Selenium analysis in water samples by dispersive liquid-liquid microextraction based on piazselenol formation and GC-ECD

The application of the recently introduced dispersive liquid-liquid microextraction (DLLME) for the separation and determination of an inorganic selenite [Se(IV)] derivative by means of a gas chromatography-electron-capture detection system has been studied. The selenium derivative was extracted with the DLLME technique using a mixture of ethanol (disperser solvent) and chlorobenzene (extraction solvent). The influences of the various analytical parameters on the derivatization reaction and microextraction procedure have been evaluated and optimized. Under the optimum conditions, an enrichment factor of 122 was obtained for only 5.00 mL of the water sample. The calibration graph was linear in the range of 0.015-10 mu g L-1 with a detection limit of 0.005 mu g L-1. The relative standard deviation for ten replicate measurements of 2 mu g L-1 of selenium was 4.1%. The method was applied to the determination of selenium in environmental surface water samples with satisfactory recovery.