Study on determination of time-weighted average concentration for benzene, toluene and xylenes in air

  Objective   To establish a gas chromatogr aphic method with carbon disulfide desor ption for benzene, toluene and xylenes in time-weighted average(TWA)concentration in the workplace air.

  Methods   Solvents such as benzene, to luene and xylenes were sampled with charcoal tube.Solvent desorption with carbon disulfide and analysis by GC(FID)were performed.

  Results   Linear limits of the methods: benzene 210 to 50 μg/ml, toluene 3.1 to 100μg/ml and xylenes 8.5 to 600 μg/ml.The coefficient of correlation ranged from 0.999 5 to 0.999 9.Limit of detection of the solvents above were 210, 311 and 815 μg/ml.The breakthrough capacities of 100 mg charcoal for the solvents above were 33.3, 29.1 and 27.2 mg respectively.Samples could be storaged stablity at least 7 days under normal conditions.

  Conclusion   These methods were corresponding to the Chinese guidelines of the method for determination of toxic substances in workplace air and confirmed suitable to determine the selected solvents in TWA concentration in workplace air.