SOP: Detection of Residual Chlorine in Water by the Chlorotex Test

GIFSQ — Global Institute for Food Safety & Quality

Principle

The chlorotex reagent produces a coloured compound in the presence of chlorine, the colour deepening with increasing chlorine concentration. The colour produced is compared with the tints given on the colour chart supplied with the set.

Reagents

a. Chlorotex reagent (manufactured by the British Drug Houses Ltd.).

Procedure

Add 50 ml of the water under test rapidly to 5 ml of the reagent

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Mix and allow to stand for 1 min

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Compare the colour produced with the tints given on the colour chart supplied with the set

Note: in the presence of 0.1 to 0.2 mg per litre of chlorine, a pink colour develops which changes to red at 0.5 mg/litre, purple at 0.6 mg/litre and blue at 1 mg/litre; green and brown colours occur when the chlorine content exceeds 1 mg/litre.