Comparison of different derivatising reagents in identification of milk metabolites using GC–MS

Abstract

Derivatisation comprises one of the prerequisites for metabolomic analysis through GC–MS. Three commonly used derivatising reagents, N-methyl-trimethylsilyltrifluoroacetamide (MSTFA), N,O-bis-(trimethylsilyl) trifluoroacetamide (BSTFA) and BSTFA with catalyst (1% trimethylchlorosilane) were compared for detection of metabolites in milk. Pooled cow milk samples were subjected to derivatisation individually by MSTFA, BSTFA and BSTFA + TMCS and then individually injected in GC–MS for analysis. A total of 49, 52 and 56 metabolites were detected in milk using GC–MS after derivatising with MSTFA, BSTFA and BSTFA + TMCS, respectively. Among all detected metabolites, 37 metabolites were commonly detected irrespective of derivatising reagent and rest were specific to specific derivatising reagents. In all derivatising reagents, carbohydrate metabolites were detected in higher number followed by lipid and amino metabolites. In detection of metabolites by GC–MS, derivatisation by MSTFA was found to be superior than BSTFA and BSTFA + TMCS due of its wide range of identified metabolites.