Simultaneous determination of trichloroethylene, perchloroethylene and trichloroacetic acid in human urine using solid-phase microextraction fibre coated with single-walled carbon nanotubes

Abstract

A reliable and sensitive method for simultaneous determination of perchloroethylene (PCE), trichloroethylene (TCE), and trichloroacetic acid (TCA) in human urine by gas chromatography-mass spectrometry (GC/MS) is described after extraction and preconcentration by a new solid-phase microextraction (SPME) adsorbent. The potential of single-walled carbon nanotubes (SWCNTs) as SPME adsorbent for the pre-concentration of environmental pollutants has been investigated in recent years. This work was carried out to investigate the feasibility of SWCNTs as a headspace SPME adsorbent for the determination of chloroethylenes in human urine. SWCNTs were attached onto a stainless steel wire through an organic binder. Potential factors affecting the extraction efficiency, including extraction time, extraction temperature, desorption time, desorption temperature, and salinity were optimized. The developed method showed good performance. For PCE and TCE, calibration curves were linear (r ²≥ 0.994) over the concentration ranges from 15 to 8000 ng L⁻¹ and the limit of detection (LOD) at signal-to-noise (S/N) ratio of 3 was 5 ng L⁻¹. The analytical procedure also involves derivatization of TCA with dimethyl sulfate, before headspace sampling. For TCA the linear range and LOD were 45-8000 (r ²≥ 0.992) and 15 ng L⁻¹, respectively. In addition, a comparative study between the SWCNT and a commercial carboxen/polydimethylsiloxane (CAR/PDMS) SPME fibre for the determination of chloroethylenes in human urine was carried out. SWCNT fibre showed higher extraction capacity, better thermal stability (over 350°C) and longer life span (over 200 times) than the commercial CAR/PDMS fibre. The developed method was successfully applied to determine chloroethylenes in human urine samples. As the results indicated, the mean concentrations of TCE, PCE and TCA in exposed workers (dry-cleaning industry workers) were significantly greater than that of control group.

Keywords:

• SPME adsorbent
• SPME coating
• perchloroethylene
• trichloroethylene
• trichloroacetic acid
• single-walled carbon nanotubes
• solid-phase microextraction
• GC/MS, HS-SPME

Acknowledgements

This research has been supported by Tehran University of Medical Sciences (TUMS) and Health Services grant (Project No. 88-01-46-8305). Hereby, the cooperation of the university and also the Center for Environmental Research (CER) is highly appreciated.