Journal of Chromatography & Separation Techniques
Open Access

Variations in GC–MS response between analytes and deuterated analogs

4^th World Congress on Chromatography

August 07-09, 2017 | Rome, Italy

Muhammed Alzweiri

University of Jordan, Jordan

Posters & Accepted Abstracts: J Chromatogr Sep Tech

Abstract :

Isotopic analogue is commonly used as an appropriate internal standard. It was reported that analytes have usually higher mass responses than their equimolar deuterated analogues (DAs) leading to quantification discrepancy. Standard addition method on dimethyl azelate (DMA) and d6- dimethyl azelate (d6-DMA) was adopted to examine possible reasons for the problem. Cross contribution of mass responses, intermolecular deuterium-hydrogen exchange during chromatographic separation, and deviation in mass ionization response of C-H against C-D bonds were studied as possible reasons for this discrepancy. GC-MS analysis revealed that neither cross contribution of ions nor H2/H exchange were possible reasons behind the difference in responses between DMA and d6-DMA relying on linearity and trans-esterification studies respectively. On the other hand, a study of carbon nucleus relaxation conducted by C13-NMR depicted that energy dissipation through C-D bond is faster than that through the C-H bond; relaxation rate of carbonyl carbon in d6-DMA and DMA were 9 and 3 sec-1 respectively. Accordingly, the energy transfer through the carbon skeleton of analytes and its mass ionization degree are more efficient than those in their DA counterparts. Conclusively, GC-MS analysis of analyte, relying on the assumption of equal response with its DA, generates overestimated analytical results of analytes.

Biography :

Email: m.alzweiri@ju.edu.jo