TY - JOUR
T1 - Identification and elimination of ion suppression in the quantitative analysis of sirolimus in human blood by LC/ESI-MS/MS
AU - Mano, Nariyasu
AU - Nozawa, Marina
AU - Sato, Mayumi
AU - Mori, Masaru
AU - Yamaguchi, Hiroaki
AU - Kanda, Katsuhiro
AU - Nogami, Makoto
AU - Goto, Junichi
AU - Shimada, Miki
N1 - Funding Information:
The authors are grateful for financial support from Hitachi High-Technologies Corporation .
Copyright:
Copyright 2011 Elsevier B.V., All rights reserved.
PY - 2011/4/15
Y1 - 2011/4/15
N2 - Ion suppression can negatively affect the performance characteristics of LC/ESI-MS/MS based methods, and we wished to identify sources of ion suppression in an assay for quantitating sirolimus in human whole blood. We first compared the peak areas of sirolimus and ascomycin added to human blood samples treated with and without extraction using octadecyl silyl (ODS)-silica gel after protein precipitation, and we found that water-soluble compounds cause the ion suppression for both drugs. Post-column infusion studies indicated that compounds retained in the sample after ODS extraction and protein precipitation caused ion suppression. MS analysis of these compounds suggested they were hydroxyl group-possessing phosphocholines, and this was confirmed using purified lysophosphatidylcholine variants. Therefore, we included a HybridSPE treatment step after the ODS extraction into the preanalytical workflow to remove phosphocholines, and this successfully eliminated the observed ion suppression for determining sirolimus concentration in human whole blood by LC/ESI-MS/MS. Sirolimus is a highly lipophilic molecule, and this study demonstrates the impact that preanalytical extraction and purification steps can have on a laboratory's ability to accurately detect and quantitate this and other lipophilic drugs.
AB - Ion suppression can negatively affect the performance characteristics of LC/ESI-MS/MS based methods, and we wished to identify sources of ion suppression in an assay for quantitating sirolimus in human whole blood. We first compared the peak areas of sirolimus and ascomycin added to human blood samples treated with and without extraction using octadecyl silyl (ODS)-silica gel after protein precipitation, and we found that water-soluble compounds cause the ion suppression for both drugs. Post-column infusion studies indicated that compounds retained in the sample after ODS extraction and protein precipitation caused ion suppression. MS analysis of these compounds suggested they were hydroxyl group-possessing phosphocholines, and this was confirmed using purified lysophosphatidylcholine variants. Therefore, we included a HybridSPE treatment step after the ODS extraction into the preanalytical workflow to remove phosphocholines, and this successfully eliminated the observed ion suppression for determining sirolimus concentration in human whole blood by LC/ESI-MS/MS. Sirolimus is a highly lipophilic molecule, and this study demonstrates the impact that preanalytical extraction and purification steps can have on a laboratory's ability to accurately detect and quantitate this and other lipophilic drugs.
KW - Electrospray ionization
KW - Ion suppression
KW - Mass spectrometry
KW - Phospholipids
KW - Sirolimus
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U2 - 10.1016/j.jchromb.2011.03.011
DO - 10.1016/j.jchromb.2011.03.011
M3 - Article
C2 - 21435955
AN - SCOPUS:79953302837
SN - 1570-0232
VL - 879
SP - 968
EP - 974
JO - Journal of Chromatography B: Analytical Technologies in the Biomedical and Life Sciences
JF - Journal of Chromatography B: Analytical Technologies in the Biomedical and Life Sciences
IS - 13-14
ER -