sample in pH=7.4 buffer with salts

Discussions about sample preparation: extraction, cleanup, derivatization, etc.

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I've been working on method development for a molecule and the sample matrix is pH=7.4 buffer with salts. The QC samples have been behaving very strange. All the QCL samples recovery is around 80%. But the QCH samples recovery is sometimes 93%, sometimes around 65%. I've tested for several times and I just cannot control it.
I tested the stock solution from which I prep the QC samples and it's right on spot. I don't know what is happening I've been stuck here for a long time.

I just started doing method development and I really appreciate it if any one can give me some help.
More detailed information about your prep process would be very helpful. And I assume by QCL and QCH you refer to two concentration levels?
I'm really sorry that I forgot to reply (3 months... i'm so sorry). Just let you know I figured out the problem shortly after I posted the question. The drug has a propensity to attach to the tube and that causes the problem.
3 posts Page 1 of 1

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