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Carbon isotopic ratio analysis by gas chromatography/combustion/isotope ratio mass spectrometry for the detection of gamma‐hydroxybutyric acid (GHB) administration to humans
Author(s) -
Saudan Christophe,
Augsburger Marc,
Mangin Patrice,
Saugy Martial
Publication year - 2007
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.3298
Subject(s) - chemistry , chromatography , mass spectrometry , formic acid , isotope ratio mass spectrometry , elution , solid phase extraction , gas chromatography , detection limit
Since GHB (gamma‐hydroxybutyric acid) is naturally produced in the human body, clinical and forensic toxicologists must be able to discriminate between endogenous levels and a concentration resulting from exposure. To suggest an alternative to the use of interpretative concentration cut‐offs, the detection of exogenous GHB in urine specimens was investigated by means of gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS). GHB was isolated from urinary matrix by successive purification on Oasis MCX and Bond Elute SAX solid‐phase extraction (SPE) cartridges prior to high‐performance liquid chromatography (HPLC) fractioning using an Atlantis dC18 column eluted with a mixture of formic acid and methanol. Subsequent intramolecular esterification of GHB leading to the formation of γ ‐butyrolactone (GBL) was carried out to avoid introduction of additional carbon atoms for carbon isotopic ratio analysis. A precision of 0.3‰ was determined using this IRMS method for samples at GHB concentrations of 10 mg/L. The 13 C/ 12 C ratios of GHB in samples of subjects exposed to the drug ranged from −32.1 to −42.1‰, whereas the results obtained for samples containing GHB of endogenous origin at concentration levels less than 10 mg/L were in the range −23.5 to −27.0‰. Therefore, these preliminary results show that a possible discrimination between endogenous and exogenous GHB can be made using carbon isotopic ratio analyses. Copyright © 2007 John Wiley & Sons, Ltd.