Problem with determination of Diclazuril

[psyclones]

Working with method of the European Commission for diclazuril in feed (COMMISSION REGULATION (EC) No 152/2009 of 27 January 2009) , the next step without changing anything, but obviously somewhere lose the active ingredient , because finally I have neither and diclazuril peak or the internal standard . Or washing is lost or remains in the cartridge . Someone confronted you with this problem.

[tom jupille]

The trick with that kind of problem is to work backwards from known results.

Start by running standards with no sample prep. If the peaks look OK, that verifies that the column and mobile phase are correct. If not, then you must address that issue.

If the column and mobile phase are OK, run a matrix blank through your workup procedure and then spike it just before injecting. If it does not look OK, then you have some interference in the matrix. If it *does* look OK, then start with another matrix blank and spike it just before the last step in the workup. Keep repeating that process, working your way up the chain until you find the step (or steps) that cause the problem and then address the chemistry of that step.