Solid Phase Microextraction as a Short-Term Sampling Technique for BTEX Occupational Exposure

Abstract

Solid phase microextraction (SPME) has been widely used for many years in various applications, such as environmental and water samples, food and fragrance analysis, or biological fluids. The aim of this study was to suggest the SPME method as an alternative to conventional techniques used in the evaluation of worker exposure to benzene, toluene, ethylbenzene, and xylene (BTEX). Polymethylsiloxane-carboxen (PDMS/CAR) showed as the most effective stationary phase material for sorbing BTEX among other materials (polyacrylate, PDMS, PDMS/divinylbenzene, Carbowax/divinylbenzene). Various experimental conditions were studied to apply SPME to BTEX quantitation in field situations. The uptake rate of the selected fiber (75 μm PDMS/CAR) was determined for each analyte at various concentrations, relative humidities, and airflow velocities from static (calm air) to dynamic (> 200 cm/s) conditions. The SPME method also was compared with the National Institute of Occupational Safety and Health method 1501. Unlike the latter, the SPME approach fulfills the new requirement for the threshold limit value-short term exposure limit (TLV-STEL) of 2.5 ppm for benzene (8 mg/m³).

Keywords:

• air analysis
• BTEX
• solid phase microextraction
• SPME
• volatile organic compounds

Notes

^A Benzene conc. levels were 892, 544, and 301 μg/m³.

^B Toluene conc. levels were 568, 346, and 192 μg/m³.

^C Ethylbenzene conc. levels were 782, 477, and 264 μg/m³.

^D p-Xylene conc. levels were 1466, 894, and 495 μg/m³.

^E o-Xylene conc. levels were 541, 330, and 182 μg/m³.

^A Macropore ≥ 500Å, Mesopore = 20–500Å, Micropore = 2–20Å.