P-3
The rapid characterisation of hop essential oils using GC-TOFMS. Hops (Humulus lupulus L.) are used by the brewing industry to add
bitterness and flavour to beer. The analysis of hop essential oils helps in
determining both hop quality and varietal discrimination. A new approach for the
rapid analysis of essential oils is reported using capillary gas
chromatography-time of flight mass spectrometry (GC-TOFMS) and this has been compared to
conventional quadrupole GCMS analysis. Using narrow-bore capillary columns (0.18
mm) in combination with high spectral acquisition frequencies, inherent problems
of peak coelutions were overcome using spectral deconvolution algorithms. High
TOFMS acquisition rates afforded superior spectral purity that, in conjunction
with greater high mass ion transmission than the quadrupole, gave excellent
spectral data for species such as humulone and lupulone. Using a GC-TOFMS
method, a reduction in total analysis time by a factor of 10 was achieved,
successfully identifying 40 key common components. Modifying this method to
incorporate quantitative analysis could enable a rapid method of quality control
for hops.
Mark Roberts received a BSc in microbiology from the University of
Manchester in 1998. He then worked for a year in QA at AstraZeneca before
beginning a PhD in analytical chemistry at the University of Leeds. He is
currently in his final year.
MARK T. ROBERTS and Alastair C. Lewis. School of the Environment, University of
Leeds, Woodhouse Lane, Leeds, LS2 9JT UK.