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Different quantitation approaches for xenobiotics in human urine samples by liquid chromatography/electrospray tandem mass spectrometry
Author(s) -
Sancho Juan V.,
Pozo Oscar J.,
López Francisco J.,
Hernández Félix
Publication year - 2002
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.617
Subject(s) - chemistry , chromatography , analyte , electrospray , liquid chromatography–mass spectrometry , mass spectrometry , tandem mass spectrometry , sample preparation , urine , detection limit , electrospray ionization , biochemistry
The potential of liquid chromatography combined with tandem mass spectrometry (LC/MS/MS) for the determination of pesticide metabolites in human urine at the sub‐ppb level is explored. Metabolites from two organophosphorous pesticides, 4‐nitrophenol (from parathion and parathion‐methyl) and 3‐methyl‐4‐nitrophenol (from fenitrothion), are taken as model analytes to conduct this study. After direct injection of the urine sample (10 µL), different approaches were evaluated in order to achieve correct quantitation of analytes using an electrospray ionisation (ESI) interface. Thus, the feasibility of using external calibration was checked versus the use of different isotope‐labeled internal standards. The advantages of applying coupled‐column liquid chromatography (LC/LC) as an efficient clean‐up without any type of sample manipulation are also discussed. The combination of LC/LC with ESI‐MS/MS allows the direct analysis of free metabolites in urine, as the automated clean‐up performed by the coupled‐column technique is sufficient for the removal of interferences that suppress the ionisation of analytes in the ESI source. Using this procedure with external calibration, good precision and recoveries, and detection limits below 1 ng/mL are reached with analysis run times of around 8 min. The hyphenated technique LC/LC/ESI‐MS/MS is proved to be a powerful analytical tool, allowing the rapid, sensitive and selective determination of 4‐nitrophenol and 3‐methyl‐4‐nitrophenol in human urine without any sample treatment. Copyright © 2002 John Wiley & Sons, Ltd.