Precise extraction and measurement is essential for any method used in metabolomics as significant metabolic effects can be observed as small chemical changes. The measurement of fatty acids is a well-established metabolomic profiling technique. The simplest method for looking at these profiles is to derivatise the sample of interest, trans-esterifying lipids to form the methyl esters of the fatty acids, with a subsequent liquid-liquid extraction (LLE) clean-up step. Using the Dual Head GERSTEL MultiPurpose Sampler (MPS), it was possible to automate this derivatisation and extraction with immediate injection after preparation. This approach ensures all the samples are prepared using an identical protocol, hence minimising analytical variability. The use of the Agilent 7200 GC/Q-TOF enables more selective target ion extraction as well as confirmation of analyte identity and potential structural elucidation of unknown or novel metabolites. Good reproducibility was obtained for the straight chain fatty acid methyl esters present (CV 3.9-6.9% for C14-C22), confirming the data quality obtained. The GERSTEL system and Agilent Q-TOF could be used for a number of other derivatisation and extraction protocols, such as Folch and Fiehn that are routinely used in metabolomics.
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The Automated Derivatisation and Extraction of Fatty Acids Using the GERSTEL MPS Autosampler and Agilent 7890/7200 GC/Q-TOF