I believe alcohol will pull the triprolidine along with the pseudo. Also if you base it, the triprolidine will convert to oil along with the pseudo, and of course, will precipitate along with the pseudo upon gassing.
I haven't done this myself because I always make sure to get pills with pseudo as the only active ingredient, but I think if you did one or the other, you can get those two amines on their own and then figure out how to seperate them. Someone mentioned in another post about the "smurf dope" was a different color because it contained antihistamines. It was suggested that chlorinated break cleaner aka trichloroethylene could work possibly? This will dissolve either one or the other and you can filter out the solid.
I spent a good amount of time looking up these different solubility properties for different ingredients of pill compositions both active and inactive. These two are particularly difficult to seperate from each other, I can't seem to find much information. If you are unable to find the right solvents to isolate them, I am thinking if you converted them to base oil and then did a fractional distillation, that would probably be the best and most simple way to go...
2.5mg is pretty insignificant as far as impurity or contamination in any event. 40 pills = 2.4g of PSE and ~100mg of triprolidine, so, if left in with the product it may be noticible, but I doubt it will be a deal-breaker...
I hope one of the experts can throw their two cents in.... I would love a solution, or any suggestions to solve this dilemma myself.. to be able to confront simillar problems.
Good luck,
o7