Evaluation of Tenax TA for the determination of chlorobenzene and chloronitrobenzenes in air using capillary gas chromatography and thermal desorption

Abstract A method for the determination of chloronitrobenzenes (CNBs) and chlorobenzene (CB) in air was developed. CNBs and CB were sampled on Tenax TA sampling tubes, thermally desorbed and analysed by capillary gas chromatography (cGC) with flame ionization detection. The sampling efficiency was found to be independent of flow-rate (25 and 50 ml/min) and relative humidity (30–90%) generated in the laboratory. Recovery studies on Tenax TA (20–35, 35–60 and 60–80 mesh) in the concentration range 0.041–8.212 mg/ml were conducted using cGC coupled with an automatic thermal desorption system (ATD-50). Nearly quantitative recoveries were obtained at all levels of concentrations. Further, it was observed that flow-rates and relative humidity had no effect on the adsorption and thermal desorption efficiency of CNBs and CB when present as a mixture in workplace air. No loss of sample was observed up to 30 days of storage at room temperature. With this method, a time-weighted average concentration of less than 0.04 mg/m 3 could be determined in an 8-h sampling period with a precision of 1.4–12% for the whole method.