The analysis of light hydrocarbons and sulfur compounds on porous layer capillary columns with a nonpolar phase

Abstract

Reproducibility of measurements of two main parameters (peak area and retention time) of components (carbon dioxide and sulfur compounds) of the model mixture with the composition close to natural gas was compared on two columns: a newly developed capillary column with a nonpolar phase poly(1-trimethylsilyl-1-propine) (PTMSP), size 30 m × 0.53 mm, and film thickness of the sorbent 2.8 mm, and a commercial column Rt-Q-BOND with a length 30 m, diameter 0.32 mm, and 10 m thick layer of nonpolar polydivinylbenzene sorbent. The application of such columns provides a satisfactory reproducibility of chromatographic characteristics of the compounds being analyzed: the relative root-mean-square deviation (RMSD) for retention times does not exceed 0.10 %, and RMSD for the measured peak areas is below 1.92 %. An insignificant deviation in the peak areas for sulfur dioxide and carbon disulfide (five consecutive injections of a sample) was observed on a capillary column Rt-Q-BOND. The corresponding RMSD values were 4.22 and 2.52 %. The signal response from analytes was recorded using a microcatharometer. The detection limit of sulfur-containing compounds on the column with PTMSP varies from 0.40·10 –3 to 0.82·10 –3 mg/ml. It was demonstrated for the first time that it is possible to selectively separate methane macrozone and propane-butane fraction from microimpurities of hydrocarbons and sulfur compounds, including carbon dioxide, hydrogen sulfide and mercaptans, on a capillary column with the film thickness 2.8 mm PTMSP.