The effects of adsorption of solutes on glassware and teflon in the calculation of partition coefficients for solid-phase microextraction with 1PS paper

Abstract

Solid-phase microextraction presents numerous advantages over traditional extraction techniques. However, the determination of partition coefficients is not as simple as it may appear. For very nonpolar compounds, such as polycyclic aromatic compounds, adsorption to the glass wall of the extraction vial and the Teflon coating of the stir bar may be quite significant. These interactions must be taken into account when calculating partition coefficients. Failing to do this may lead to large errors in the value of the partition coefficient, particularly for very nonpolar compounds. Three polar compounds and seven polycyclic aromatic hydrocarbons were partitioned individually between Whatman 1PS paper and water solutions of the compounds. The partition coefficiencts were calculated with two equations, and detailed mass balance data were acquired for the adsorption of the solute on the stir bar, glass vial, and 1PS paper. The mass data were compared with the partition coefficients, and important conclusions were made about the practical use of the partition coefficients.