Application of cold-induced aggregation microextraction as a fast, simple, and organic solvent-free method for the separation and preconcentration of Se(IV) in rice and various water samples

The developed method is based on cold-induced aggregation microextraction of Se(IV) using the 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid as an extractant followed by spectrophotometry determination. The extraction of Se(IV) was performed in the presence of dithizone as the complexing agent. In this method, a very small amount of 1-butyl-3-methylimidazolium hexafluorophosphate was added to the sample solution containing Se-dithizone complex. Then, the solution was kept in a thermostated bath at 50 A degrees C for 4 min. Subsequently, the solution was cooled in an ice bath and a cloudy solution was formed. After centrifuging, the extractant phase was analyzed using a spectrophotometric detection method. Some important parameters that might affect the extraction efficiency were optimized (HCl, 0.6 mol L-1; dithizone, 4.0 x 10(-6) mol L-1; ionic liquid, 100 mu L). Under the optimum conditions, good linear relationship, sensitivity, and reproducibility were obtained. The limit of detection (LOD) (3S(b)/m) was 1.5 mu g L-1, and the relative standard deviation (RSD) was 1.2 % for 30 mu g L-1 of Se(IV). The linear range was obtained in the range of 5-60 mu g L-1. It was satisfactory to analyze rice and various water samples.