A Comparison of Two Diffusive Samplers for the Collection of Styrene, α-Methylstyrene, and o-Chlorostyrene Vapors

Abstract

Styrene is a frequently encountered hazardous chemical in industry. Traditional methods of workplace air sampling involve the collection of vapors on a solid sorbent sampling tube, followed by laboratory desorption and analysis. The most common sorbent used is activated coconut shell charcoal, which exhibits poor desorption efficiencies at low styrene loadings. An alternative treated charcoal sorbent requires a more complex analytical procedure. In this study a diffusive sampler was validated for styrene according to a modified version of a protocol developed by the National Institute for Occupational Safety and Health. Two versions of the sampler were validated simultaneously, each having a different sorbent substrate. Both samplers passed the requirements of the validation procedure, including tests for desorption efficiency, uptake rate and capacity, reverse diffusion, storage stability, temperature effects, and a factorial study of concentration, sampling time, humidity, interferences, wind velocity, and sampler orientation, and their interactions. In total, 198 575-002 and 175 575-003 samplers were used in the full validation protocol. Both samplers were also tested for critical sampling parameters (desorption efficiency, uptake rate, and storage stability) according to the guidelines of the bi-level theory of sampler validation for the homologues α-methylstyrene and o-chlorostyrene. Sixty-four samplers of each type were used in the tests on α-methylstyrene, and 72 samplers of each type were used in the tests on o-chlorostyrene. While both samplers were shown to perform well, differences resulting from the use of different sorbents can be used to select the most appropriate sampler for a specific application. The uptake rates of the samplers for styrene, α-methylstyrene, and o-chlorostyrene are 13.7, 12.6, and 9.8 ml/min, respectively.