Measurement of Distribution Constants Between Air and Solid Substrates Using Gas Chromatography for Quantification of Hydrocarbons in Solid Substrates via Headspace-Solid Phase Microextraction

Abstract

This study focused on the chromatographic measurements of the distribution constants of hydrocarbons at the air–solid interface for indirect quantification of the hydrocarbon compositions in solid substrates via headspace-solid phase microextraction (HS-SPME). Packed column gas chromatography and other experimental data were used to measure the distribution constants of six hydrocarbons (n-heptane, n-octane, n-nonane, toluene, p-xylene, and 1,2,4-trimethylbenzene) between the headspace (HS) and two solid substrates (cardboard and cotton fabric) at 60 and 90 °C. To validate the accuracies of the measured distribution constants in this work, model HS samples were prepared in vials containing known amounts of solid substrates and a mixture of vaporized hydrocarbons at 60 and 90 °C. These HS samples were analyzed with gas chromatography using both direct vapor analysis and HS-SPME. The experimental hydrocarbon compositions of HS samples were compared with the calculated HS compositions from the measured distribution constants and other experimental parameters. The Wilcoxon signed-rank test results indicated that the calculated hydrocarbon compositions of the model samples were comparable with the experimental hydrocarbon compositions. This work suggests that gas chromatographic measurements using packed columns can provide a reliable and convenient method for measuring the distribution constants of hydrocarbons between air and various solid substrates.