Indirect cloud point extraction and spectrophotometric determination of nitrite in water and meat products

A new indirect micelle mediated cloud point extraction method has been developed for sensitive determination of trace amounts of nitrite by spectrophotometry. The method is based on the well known oxidation-reduction reaction of nitrite by iodide ion in acidic medium and cloud point extraction of I-3(-) formed from aqueous solution using Triton X-100. The extracted surfactant rich phase is diluted with water and its absorbance is measured at 365 nm. The effects of different operating parameters such as concentration of surfactant, KI concentration, temperature, incubation time and acid concentration on the cloud point extraction were studied in details and a set of optimum conditions was obtained. A linear calibration graph was obtained in the range of 8-120 ng mL(-1) The limit of detection (LOD) based on three times the standard deviation of the blank (3S(b)) was 6.0 ng mL(-1) (n = 10) and the relative standard deviation (RSD) for determination of 60 ng mL(-1) of nitrite was 3.40% (n = 10). The method was applied to the determination of nitrite in meat products and water samples. (C) 2012 Elsevier By. All rights reserved.