GC-MS Analysis and PLS-DA Validation of the Trimethyl Silyl-Derivatization Techniques
Kamalrul Azlan Azizan, Syarul Nataqain Baharum, Habtom W. Ressom and Normah Mohd. Noor
DOI : 10.3844/ajassp.2012.1124.1136
American Journal of Applied Sciences
Volume 9, Issue 7
Problem statement: Comparison and validation analysis of the conventional and power-adjusted Microwave-Assisted (MA) techniques of TMS derivatization using Gas Chromatography-Mass Spectrometry (GC-MS) and Multivariate Analysis (MVA) of Partial Least Squares Analysis (PLS-DA). Further improvement of the conventional technique using vigorous shaking was tested and analyzed. Approach: Cross-validation and response permutation test of PLS-DA and S-plot of Orthogonal Partial Least Squares Discriminant Analysis (OPLS-DA) was applied to the extracellular data of Lactococcus lactis, which was analyzed by GC-MS. The analyzed samples were firstly derivatized using Methoximination (MeOX) and N-methyl-N-trimethylsilyl fluoroacetamide (MSTFA) followed by conventional and power-adjusted Microwave-Assisted (MA) heating treatment. Results: The supervised PLS-DA applied to extracellular data failed to show the same clustering results between conventional and power-adjusted Microwave-Assisted (MA) techniques. It was suggested that the type of heating used in the derivatization techniques had affected the detection of groups of metabolites. Furthermore using the UV-scaling method, S-plot and Variable Importance for Projection (VIP), about 40 metabolites that were responsible towards the clustering and separation showed in PLS-DA score plots were successfully indicated. Conventional technique with vigorous shaking showed clear clustering according to groups compared to MA technique. Conclusion: Type of heating applied to the TMS derivatization showed effects towards the detection of metabolites where conventional technique indicated strong clustering compared to MA technique.
© 2012 Kamalrul Azlan Azizan, Syarul Nataqain Baharum, Habtom W. Ressom and Normah Mohd. Noor. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.