A novel miniaturized homogenous liquid-liquid solvent extraction-high performance liquid chromatographic-fluorescence method for determination of ultra traces of polycyclic aromatic hydrocarbons in sediment samples

摘要

A novel technique called miniaturized homogeneous liquid-liquid extraction (MHLLE) followed by high performance liquid chromatographic-fluorescence detection (HPLC-FL) was developed for the extraction and determination of some polycyclic aromatic hydrocarbons (PAHs) as model for analytical problem in sediment samples. The method is based on the rapid extraction of PAHs from a methanolic sample solution into 0.5mL n-hexane, as a solvent of lower density than water. After addition of water, the extracting solvent immediately forms a distinct water-immiscible phase at the top of the vial, which can be easily separated, evaporated and re-dissolved in 25μL of methanol and injected to the HPLC instrument. The parameters affecting the extraction process such as type and volume of organic extraction solvent, extraction time, and salt addition were investigated and the partition coefficient between methanol/water-n-hexane phases was evaluated and used to predict the extraction efficiency. Under optimal conditions, the limits of detection were estimated for the individual PAHs as 3S_b (three times of the standard deviation of baseline) of the measured chromatogram, are in the range of 0.003-0.04ngg~(-1) for sediment samples. The relative recoveries of PAHs at spiking levels of 1.0ngg~(-1) for sediment samples were in the range of 81-92%. The method was also applied to a corresponding standard references materials (IAEA-408) successfully. The proposed method is very fast, simple, and sensitive without any need for stirring and centrifugation.