Determination of Isocyanates in Workplace Atmosphere by HPLC

Abstract

Determination of diisocyanates in the laboratories of the Authorities of Public Health was described and verified. Air samples collected in the breathing zone of workers exposed to diisocyanates were analyzed in an automotive industry. Diisocyanates (2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4�-methylenediphenyl isocyanate, and 1,6-hexamethylene diisocyanate) were measured by HPLC and the validation characteristics were determined. Diisocyanate exposure was monitored in the workplace atmosphere of 25 workers. Air samples from the breathing zone were collected and analyzed by HPLC after extraction. The results were compared to the occupational exposure limit. Reliability of the method was confirmed by validation characteristics for the diisocyanates. The repeatability of the method ranged from 2.98 to 4.51%, the calculated relative standard uncertainty was 11 � 12% for the parameters, and the recovery was between 99 and 103%. The low LOD and LOQ ensured the determination of the diisocyanates in the harmful concentration. Monitoring of diisocyanate exposure was performed on four different workplaces. The results showed that 2,4-toluene diisocyanate and 2,6-toluene diisocyanate were present in the concentration range from 6.3 to 13.2 �g m-3. The 1,6-hexamethylene diisocyanate was found in all cases below the limit of detection and the 4,4�-methylenediphenyl isocyanate was found only at two workplaces (between 8.3 and 44.8 �g m-3). The HPLC method was found to be appropriate for the determination of diisocyanates. Applying the method for the determination of diisocyanate exposure in four different workplaces, which produce car accessories, showed that the diisocyanate level did not exceed the occupational exposure limit set for average exposure.