Due to toxicity issues, only one suitable Polyalphaolefin, PAO-4, a 4 centistokes (4 cSt) synthetic aliphatic hydrocarbon, may be used in Filter Leak Testing.
The original 1996 FDA CGMP (Current Good Manufacturing Processes) release specified a distinct CAS# as a replacement for DOP (DEHP) – excerpt below:
ATI’s position is that PAO-4 with a CAS # 68649‐12‐7 is acceptable by FDA definition. However, since the release of the aforementioned CGMP note, ATI has conducted testing of another 4 cSt PAO, CAS# of 68037‐01‐4, and found that there is no measurable differences in the particle size distribution, standard deviation or leakage measurements obtained, using polydisperse Laskin III-A and thermal condensation generators, as well as a multiple near mono-disperse controlled nebulizers.
Please note, other polyalphaolefin products may be available; however 4 cSt PAO or PAO-4 is the only suitable DOP/DEHP (dioctylphthalate/Diethylhexylphthalate) aerosol reagent.