title: Nitrate analysis in biological fluids by gas chromatography-nitrogen-phosphorous detection.
abstract: Nitrate analysis in body fluids is an important part of the study of nitric oxide metabolism. A sensitive, simple procedure for nitrate analysis was developed by producing nitrobenzene from the nitrate in the samples and benzene. The nitrobenzene produced was measured on a gas chromatograph (GC) equipped with a nitrogen-phosphorous detector. Cl-, which interfered with the derivitization procedure, was removed as silver chloride after precipitation with silver lactate. Rat urine samples were also analyzed after elution through a C18 reverse-phase sample preparation column to remove organic molecules that competed with benzene for the nitrate in the sample. A benzene derivative, 2-nitro-1,3-dimethylbenzene (2-nitro-m-xylene), was chosen as an internal standard for GC analysis. Recovery of nitrate was 67 +/- 2% in serum and 87 +/- 8% in urine. Sensitivity of the procedure was 1 microM. This procedure offers improvements in sensitivity, simplicity, and consistency over previously published procedures and makes possible the measurement of nitrate and determination of isotopic ratios by GC-MS on the same sample.
authors.affiliation: US Army Institute of Surgical Research, Fort Sam Houston, Texas 78234-6315, USA.
authors.forename: A A
authors.initials: AA
authors.lastname: Johnson
authors.forename: D G
authors.initials: DG
authors.lastname: Burleson
mesh_terms: D000818:Animals; D001826:Body Fluids / Q000378:metabolism*; D002056:Burns / Q000378:metabolism*; D002849:Chromatography, Gas / Q000379:methods*; D006801:Humans; D016014:Linear Models; D009566:Nitrates / Q000032:analysis* / Q000097:blood / Q000652:urine; D009569:Nitric Oxide / Q000378:metabolism*; D009584:Nitrogen; D010758:Phosphorus; D051381:Rats; D011917:Rats, Inbred Lew; D012015:Reference Standards; D012680:Sensitivity and Specificity
chemical_list: D009566:Nitrates; D010758:Phosphorus; D009569:Nitric Oxide; D009584:Nitrogen