METHODOLOGICAL ASPECTS OF HEADSPACE SPME - APPLICATION OF THE RETENTION INDEX SYSTEM

The applicability of the retention index system to headspace solid pha se microextraction (HS-SPME) was investigated. In headspace SPME, the two equilibria gas phase/matrix and fiber coating/gas phase have to be considered. In this paper the equilibrium fiber coating/gas phase is discussed separately to characterize it more detailed and to investiga te several methodical aspects. Therefore, the different distribution c onstants K-fiber/gas of n-alkanes, which were used for reference compo unds, were related to their Kovats retention indices. The validity of the derived linear relationship log K-fiber/gas versus retention index I is demonstrated for various examples. This relation is helpful for the assessment of distribution constants of substances not available a nd for the choice of a suitable fiber coating. Furthermore, quantifica tion of analytes in the gas phase can be done without authentic substa nces.