Isotopic pattern and accurate mass determination in urine drug screening by liquid chromatography/time-of-flight mass spectrometry
| Type: | Application |
Scientific Paper |
Food & Environmental, Gen. Pharma & Chemistry |
| Number: | Technology |
10.1002/rcm.2429 |
OTOF |
| Year | Products |
2006 |
micrOTOF, SigmaFit, AccuScreen, TargetAnalysis |
| Author | |
Suvi Ojanperä 1 *, Anna Pelander 1, Matthias Pelzing 2, Ilmari Krebs 2, Erkki Vuori 1, Ilkka Ojanperä 1 |
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| Reference | |
Rapid Communications in Mass Spectrometry Volume 20, Issue 7 , Pages 1161 - 1167 |
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Abstract |
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An efficient method was developed for toxicological drug screening in urine by liquid chromatography coupled with electrospray ionization time-of-flight mass spectrometry. The method relies on a large target database of exact monoisotopic masses representing the elemental formulae of reference drugs and their metabolites. Mass spectral identification is based on matching measured accurate mass and isotopic pattern (SigmaFitTM) of a sample component with those in the database. Data post-processing software was developed for automated reporting of findings in an easily interpretable form. The mean and median of SigmaFitTM for true-positive findings were 0.0066 and 0.0051, respectively. The mean and median of mass error absolute values for true-positive findings were 2.51 and 2.17 ppm, respectively, corresponding to 0.65 and 0.60 mTh. For routine screening practice, a SigmaFitTM tolerance of 0.03 and a mass tolerance of 10 ppm were chosen. Ion abundance differences from urine extracts did not affect the accuracy of the automatically acquired SigmaFitTM or mass values. The results show that isotopic pattern matching by SigmaFitTM is a powerful means of identification in addition to accurate mass measurement. |
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