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Ionization enhancement in atmospheric pressure chemical ionization and suppression in electrospray ionization between target drugs and stable‐isotope‐labeled internal standards in quantitative liquid chromatography/tandem mass spectrometry
Author(s) -
Liang H. R.,
Foltz R. L.,
Meng M.,
Bennett P.
Publication year - 2003
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.1268
Subject(s) - chemistry , chromatography , electrospray ionization , direct electron ionization liquid chromatography–mass spectrometry interface , atmospheric pressure chemical ionization , chemical ionization , mass spectrometry , extractive electrospray ionization , ionization , tandem mass spectrometry , ambient ionization , electrospray , liquid chromatography–mass spectrometry , analytical chemistry (journal) , sample preparation in mass spectrometry , ion , organic chemistry
The phenomena of ionization suppression in electrospray ionization (ESI) and enhancement in atmospheric pressure chemical ionization (APCI) were investigated in selected‐ion monitoring and selected‐reaction monitoring modes for nine drugs and their corresponding stable‐isotope‐labeled internal standards (IS). The results showed that all investigated target drugs and their co‐eluting isotope‐labeled IS suppress each other's ionization responses in ESI. The factors affecting the extent of suppression in ESI were investigated, including structures and concentrations of drugs, matrix effects, and flow rate. In contrast to the ESI results, APCI caused seven of the nine investigated target drugs and their co‐eluting isotope‐labeled IS to enhance each other's ionization responses. The mutual ionization suppression or enhancement between drugs and their isotope‐labeled IS could possibly influence assay sensitivity, reproducibility, accuracy and linearity in quantitative liquid chromatography/mass spectrometry (LC/MS) and liquid chromatography/tandem mass spectrometry (LC/MS/MS). However, calibration curves were linear if an appropriate IS concentration was selected for a desired calibration range to keep the response factors constant. Copyright © 2003 John Wiley & Sons, Ltd.