Estimation of air/coating distribution coefficients for solid phase microextraction using retention indexes from linear temperature-programmed capillary gas chromatography. Application to the sampling and analysis of total petroleum hydrocarbons in air.

The paper describes a method to quantify hydrocarbons in air exclusively on the basis of chromatographic parameters without the need for calibration. A simple technique is presented to estimate distribution coefficients (K) between air and the poly(dimethylsiloxane) solid phase microextraction (SPME) fiber coating using the linear temperature-programmed retention index system (LTPRI). There is a linear relationship (r(2) = 0.99989) between the log K for a series of n-alkanes and LTPRI, thus providing a means by which establishing a K for any peak in a chromatogram is possible given its published or experimentally determined LTPRI. This alternative approach to establishing K values significantly enhances and simplifies the use of SPME for sampling and analyzing air for quantification of compounds without the need for fiber calibration. Analysis of a group of 29 isoparaffinic compounds and a group of 33 aromatic compounds showed excellent agreement between their theoretical air to fiber distribution coefficients based on LTPRI and the experimentally obtained distribution coefficients. In addition, for a very complex mixture of organics such as gasoline, SPME can establish a total petroleum hydrocarbon in air level using LTPRI. This method was carefully evaluated, and the results were essentially identical between standard procedures and the proposed simple procedure described in the paper.