Determination of benzene, aniline and nitrobenzene in workplace air: a comparison of active and passive sampling

Abstract There have been numerous investigations on methods for assessing the relative performance of pumped and diffusive sampling techniques for the determination of airborne contaminants. Diffusive sampling is a convenient and cost-effective analytical tool for measuring exposure to chemical hazards in air and has been available as a replacement for pumped sampling for around 20 years. In spite of the considerable amount of work put into their evaluation, diffusive samplers have only been partially successful in replacing pumps. Generally, evaluation studies on diffusive samplers have been concentrated primarily on their accuracy at high concentrations, neglecting the vital aspect of their applicability at lower concentrations (below mg m 3 ) in the field. The present evaluation demonstrates that a Perkin-Elmer-type sampling tube, filled with Tenax TA and operated diffusively, provides a means of sampling that is sufficiently sensitive to measure benzene, aniline and nitrobenzene at concentrations as low as 0.10 mg m 3 . This method gives precise and accurate results that are well within the National Institute for Occupational Safety and Health (NIOSH) acceptability criteria of ±25% accuracy. No correlation is observed between active and diffusive sampling at concentration levels below 0.01 mg m 3 . Retention volumes, thermal desorption recoveries, sampling efficiencies, diffusive uptake rates and concentration effect on sampling performance were investigated. There are no previous reports, on determination of aniline and nitrobenzene in air by diffusive sampling and thermal desorption.