Cooking Your Data: challenging the use of orthodox SPME extraction temperatures in biological analysis

Abstract

Solid-Phase Microextraction (SPME) is a widely used analytical technique for measuring volatile organic compounds in biosamples. The current literature on SPME recommends sample extraction temperature optimisation based primarily on obtaining a chromatographic profile with intense, narrow, well-separated peaks. However, studies in our laboratory comparing different extraction temperatures showed that increasing temperature significantly decreased the differences between the case-control study groups, and thus the relevance of the data to the research hypothesis. Contrary to recommendations, the least optimal chromatographic profile gave the most statistically significant results when looking at the differences between two groups. We speculate that the reliance on chromatographic characteristics has arisen for historical reasons. Advanced deconvolution software was developed late last century, yet the power of computer-based feature separation over chromatographic separation has not been fully exploited in some areas of applied mass spectrometry. Our study highlights the need for evidence-based rather than theory-based chromatographic method development. Keywords: SPME, Solid Phase MicroExtraction, GC-MS, Gas Chromatography-Mass Spectrometry, Deconvolution