Prediction of second and cross virial coefficients of blended mobile phases in gas chromatography

Abstract

The second-interaction virial coefficients of vapors of potential interest as carriers in gas chromatography are considered in detail. Those examined include the monatomic gases helium, neon, argon, and krypton, the homonuclear diatomic compounds hydrogen, nitrogen, and oxygen, the heteronuclear inorganic species carbon monoxide, carbon dioxide, nitrous oxide, sulfur dioxide, water, hydrogen chloride, and ammonia, and the organic materials methane through n-pentane, carbon tetrachloride, and fluorotrichloromethane. Experimentally derived pure-component virial coefficients B/sub ii/ for all species except water and hydrogen chloride are shown to fit quadratic equations of the form (chosen so as to reflect the principle of corresponding states) B/sub ii//V/sub ii//sup c/ = f(T/sub ii//sup c//T), where the superscripts c indicate a critical value. The temperature range to which the temperature-invariant coefficients apply spans for all substances that for which accurate experimental data are available which, for many, is 200-950 K. Methods of prediction of the cross virial coefficient B/sub ii/ are detailed, and the results are then employed with B/sub ii/ for quantitative theoretical evaluation of the compositional variation of second-interaction virial coefficients B/sub M/.