Short Duration Needle Trap Sampling with Gas Chromatography Analysis to Determine Nearly Instantaneous Concentrations of Selected Organic Vapor Contaminants

Abstract

Needle trap device samplers were used for rapid (60 s) quantitative sampling of short-term exposure limit (STEL) and peak exposure standard concentrations using a manually operated pump to collect small volume (10 mL) gas phase samples containing methylene chloride, benzene, toluene, and tetrachloroethylene vapors. Solventless introduction of chemical samples for gas chromatography analysis with flame ionization detection yielded linear results (R² > 0.99) for vapor standard mixtures of the four target analytes ranging from 10% to 200% of their respective nominal STEL or peak exposure standard concentrations. Needle trap samplers showed ≥86% recovery (as GC-FID peak area responses) following 14-day storage at room temperature compared to the same samplers analyzed immediately, with better recovery values observed with shorter storage (≥95% at room temperature for seven days, except for methylene chloride) or with storage at 4°C. Calibration for quantitation of concentrations of benzene, toluene, and tetrachloroethylene was shown to be possible with the use of an internal standard to account for injector discrimination between the solventless NTD approach and injections of target analytes in carbon disulfide. Due to the simple sampling method (no field calibration and battery-free pumping) and the avoidance of solvent dilution, a needle trap sampling approach could simplify sample collection and analysis to chromatographically determine nearly instantaneous (1 min) exposure concentrations.

Keywords:

• needle trap device
• gas chromatography
• flame ionization detector
• air sampling
• ceiling
• short term exposure limit

ACKNOWLEDGMENTS

This work received financial support from the U.S. Army Center for Environmental Health Research and material support from the U.S. Department of Labor, OSHA Salt Lake Technical Center. The views presented are those of the authors, and do not represent those of their respective organizations. This document is not a standard or regulation. It creates no new legal obligations and alters no existing obligations created by OSHA standards or the Occupational Safety and Health Act. It may contain recommendations that are advisory in nature, informational in content, and are intended to support the provision of safe and healthful workplaces. This article is not subject to US copyright law.