Gas chromatographic method with minimal sample consumption for quality control of 13C-mixed triglycerides used in clinical diagnosis

Abstract

Exocrine pancreatic insufficiency (EPI) can be comfortably diagnosed by a breath test using the mixed triglyceride 2-octanoyl (1-¹³C)-1,3 distearoyl glycerol (¹³C-MTG). However, it is not fully accepted as a routine test yet as no vendor provides a certified product for clinical applications. Current recommended methods for quality control of triglycerides are not compatible with the produced expensive small batches of ¹³C-MTG. In this article, two procedures were miniaturized and optimized: one to confirm the structure by a regiospecific enzymatic reaction and another to check the purity via a methyl esterification. Both pretreated samples were then analyzed by gas chromatography coupled to mass spectrometry (GC-MS). The proposed methods showed good selectivity for the structure confirmation and good linearity with external standards for the purity control: R² values were higher than 0.995, accuracy was in the 98-100% range and excellent repeatability (RSD <1.4%) was achieved.

Keywords: Gas chromatography; Mass spectrometry; Mixed triglycerides; Regiospecific enzymatic reaction.