Use of switchable solvent liquid phase microextraction for determination of petroleum pollutants in water samples by gas chromatography–mass spectrometry

In this study switchable solvent liquid phase microextraction (SSLPME) followed by GC-MS detection has been developed for preconcentration and determination of total petroleum hydrocarbons (TPHs) in water samples. The extraction technique makes use of 100 μL of a water-immiscible solvent (dipropylamine) that can be solubilized in the aqueous phase in 1:1 ratio using HCl as a reagent. Afterwards, phases separation is induced by the addition of sodium hydroxide. Optimization of the variables affecting this method was carried out in order to achieve the best extraction efficiency. The optimized conditions included: volume of the sample 5 mL, volume of extraction solvent 100 μL, and pH of sample: 12.0. Under the optimum experimental conditions, good limits of detection (0.3–1.21 µg L−1), linearities (R2 > 0.996), and repeatability of extraction (RSDs below 5.6%, n = 5) were obtained. Finally, the developed method was successfully applied to the determination of the target analytes in different types of natural water samples and acceptable recoveries (>84%) were obtained.