Salt-assisted liquid-liquid microextraction for the determination of iodine in table salt by high-performance liquid chromatography-diode array detection

2-lodosobenzoate and N,N-dimethylaniline have been used at pH 6.4 for selective conversion of iodide to 4-iodo-N,N-dimethylaniline which was extracted with ethanol, when the phase separation occurred by addition of ammonium sulphate, a process called salt-assisted liquid-liquid microextraction (SALLME), and analysed by high-performance liquid chromatography-diode array detection. Iodate was reduced to iodide before derivatisation. The method has been optimised for extracting solvent, salt for phase separation, and reaction time. A linear calibration was obtained for 10 mu g-10 mg L-1 of iodide with correlation coefficient of 0.9989 and limit of detection of 3.7 mu g L-1. The SALLME produced 280-fold enrichment of the derivative. The commercial iodised table salt samples have been found highly inhomogeneous; the RSD in analysis of different aliquots of the same sample ranged 18.0-78.1%. The average recovery of spiked iodide to real samples was 98.4% with an average RSD of 7.9% (range 5.2-12.4%). (C) 2010 Elsevier Ltd. All rights reserved.