Liquid phase microextraction-ion exchange-high performance thin layer chromatography for the preconcentration,...

Liquid phase microextraction combined with ion-exchange-high performance thin layer chromatography has been developed for analysis of four plasticizers in aqueous samples. After their preconcentration by liquid phase microextraction, fast separation on thin layers of inorganic ion-exchanger stannic silicate has been developed using a mixture of toluene + ethyl acetate (10:1, v/v) as mobile phase. Consequently, densitometric quantitative determination of the plasticizers has been made at λ = 280 nm in reflection-absorption mode by Camag TLC scanner-3. The effects of type and volume of extraction solvent, stirring rate, extraction time, and ionic strength in the microextraction method have been also evaluated and optimized. The results show that the proposed method provides enhanced accuracy, linear range, LOD, and LOQ, and is very effective for analyzing the target compounds in water samples. Under the optimized conditions, preconcentration factor of 149-279 and extraction efficiency of 31-59% have been obtained. Repeatability (5.67-7.26%) and intermediate precision (6.21-8.17%) were in acceptable range. The relative recovery obtained for each analyte in different water samples was higher than 82.3% at three fortification levels with RSD <7.9%.