracketing the range of the 

method. The lowest concentration calibration standard should be 0.20 mg/L Cl22. The 

highest standard should be 4.0 mg/L Cl2. 

10.1.2 Analyze the calibration standards according to the manufactures instrument 

instructions and the procedures in Section 11 of this method.

10.1.3 Compare the results of each measured concentration to that of the expected value. 

Each measured calibration verification point must be within ± 15% of its expected value.

10.1.3.1 If the measured value is outside the required ± 15%, prepare a new calibration 

verification standard and analyze.

10.1.3.2 If the new calibration verification standard is outside the required ± 15%, the 

factory installed calibration must be updated following the manufacturer’s instructions. 

Otherwise, send the chlorine meter to the manufacturer for repair or updating.

10.2 Calibration Verification

10.2.1 Prepare an aqueous calibration verification standard at 2.0 mg/L Cl2.

10.2.2 Analyze the calibration verification standard according to the manufactures 

instrument instructions and the procedures in Section 11 of this method.

10.2.3 Compare the result of the measured concentration to that of the expected value of 

2.0 mg/L Cl2. The measured calibration verification point must be within ± 15% of its 

expected value.

10.2.3.1 If the measured value is outside the required ± 15%, prepare a new calibration 

verification standard and analyze.

10.2.3.2 If the new calibration verification standard is outside the required ± 15% limit, 

repeat steps in the Initial Calibration Check Section 10.1.

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11. Procedure

11.1 Press and hold the power button on the meter until the title screen is displayed. 

11.2 When the meter passes all internal functional checks on start up, and the user has verified 

the optical performance the screen prompts the user to insert a PRFC.

11.3 Insert a chlorine-PRFC strip into the meter slot. Make sure to push the PRFC all the way 

into the slot and there is tactile feedback that the PRFC has interfaced with the pump. The 

meter will recognize the barcode on the PRFC and will display the parameter on the 

display.

11.4 Rinse the sample container 2-3 times and then fill the sample container to the line. 

11.5 Dip the PRFC into the sample and wait for a beep to acknowledge that the system has 

pulled the sample into the PRFC. The system uses a conductivity detector to determine 

when the PRFCs have been dipped into the water. Withdraw the PRFC from the sample 

and the test will automatically start. Once the test is finished the results will be stored 

and displayed on the screen. Remove the PRFC out of the instrument and dispose of in 

accordance with waste management procedures in Section 15 of this method.

12. Data Analysis and Reporting

12.1 The result of the sample measurement is displayed on the meter. No other calculation is 

required unless the sample was diluted prior to analysis and measurement.

12.2 If the sample was diluted prior to analysis and measurement, multiply the answer by the 

appropriate dilution factor: 

Total Volume

Dilution Factor = _____________

Sample Volume

where: 

Sample Volume = Aliquot of sample taken for dilution (mL) 

Total Volume = Volume to which sample volume is diluted (mL) 

Corrected Concentration = Observed concentration x dilution factor 

12.3 Report results in milligrams chlorine per liter (mg/L Cl2).

12.4 Report results to two significant figures from 0.12 to 4.60 mg/L Cl2.

13. Method Performance

13.1 Using the Hach PRFCs, three different laboratories reported that the MDL of replicate 

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observations (n =21) of a calibration standard containing ~0.2 mg/L Cl2 was 0.019 mg/L 

Free Cl2 and 0.025 mg/L Total Cl2 respectively. 

13.2 With multiple batches of PRFCs, the relative standard deviation of sets of observations (n 

= 21) of a calibration standard containing ~2.0 mg/L Cl2 was 2.30% for Free Cl2 and 

2.88% for Total Cl2.

14. Pollution Prevention

14.1 Dispose of PRFC strips according to the waste management requirements in Section 15 

of this method.

14.2 Standards should be prepared in volumes consistent with laboratory use to minimize the 

volume of expired standards to be disposed.

15. Waste Management

15.1 It is the laboratory’s responsibility to comply with all federal, state, and local regulations 

governing waste management, particularly the hazardous waste identification rules and 

land disposal restrictions, and to protect the air, water, and land by minimizing and 

controlling all releases from fume hoods and bench operations. Compliance with all 

sewage discharge permits and regulations is also required.

15.2 Excess reagents, samples and method process wastes should be characterized and 

disposed of in an acceptable manner. The MSDS sheet gives details of product 

composition and may be consulted for guidance on waste disposal.

15.3 For further information on waste management, consult “The Water Management Manual 

for Laboratory Personnel”, and “Less is Better: Laboratory Chemical Management for 

Waste Reduction”, both available from the American Chemical Society’s Department of 

Government Relations and Science Policy, 1155 16th Street N.W., Washington DC, 

20036.

16. References

16.1 “Carcinogens-Working With Carcinogens”, Department of Health, Education, and 

Welfare, Public Health Service, Center for Disease Control, National Institute for 

Occupational Safety and Health, Publication No. 77-206, August 1977.

16.2 “OSHA Safety and Health Standards, General Industry”, (29 CFR 1910), Occupational 

Safety and Health Administration, OSHA 2206 (Revised, January 1976). 

16.3 “Safety in Academic Chemistry Laboratories”, American Chemical Society, Committee 

on Chemical Safety, 3rd Edition, 1979. 

16.4 Standard Test Method for Residual Chlorine in Water, ASTM D1253-08 

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16.5 Standard Method 4500-Cl G, Standard Methods for the Examination of water and 

Wastewater 

17. Acceptance Criteria for Performance Tests

17.1 Acceptance Criterion Section Limit (%) 

17.1.1 Quantitation Range

Lower range of quantitation – 1.2 mg/L Cl2

Upper range of quantitation – 4.6 mg/L Cl2

17.1.2 Initial accuracy and precision 

Accuracy= ±15% 

Precision=15% 

17.1.3 Continuing calibration Check 

Accuracy=±15% 

17.1.4 Calibration verification 

Accuracy=±15% 

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