Generation of hexahydrophthalic anhydride atmospheres in a controlled human-use test chamber

A method for generating controlled atmospheres of hexahydrophthalic anhydride (HHPA) in an 8 m3 exposure chamber was developed. The permeation principle was used for gaseous HHPA generation. HHPA concentration was monitored by sampling on XAD-2 tubes and by a Fourier-transform infrared (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 micrograms/m3. A bubbler method determined the sum of HHPA and HHP acid by using gas chromatography/mass spectrometry 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 concentrations in the exposure chamber were generated by changing the temperature of the permeation tubes. The generated HHPA concentration range, at human exposure, was 3-90 micrograms/m3. The concentration at one temperature 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, during an 8-hour human exposure at 10 micrograms/m3, was 3%. Time-weighted averages (8 hour) for human exposures of 10 micrograms/m3 (CV = 15%; n = 6); 37 micrograms/m3 (CV = 5%; n = 5); and 81 micrograms/m3 (CV = 6%; n = 9) were obtained at intended concentrations of 10 micrograms/m3, 40 micrograms/m3, and 80 micrograms/m3. The loss of HHPA in the exposure chamber was 54% (CV = 17%).(ABSTRACT TRUNCATED AT 250 WORDS)