Trace analysis of methyl tert-butyl ether in water samples using new ultrasound-assisted dispersive liquid-liquid microextraction and gas chromatography-flame ionization detection

Abstract

In this study, simple and efficient ultrasound-assisted dispersive liquid-liquid microextraction combined with gas chromatography (GC) was developed for the preconcentration and determination of methyl-tert-butyl ether (MTBE) in water samples. One hundred microliters of benzyl alcohol was injected slowly into 10 mL home-designed centrifuge glass vial containing an aqueous sample with 30% (w/v) of NaCl that was located inside the ultrasonic water bath. The formed emulsion was centrifuged and 2 μL of separated benzyl alcohol was injected into a gas chromatographic system equipped with a flame ionization detector (GC-FID) for analysis. Several factors influencing the extraction efficiency such as the nature and volume of organic solvent, extraction temperature, ionic strength and centrifugation times were investigated and optimized. Using optimum extraction conditions a detection limit of 0.05 μg L-1 and a good linearity (r2 = 0.998) in a calibration range of 0.1-500 μg L-1 were achieved. This proposed method was successfully applied to the analysis of MTBE in tap, well and a ground water sample contaminated by leaking gasoline from an underground storage tank (LUST) in a gasoline service station.