PALINTEST LTD: Palintest ChloroSense: Chlorine, free and total, in drinking water by Amperometry
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Official Method Name
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Measurement of free and total chlorine in drinking water by Palintest ChloroSense (Amperometry) |
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Current Revision
| August 10, 2009 (Revision 1.0) |
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Media
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WATER |
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Instrumentation
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Amperometer |
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Method Subcategory
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Inorganic |
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Method Source
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Citation
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Brich, S.W., Sutherland, J., and Lendrem, T., 2009, Measurement of free and total chlorine in drinking water by Palintest ChloroSense. |
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Brief Method Summary
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Chlorine may be present as free residual chlorine and as combined chlorine. The two forms may co-exist and can be determined together as total available chlorine. Free chlorine is present in the sample as hypochlorous acid, hypochlorite ion and undissociated chlorine. Combined chlorine may be present as monochloramine, dichloramine and nitrogen trichloride. Free available chlorine reacts with 3,3',5,5' tetramethylbenzidine (TMB) and the oxidized TMB is electrochemically reduced at the surface of the free chlorine electrode. Free available chlorine and combined chlorine react with potassium iodide (KI) to liberate iodine. The iodine can be reduced electrochemically at the surface of the total chlorine electrode. The current that flows in each case is proportional to the amount of free available chlorine or total available chlorine. The current is converted to mg Cl/L by reference to calibration parameters stored in the instrument software. |
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Scope and Application
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This method is for the determination of free available and total chlorine including hypochlorous acid, hypochlorite ion and undissociated chlorine in drinking water. |
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Applicable Concentration Range
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The application range is 0.02 - 10 mg Cl/L free chlorine and 0.05 - 75 mg/L Cl/L total chlorine. |
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Interferences
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Other disinfectant residuals such as bromine, chlorine dioxide, iodine, ozone and peroxide may react with TMB and KI or directly with the electrode surface and cause a positive interference. No interferences have been encountered with the chemical species found naturally in drinking water or added as treatment chemicals. |
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Quality Control Requirements
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Quality Control requirements include the Initial Demonstration of Capability and ongoing QC requirements that must be met when preparing and analyzing field samples. See section 9.0 from more details. |
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Sample Handling
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Collect samples in chlorine-demand free amber glass containers, filling the container headspace free. Avoid exposure to sunlight or agitation during sampling. |
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Maximum Holding Time
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Analyze immediately after sample collection, as chlorine in aqueous solution is not stable. A sample may be collected directly in the instrument sample container. |
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Relative Cost
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Unknown |
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Sample Preparation Methods
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