Poor recovery of neat standards vs. extracted controls GCMS

[kvirkler]

Does anyone have any insight as to why we would be getting poor/no recovery of a neat opiate standard (TMS derivatives) on GCMS compared to when we extract a positive blood control spiked with the same standard? Both are the same concentration. Does the presence of the matrix really make a difference? We are using Agilent Ultra Inert deactivated liners, splitless, single taper, with glass wool. It seems like we should be getting higher recovery for the neat standard.

[KM-USA]

Add additional derivatizing agent to both, and re-inject. If the standard has a little more water in it, might be using up all the derivatization chemical.

[kvirkler]

Thank you - this is good advice. I also just noticed that the standard and control are dried down at different temperatures in the Turbovap prior to derivatization, so we are looking into that as well.