Determination of carbonyl compounds in beer by derivatisation and headspace solid-phase microextraction in combination with gas chromatography and mass spectrometry

Headspace solid-phase microextraction (SPME) followed by gas chromatography and mass spectrometry was applied for quantification of 41 chemically diverse carbonyl compounds in beer. Therefore, in-solution derivatisation with o-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA) combined with SPME was optimised for fibre selection, PFBHA concentration, extraction temperature and time and ionic strength. Afterwards, the method was calibrated and validated successfully and extraction efficiency was compared to sampling with on-fibre derivatisation. In-solution derivatisation enabled the detection of several compounds that were poorly extracted with on-fibre derivatisation such as 5-hydroxymethylfurfural, acrolein, hydroxyacetone, acetoin, glyoxal and methylglyoxal. Others, especially (E)-2-nonenal, were extracted better with on-fibre derivatisation.