Homogeneous liquid-phase microextraction followed by filtration-based phase separation coupled to high-performance liquid chromatography

A simple homogenous liquid-phase microextraction methodology applying octanoic acid as the extraction phase was introduced for determination of chlorobenzenes. In this approach, phase separation phenomenon occurred by changing pH of the solution. The extraction phase was isolated based on filtration of emulsion instead of centrifugation and it was introduced to the high-performance liquid chromatography instrument as an on-line procedure. This method was used for extraction and determination of five chlorobenzenes in different samples. Experimental design and response surface methodology were used for the optimization of various parameters influencing the extraction efficiency of the method. Under optimal conditions, chlorobenzenes were effectively extracted, and preconcentration factors of 255-294 were obtained. The calibration curves were investigated in the concentration range of 1-200 mu g/L and good linearity was achieved with coefficient of determinations better than 0.997. Limits of detection of 0.1 and 0.3 mu g/L and suitable precision with relative standard deviations better than 5.1% (n = 5) were attained. Finally, the proposed method was applied to determine the concentration of chlorobenzenes in different samples and acceptable recoveries were gained.