title: Comparison of 15N analysis by optical emission spectrometry and mass spectrometry for clinical studies during total parenteral nutrition.
abstract: During total and stable parenteral nutrition, a branched chain amino acid enriched solution containing [15N]leucine was infused into a patient to determine the fate of the nitrogen administered through this formulation. Measurements of 15N isotopic enrichments were performed on the same biological samples (urinary urea, total plasma proteins and albumin) by optical emission spectrometry (OES) and mass spectrometry (MS) to determine if OES with its specific advantages (cost, handling maintenance) constituted even with low enrichments a useful alternative technique to MS considered as the reference method. The average 15N% enrichments are 0.5% for urinary urea, 0.21% for total plasma proteins and 0.14% for albumin. The coefficients of correlation between both series of 15N% enrichment measurements realized by MS and OES vary from 0.999 to 0.998 and 0.988, respectively, for urinary urea, total plasma proteins and albumin. These results show that OES constituted a very useful analytical technique to obtain reliable information in clinical metabolic studies when low 15N enrichments must be determined.
mesh_terms: D000597:Amino Acids, Branched-Chain / Q000008:administration & dosage / Q000378:metabolism*; D001798:Blood Proteins / Q000032:analysis*; D006801:Humans; D008297:Male; D013058:Mass Spectrometry; D008875:Middle Aged; D009587:Nitrogen Isotopes; D010289:Parenteral Nutrition, Total; D012709:Serum Albumin / Q000032:analysis*; D013053:Spectrophotometry; D014508:Urea / Q000652:urine*
chemical_list: D000597:Amino Acids, Branched-Chain; D001798:Blood Proteins; D009587:Nitrogen Isotopes; D012709:Serum Albumin; D014508:Urea