• 2025-07-07

Available chlorine

The core indicator for measuring the oxidizing ability of chlorinated disinfectants

Available chlorine refers to the active chlorine content that chlorine-containing compounds (such as bleaching powder, hypochlorite, etc.) can still maintain after acidification. This parameter mainly reflects the effective concentration of hypochlorous acid (HOCl) and dissolved chlorine gas, and does not include combined chlorine combined with amines or organic matter.

There are often technical misunderstandings about "available chlorine" in the industry:

Some practitioners simply equate it with "chlorine with oxidizing ability"

In fact, its definition focuses more on the measured value of standardized detection methods

The current main detection methods include:

O-toluidine colorimetry (OTO method)

N,N-diethyl-p-phenylenediamine spectrophotometry (DPD method)

Note: When iodide or bromide is present in water, the measurement results of the above methods will include the interference values of these halogens.