An approach for estimating workplace exposure to o-toluidine, aniline, and nitrobenzene

A comprehensive approach to estimating worker exposure to o-toluidine, aniline, and nitrobenzene using a combination of surface wipe, dermal badge, and air samples is described. Desorption of each sample was accomplished with ethanol followed by analyses using capillary gas chromatography with flame ionization detection. Analyte recovery was maximized when the gauze wipes and dermal badges were immediately desorbed in ethanol after sample collection. Sample collection of the airborne analytes was improved over previous solid sorbent samples by using a sampling train consisting of an acid-treated glass fiber filter in series with a large capacity silica gel tube (520/260 mg). The greatest recoveries of aniline and o-toluidine were from the acid-treated glass fiber filters and nitrobenzene from the large capacity silica gel sorbent tubes. The limit of detection for each analyte (1 micrograms) was approximately 10 times more sensitive than reported in previous National Institute for Occupational Safety and Health methods. Analyte recoveries for air samples were greatest under conditions of moderate relative humidity (53%), moderate sample volumes (< 50 L), and low flow rates (0.2 L/min). The overall relative standard deviation of the analytical method was 4.3%.