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Direct quantification of alkaloid mixtures by electrospray ionization mass spectrometry
Author(s) -
Selby D. S.,
Guilhaus M.,
Murby J.,
Wells R. J.
Publication year - 1998
Publication title -
journal of mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 1076-5174
DOI - 10.1002/(sici)1096-9888(199812)33:12<1232::aid-jms741>3.0.co;2-x
Subject(s) - chemistry , ionization , electrospray ionization , analytical chemistry (journal) , mass spectrometry , alkaloid , analyte , chromatography , fragmentation (computing) , ion , electrospray , stereochemistry , organic chemistry , computer science , operating system
For two‐component mixtures, Kebarle and Tang observed thatthe ionization efficiency (i.e., yield of ions per unitconcentration) depends strongly on the concentration and natureof other ionizable species and weakly on total concentration ofionized species. In this work, the model used by Kebarle and Tang wasextended to several components. The extended model was tested in astudy to determine whether analysis by extrospray ionization could beused as a fast method to screen and quantify five alkaloids present inillicit heroin samples. The samples analysed included authenticstandards. Solutions of the samples were infused directly into theelectrospray ion source of a Finnigan TSQ 700 instrument. Theresulting spectra contained a peak for each species at M+1. Nosignificant fragmentation was observed for any of the five analytes.It was found that the ‘ionization efficiencies’(assumed constants in the Kebarle and Tang model) showed adependence on total alkaloid concentration. In a blind study of 16sample solutions, each containing five alkaloids (one used as aninternal standard), the error distributions for the 64 resultsobtained were skewed when calculated on the basis of a simpleextension of the Kebarle model. When the variation of ionizationefficiency with total alkaloid concentration was taken into account,the error distribution was normal. Errors were characterized(relative to total alkaloid mass) by an average error of‐0.24%, a standard deviation of errors of 2.48%,a maximum error of 6.84% and a minimum error of‐9.51%. © 1998 John Wiley & Sons,Ltd.