Comparative study of direct immersion and headspace single drop microextraction techniques for BTEX determination in water samples using GC-FID

Abstract

In the present work the determination of benzene, toluene, ethylbenzene and o-xylene (BTEX) in environmental sample solutions using gas chromatography with flame ionisation detection (GC-FID) combined with three different sampling techniques, such as; direct single drop microextraction (DI-SDME), headspace single drop microextraction (HS-SDME) and ultrasonic assisted HS-SDME, were compared. In all of these techniques, for the determination of BTEX, the experimental parameters such as organic solvent effect, extraction time, agitation speed and salting effect were optimised. At their optimised conditions of operation the detection limits, times of extraction and precision for the three techniques are established. A detailed comparison of the analytical performance characteristics of these techniques for final GC-FID determination of BTEX in water samples was given. The technique provided a linear range of 50–20000 ng mL^–1 for DI-SDME and 10–20000 ng mL^–1 for HS-SDME methods, good repeatability (RSDs <4.72–7.74% for DI-SDME and 1.80–7.05% for HS-SDME (n = 5), good linearity (r ≥ 0.9978) and limits of detection (LODs) in the range of 0.006–10 ng mL⁻¹ for DI-SDME, 0.1–3 ng mL^–1 for HS-SDME methods (S/N = 3). Then the optimised techniques were also applied to real samples (river and waste waters) containing BTEX and similar precision (RSD < 8.2, n = 3) was obtained.

Keywords:

• single drop microextraction (SDME)
• headspace single drop microextraction (HS-SDME)
• BTEX
• water analysis
• GC-FID

Acknowledgement

The authors would like to acknowledge the Ferdowsi University of Mashhad, Iran, for supporting this work financially.