| Autor: |
Müller C; Institute of Legal Medicine, Klinikum der Albert-Ludwigs-Universität Freiburg, Albertstrasse 9, D-79104, Freiburg, Germany., Schäfer P, Störtzel M, Vogt S, Weinmann W |
| Jazyk: |
angličtina |
| Zdroj: |
Journal of chromatography. B, Analytical technologies in the biomedical and life sciences [J Chromatogr B Analyt Technol Biomed Life Sci] 2002 Jun 15; Vol. 773 (1), pp. 47-52. |
| DOI: |
10.1016/s1570-0232(02)00142-3 |
| Abstrakt: |
Ion suppression effects during electrospray-ionsation mass spectrometry (ESI-MS) caused by different sample preparation procedures for serum were investigated. This topic is of importance for systematic toxicological analysis for which LC-ESI-MS has been developed with transport-region collision-induced dissociation (ECI-CID) and mass spectra library searching. With continuous postcolumn infusion of two test compounds-codeine and glafenine-the ion suppression effects of extracted biological matrix obtained after a standard liquid-liquid extraction, a mixed-mode solid-phase extraction (SPE) method, a protein precipitation method and a combination of precipitation with polymer-based mixed-mode SPE have been investigated. Extracted ion chromatograms of codeine ([M+H](+), m/z 300) and glafenine ([M-H](-), m/z 371) were used for monitoring ion suppression. Severe ion suppression effects for codeine and glafenine were detected in positive and in negative ionisation modes, respectively, in the LC-front peak after serum clean-up with SPE (acid/neutral fraction) and protein precipitation as well as with protein precipitation combined with SPE. Less ion suppression of codeine in positive mode was found with liquid-liquid extraction of serum samples. No ion suppression was detected with the second fraction of the mixed-mode SPE (using RP-C(8) and cation-exchange phase) in both ionisation modes. All suppression effects were caused by polar and unretained matrix components, which were present after extraction and/or protein precipitation. However, no specific ion suppression was seen after elution of the polar LC-front throughout the whole gradient. It could be demonstrated, that ion suppression is not generally present at any retention time when using reversed-phase HPLC with rather long gradient programs, but may play an important role in case of high-throughput LC-MS analysis, when the analyte is not separated from the LC-front, or in flow injection analysis without chromatographic separation. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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