MeOx-TMS derivatization for GC-MS metabolic profiling of urine and application in the discrimination between normal C57BL/6J and type 2 diabetic KK-Ay mice
The derivatization of metabolites is inevitable for GC-MS based global metabolic profiling. This article reports a GC-MS-based protocol using methoximation followed by silylation with BSTFA + 1%TMCS for the analysis of urine metabolites. The protocol has been thoroughly developed and optimized from derivatization to detection. The obtained chromatograms were much cleaner due to the absence of multi-peaks of sugars, such as glucose. Validation was performed with chemical standards and urine samples and proved that the methodology is efficient, rapid and reliable with linear responses, low detection limits and good precision and recovery. The method was successfully applied in the characterization of the metabolic phenotype of type 2 diabetic KK-Ay mice. Partial least squares-discriminant analysis (PLS-DA) and t-test analysis illustrated that there were seven metabolites (glyceric acid, hippuric acid, glucose, sorbitol, galactonic acid, myo-inositol, turanose) having distinct differences between normal C57BL/6J and type 2 diabetic KK-Ay mice.