PA could stand for lots of things. In the present contest there is a case for suggesting it stands for “pro analysi”. Many chemicals are sold as puriss (or purim) p.a. which means that they have a certificate of purity. If a reaction does not work, checking the purity of compounds is one possibility
In chemistry, what do the letters “PA” stand for?
We have talked about this before; I’ll search out the old threads. 
Well, I can’t find any. Others better at ferreting out this stuff will no doubt be along.
ah I didnt spot it was a classic. The original discussion may be hard to find though
I thought of pKa for a second, but that’s not exactly in the amateur level.
Hmm, and howdy.
I do agree with the initial answer to this question, i.e. that the one posing the query just mixed up PA and pH. For me, this is based upon having to check the PA frequently (well, P-aitch…could sound mighty close) and you would have to if one was concocting something that land someone in jail.
But when it comes to odd acronyms, short-cuts and abbrv.s etc, chemistry is second to none. I mean, why write ethylenediaminetetraacetic acid, when you can just write EDTA? And of course, why call it dioxyribonucleic acid when you can just call it DNA?
My guess is LAH, which is truly gnarly, extremely hard to get your mitts on, and basically blows on contact with really humid air, or baring that, just plain 'ole water. But it would do the job that this gent seemed to be going towards…a powerful oxidizer.
But still, pH does make more sense. Just felt like mouthing off a bit.
Word.
L
I believe it stands for proton affinity, which is related to pH. Good resource is here
Kevin
Having just gotten done dealing out a few grams of this I can tell you it is not quite that bad. It is a bit shock sensitive. Also, it is not at all an oxidizer it is a serious reducer.
I agree with Cecil on this. If they were checking the PA regularly, they were probably actually checking the pH. This is a very common thing to do even for amatuer chemists.