GENERATION OF HEXAHYDROPHTHALIC ANHYDRIDE ATMOSPHERES IN A CONTROLLEDHUMAN-USE TEST CHAMBER

A method for generating controlled atmospheres of hexahydrophthalic an hydride (HHPA) in an 8 m3 exposure chamber was developed. The permeati on principle was used for gaseous HHPA generation. HHPA concentration was monitored by sampling on XAD-2 tubes and by a Fourier-transform in frared (FTIR) spectrometer using the partial least-square quantitative method. The repeatability of the FTIR was 5%, the reproducibility 12% , and the limit of detection 10 mug/m3.A bubbler method determined the sum of HHPA and HHP acid by using gas chromatography/mass spectrometr y detection after derivatization with methanol/ boron trifluoride. The precision of the work-up procedure was 3% and the recovery was 94% at 300 ng sampled amount of HHPA. The limit of detection was 10 ng HHPA. The variation in the permeation rate was 3% over 3 days. Different co ncentrations in the exposure chamber were generated by changing the te mperature of the permeation tubes. The generated HHPA concentration ra nge, at human exposure, was 3-90 mug/m3. The concentration at one temp erature was reproducible even after major changes in the temperature. The coefficient of variation (CV) of six samples from different places in the breathing zone was 3%. The variation in the concentration, dur ing an 8-hour human exposure at 10 mug/m3, was 3%. Time-weighted avera ges (8 hour) for human exposures of 10 mug/m3 (CV = 15%; n = 6); 37 mu g/m3 (CV = 5%; n = 5); and 81 mug/m3 (CV = 6 %; n = 9) were obtained a t intended concentrations of 10 mug/m3, 40 mug.m3, and 80 mug/m3. The loss of HHPA in the exposure chamber was 54% (CV = 17%). HHP acid conc entration in air was negligible compared to the HHPA concentration.