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Abstract
A multicommutation flow system for the spectrophotometric determination of hypochlorite in bleaching products is proposed. In this system, N,N-diethyl-p-phenylenediamine (DPD) reacts with hypochlorite, and the product was monitored at 515 nm. The analytical curve for hypochlorite was linear in the concentration range from 2.68 × 10−5 to 1.88 × 10−4 mol L−1 (2–14 mg L−1) with a detection limit of 6.84 × 10−6 mol L−1 (0.51 mg L−1). The sampling rate was 45 h−1, and a relative standard deviation of 1.4% (n = 10) was obtained. The recovery of this analyte ranged from 97.2% to 102.5%, and the results found using the proposed spectrophotometric multicommutated flow system agreed with the data obtained using a reference method (iodometric titration) at the 95% confidence level.
The authors acknowledge fellowships and the financial support from Brazilian agencies Fundaçào de Amparo à Pesquisa do Estado de São Paulo (FAPESP), Conselho Nacional de Desenvolvimento Cientifico e Tecnológico (CNPq), and Coordenação de Aperfeiçoamento de Pessoal de Nivel Superior (CAPES).