A green method for the determination of hypochlorite in bleaching products based on its native absorbance

A new, green method for the determination of hypochloride in bleaching products is here presented. The method, based on a flow injection system and measurement of the native absorbance of hypochlorite at 292 nm, allows the determination of hypochlorite in the range 0.07–0.42 g Cl2 l−1. In order to achieve high selectivity a mini-column containing cobalt oxide, which effectively catalyses hypochlorite decomposition to chloride and oxygen, was inserted in the flow system. The difference in absorbance of samples no circulated and circulated through the mini-column was selected as analytical signal; thus, the method only requires 20 mg of solid, reusable catalyst, and a NaOH solution of pH 10.4; providing a sample throughput of 12 samples h−1 in triplicate injection. Its usefulness for analysis of bleaching products is demonstrated.