Does anybody have "any hands" on the determination of sulfadiazine and trimethoprim in feeds.
We have tried several extraction procedures to get these products from pelleted feeds but the recovery is not good in comparison with the non-pelleted feeds.

Are you grinding the pellets first? You may wish to address your question to someone at a U.S. state feed laboratory. Email me details of your problems, and I will try to forward your question.

Try to look up the Veterinary British Pharmacoepia. It should be one of the monographs in there. You can also try to mill it down using a coffee blender or ball mill then extracted with your sample solvent or try the sample solvent described in the USP monograph for Sulfadiazine and Trimethoprim Tablets.

I understand that your problem is that you can get the Sulfadiazine out of the mash but not out of the pellets. Is that right? Have you considered the binder ingredients? Spike the mash with some of the binder and see if that is the problem. The recovery of some drugs is hampered by bentonite that is either in the soybean meal or in the binder, even thought it isn't supposed to be there. Treatment with an aliquot of water for a few minutes will sometimes free the drug from the binder.

There is an old and good extraction procedure for separation of sulfa drugs and trimethoprim :
First, extraction of sulfa into NaOH 0.1N (extraction with NaOH/Chloroform) and the second, extraction of trimethoprim into acetic acid 6% from chloroform.
Try to quantify the above by HPLC using MP from monograph of Sulfadiazine in USP 23 and RP-Phenyl column.

Good luck.

I need to separate a 11 sulfa drugs a ppm levels and I have some problems to do that. Somebody can halp me?
Thanks