科研之友
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摘要
Incorporation of deuterium from deuterium oxide ((H2O)-H-2) into biological components is a commonly used approach in metabolic studies. Determining the dilution of deuteriumin the body water (BW) pool can be used to estimate body composition. We describe three sensitive GC/MS/MS methods to measure water enrichment in BW. Samples were reacted with NaOH and U-C-13(3)-acetone in an autosampler vial to promote deuterium exchange with U-C-13(3)-acetone hydrogens. Headspace injections were made of U-C-13(3)-acetone-saturated air onto a 30-m DB-1MS column in electron impact-mode. Subjects ingested 30ml (H2O)-H-2, and plasma samples were collected. BW was determined by standard equation. Dual-energy X-ray absorptiometry scans were performed to calculate body mass, body volume and bone mineral content. A four-compartmental model was used to estimate body composition (fat and fat free mass). Full-scan experiments generated an m/z 45 peak and to a lesser extent an m/z 61 peak. Product fragment ions further monitored included 45 and 46 using selected ion monitoring (Method1), the 61> 45 and 62> 46 transition using multiple reaction monitoring (MRM; Method2) and the neutral loss, 62> 45, transition (Method3). MRM methods were optimized for collision energy (CE) and collision-induced dissociation (CID) argon gas pressure with 6 eV CE and 1.5mTorr CID gas being optimal. Method2 was used for final determination of (H2O)-H-2 enrichment of subjects because of lower natural background. We have developed a sensitive method to determine (H2O)-H-2 enrichment in BW to enable measurement of FM and FFM.
- 出版日期2015-6
