EN
Tests For: Free, Combined and Total Chlorine in Water
Test Range: 0–5 mg/L (Standard Range), 0–10 mg/L (Extended Range)
Reagent Chemistry Used: DPD
Basis of Test Method: Standard Method 4500-Cl-G, US EPA Ref. 330.5, ISO7393-2:2000-04
| Test Type | Method Detection Limit (MDL)* (mg/L) | Limit of Quantification (LOQ)** (mg/L) |
| Standard Range (Tablet) | 0.01 | 0.01 |
| Standard Range (Liquid) | 0.01 | 0.01 |
| Extended Range (Tablet) | 0.01 | 0.05 |
This Palintest chlorine test uses the DPD method developed by Dr A T Palin and now internationally recognised as the standard method of testing for chlorine and other disinfectant residuals.
Free chlorine reacts with diethyl-p-phenylene diamine (DPD) in buffered solution to produce a pink coloration. The intensity of the colour is proportional to the free chlorine concentration. Subsequent addition of excess potassium iodide induces a further reaction with any combined chlorine present. The colour intensity is now proportional to the total chlorine concentration; the increase in intensity repre¬sents the combined chlorine concentration. In this way it is possible to differentiate between free and combined chlorine present in the sample. The colour intensities are measured using a Palintest Photometer.
Chlorine and chlorine-release compounds are widely used for the disinfection of drinking water and swimming pools, for the control of micro-biological growth in cooling water, and in many other water treatment systems. Accurate measurement of the chlorine residual is an essential aspect of the control of these chlorination processes.
It is recommended that if any shock treatment compounds are known to have been used in the treatment of the water to be tested, that a DPD Oxystop tablet be included in the test procedure. The DPD Oxystop tablet is added after measurement for free chlorine but before the DPD No 3 tablet. It prevents the reaction between shock treatment chemicals and potassium iodide which would give a positive response.
Chlorine and chlorine-release compounds are widely used for the disinfection of drinking water and swimming pools, for the control of micro-biological growth in cooling water, and in many other water treatment systems. Accurate measurement of the chlorine residual is an essential aspect of the control of these chlorination processes.
The chlorine level can be expressed in terms of the free chlorine, combined chlorine or total chlorine residuals. For most of the applications measurement of the free chlorine residual is the most important. The Palintest DPD chlorine method provides a simple means of measuring free, combined, and total chlorine residuals over the range 0–5 mg/l.
