Comparison of two SPME fibers for differentiation of coffee by analysis ofvolatile compounds

Solid-phase microextraction (SPME) is based on the affinity of different he adspace compounds for the coating on a fiber. In the work described in this paper we evaluated and compared two different coatings, a medium polarity coating, Corbowax divinylbenzene (CW-DVB), and an apolar coating, polydimet hylsiloxane (PDMS), for the analysis and classification of coffee. PCA (pri ncipal-component analysis) was used to evaluate the results obtained by use of the two fibers and, at the same time, to determine their suitability fo r use for the classification and differentiation of coffee. When PCA is use d as a method of classification, using the 30 major peaks as variables, the results obtained with the CW-DVB fiber enable classification according to geographic origin; those obtained with the PDMS fiber enable classification based on variety (Arabica or Robusta).