Any clue on the reasons for low recovery % in drug tablets? I got 64% and 68% for PCM in a drug sample analyzed on RP-HPLC using ACN: 50 mM phosphate buffer (60:40) on a C-18 YMC HPLC column.
Hi, hope you had already sorted out this issue.
If you have not, you might want to clarify some of the following points before others can help answer your question.
- Did you use internal standard (IS) for your analyses? If you did, are their recovery % as low as your drug analyte (PCM)?
- what extraction method did you use for your sample prep? protein precipitation? liquid-liquid extraction? solid phase extraction? Different extraction methods give different recovery %, and SPE gives lowest recovery in general (which needs to be corrected by IS).
- How do your peaks look? Are they good, sharp peak? or do they come in broad multiple peaks? Integration can only be good when the peaks are acceptable. Wrong integration can easily lead to inaccurate computation of recovery %.
Last one, but probably a stupid question, were your internal standards (if you used them) added BEFORE the extraction step? I heard of some cases where IS was added AFTER the extraction step, which defeat the purpose of IS for drug concentration analysis.
Hope this helps.
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