Enhancing the volatile profile at sub-ambient temperature by using vacuum-assisted HS-SPME. Case study on fish spoilage

Headspace solid-phase microextraction (HS-SPME) is an easy, effective and selective technique for the analysis of volatiles and semi-volatiles compounds. However, long equilibration time is requested to reach optimized extraction conditions. Equilibrium is reached faster in agitating or heating the sample. Heating sample increases the extraction kinetics. However, artefact production can be a limitation, especially for matrices sensible to temperature. Beside other strategies to improve extraction kinetics, the use of vacuum has been recently and successfully proposed to speed up the extraction without increasing the temperature.
The aim of this work was to investigate and compare the use of Vac-HS-SPME to regular HS-SPME sampling from complex solid food like fish. The performances of Vac-HS-SPME were investigated at different sampling temperatures and times. In the present work, the effects of extraction temperature, sampling time and SPME phase were investigated using traditional one variable at a time approach. A series of compounds, markers of fish spoilage and covering the entire chromatogram, were selected for the comparison. Gas chromatography coupled to a single quadrupole mass spectrometry was used for the final determination.
Comparable results were obtained between sampling at 5 °C under vacuum condition and at 40 °C at atmospheric pressure. This work showed that the use of vacuum can be a powerful approach for volatiles sampling in refrigerated foods.