Title: Quantification of (15)N-nitrate in urine with gas chromatography combustion isotope ratio mass spectrometry to estimate endogenous NO production
Authors: Houben, Els
Hamer, Henrike Maria
Luypaerts, Anja
De Preter, Vicky
Evenepoel, Pieter
Rutgeerts, Paul
Verbeke, Kristin # ×
Issue Date: Jan-2010
Series Title: Analytical Chemistry vol:82 issue:2 pages:601-607
Abstract: The use of stable isotope labeled substrates and subsequent analysis of urinary nitrate, forms a noninvasive test for evaluation of the in vivo NO metabolism. The present paper describes a new method for simultaneous quantification of (15)N-nitrate and total nitrate with gas chromatography combustion isotope ratio mass spectrometry (GC-C-IRMS). Nitrate, isolated from urine with a nitrate selective resin, was reduced to nitrite using copperized cadmium. Subsequently, Sudan I was formed by diazotation. Sudan II was added as internal standard, and both molecules were analyzed with GC-C-IRMS as tert-butyldimethylsilyl derivatives. The accuracy was determined during a recovery study of two different known nitrate concentrations and two (15)N-enrichments. A recovery of 101.6% and 103.9% for total nitrate and 107.6% and 91.2% for (15)N-nitrate was obtained, respectively. The validated method was applied on complete 72 h urine collections after intravenous administration of (15)N-nitrate and (15)N-arginine in humans. On average, 51.8% (47.0-71.0%) of administered (15)N-nitrate was excreted, while 0.68% (0.44-1.17%) of (15)N-arginine was metabolized to nitrate. In conclusion, this method can be used for accurate simultaneous determination of (15)N-nitrate and total nitrate concentrations in urine and can be applied in clinical studies for noninvasive evaluation of NO metabolism in vivo.
ISSN: 0003-2700
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Translational Research in GastroIntestinal Disorders
Laboratory of Nephrology
× corresponding author
# (joint) last author

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