GC–MS Measurement of 13C-Enrichment of Lactic Acid in Sepsis Plasma

Abstract

Sepsis is a systemic inflammatory response syndrome arising from infection. The plasma lactic acid level is a reliable marker of sepsis. A novel procedure based on microwave-assisted derivatization followed by gas chromatography–mass spectrometry (GC–MS) has been developed for the rapid measurement of 13C-isotope enrichment of lactic acid in plasma. The derivatization conditions and method validation were studied. The method was applied to the measurements of isotopic enrichment of lactic acid in the plasma of a rabbits which had received the tracer ([1,2,3-13C3] lactic acid) by carotid infusion 2.5 h before blood sampling from the portal vein. These results show that the proposed method has excellent precision (RSD less than 4.57%), linearity (slope = 0.9936; r2 = 0.9998), accuracy and selectivity. The analytical results show that microwave-assisted derivatization coupled to GC–MS is a rapid method for the direct isotopic measurement of deproteinised plasma. The method could be of great interest for metabolic studies in animal models and human patients.