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Matrix‐assisted laser desorption/ionisation time‐of‐flight/thin layer chromatography/mass spectrometry—a rapid method for impurity testing
Author(s) -
Mowthorpe Siew,
Clench Malcolm R.,
Cricelius Anna,
Richards Don S.,
Parr Vic,
Tetler Lee W.
Publication year - 1999
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/(sici)1097-0231(19990228)13:4<264::aid-rcm460>3.0.co;2-m
Subject(s) - chemistry , mass spectrometry , chromatography , analyte , analytical chemistry (journal) , matrix (chemical analysis) , mass spectrum , sample preparation in mass spectrometry , thin layer chromatography , impurity , electrospray ionization , organic chemistry
Thin layer chromatography/matrix‐assisted laser desorption/ionisation mass spectrometry (TLC/MALDI‐MS) has been previously used to obtain mass spectra from a variety of compounds, principally peptides. For pharmaceutical compounds, which are often of relatively low molecular weight, it is important that any matrix materials employed do not interfere with the mass spectra obtained. The key step to successful TLC/MALDI‐MS is hence the preparation of the TLC plate prior to mass spectrometry. Crucial to this is the deposition of matrix material into the plate to promote co‐crystallisation with the analyte. In this work we have examined the literature methods for plate preparation and developed two new approaches. The first involves brushing the TLC plate with a supersaturated solution of matrix and the second involves electrospraying the TLC plate with a matrix solution. Data are presented from the direct analysis of tetracycline and its impurities. Using the electrospray method the limit of detection for tetracycline is 1 ng from a TLC plate. A commercial MALDI‐TOF mass spectrometer has been modified to allow the acquisition of chromatographic data from TLC plates. Chromatograms from replicate spots of 100 and 1 µg of tetracycline are shown. Copyright © 1999 John Wiley & Sons, Ltd.