Acceptable PAO (Polyalphaolefin) for Filter Leak Testing

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 March 94 and December 96 FDA CGMP (Current Good Manufacturing Processes) release specified a distinct CAS# as a replacement for DOP (DEHP) – excerpt below:

The Chemical Abstracts Service (CAS) number which identifies this product was 68649‐12‐ 7. Other reported alternatives used in the industry include DOS (DEHS or Di‐2‐ethylhexyl sebacate) and Ondina Oil. However, no manufacturer has yet submitted all the necessary data to evaluate these alternatives.  As such, Emery 3004 PAO with the CAS number 68649‐12‐7 still remains an acceptable replacement for DOP.

CGMP Notes (Vol. 4, Number 4), December 1996

ATI’s position is that PAO-4 with a CAS # 68649‐12‐7 is acceptable by FDA definition.

Since the release of the aforementioned CGMP note, ATI has conducted testing of other 4 cSt PAO products, 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 either polydisperse Laskin III-A and thermal condensation generators, or near mono-disperse controlled nebulizers.

Please note, other polyalphaolefin products may be available; however 4 cSt PAO (PAO-4) is the only suitable DOP/DEHP (dioctylphthalate/Diethylhexylphthalate) aerosol reagent.

Please Note:  Varieties of PAO that have viscosity ratings other than 4 cSt might not generate aerosols having similar characteristics and MAY be potentially hazardous.