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The following message was posted to: PharmPK
I have spent a lot of time trying to minimize the effects of matrix effects
in the analysis of basic drugs in plasma. The major matrix interferences
in samples analyzed by protein precipitation are phospholipids and
lysophospholipid. I developed a method to employ one ion in MRM LCMS
analyses that detects all the high-level lysophospolipids and
phospholipids. I then used these to minimize the analysis time while still
separating the basic drugs from these lipids. The basic useful parameters
were flow, solvent composition, and temperature.
I also evaluated the effects on accuracy, precision, peak shape, retention
time, column back pressure, etc when these lipids were not eluted from the
I was surprise to find that the signal for these lipids become
"steady-state" in concentration. Also they began to elute with the analyte
after many injections. After they became steady-state, and the analyses
were not severely compromised.
I would be interested in others observations/comments:
see "Simple Method to Monitor Lysophospholipids and Phospholipids During
LC-MS Method Development via In-Source CID"
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Copyright 1995-2010 David W. A. Bourne (email@example.com)