Spectrophotometric Assay for Hypochlorite/Hypochlorous Acid Using Tris(2-carboxyethyl)phosphine

✍ Scribed by Joan Han; Teh-Ching Chu; Grace Han; John Browne; Irene Brown; Peter Han

• Publisher: Elsevier Science
• Year: 1998
• Tongue: English
• Weight: 84 KB
• Volume: 58
• Category: Article
• ISSN: 0026-265X
• DOI: 10.1006/mchj.1997.1542

✦ Synopsis

A simple spectrophotometric method for quantitative determination of hypochlorite (OCl 0 ) or hypochlorous acid (HOCl) is described. The OCl 0 or HOCl sample is first incubated with an excess amount of tris(2-carboxyethyl)phosphine (TCEP). The concentration of the residual TCEP is then measured as the amount of 2-nitro-5-thiobenzoate produced after reaction with 5,5dithiobis(2-nitrobenzoic acid). The concentration of OCl 0 or HOCl is equivalent to the amount of decrease in the concentration of TCEP because one molecule of TCEP is rapidly and irreversibly oxidized to TCEP oxide by one molecule of OCl 0 or HOCl. This method is more sensitive and convenient than the standard procedure of NaOCl assay which involves reaction with potassium iodide followed by titration of the liberated triiodide with thiosulfate.