Air sampling and analytical procedures for benzidine, 3,3'-dichlorobenzidine and their salts.

The purpose of the study was the development of new air-sampling and analytical procedures for benzidine, 3,3'-dichlorobenzidine and their salts. Air is drawn through a glass-fiber filter followed by a bed of silica gel to collect these substances as either particles or vapors. The compounds are extracted from the sampler and analyzed by HPLC with sensitivities in the range of 3 micrograms/m3 for 48-L air samples. The methods were evaluated in the laboratory with test aerosol atomospheres and found to be unaffected by temperature or humidity of the sampled environment. Tests of precision, sample stability and separation from interferants indicate that the method should provide reliable results for personal monitoring procedures.