Peak Capacity Calculation in Capillary Gas Liquid Chromatography

A method is suggested for the determination of the peak capacity in isothermal and temperature-programmed high resolution gas chromatography (HRGC). The calculation is based on the integral by Grushka and Giddings, requiring that the dependence of the peak width on the retention time be known. Regression analysis of experimental data gave evidence that in isothermal and linear temperature-programmed HRGC where the temperature rate is the single variable parameter, the dependence of the peak width on retention time can be approximated by a linear equation. Substitution of this linear dependence in the integrand gives an integral which can be solved analytically. For temperature-programmed HRGC with two variable parameters, viz. the time of initial isothermal period and the temperature rate, the above dependence can be fitted with a cubic equation. The resulting integral is more complex and has to be solved numerically. The peak capacities calculated by the procedure suggested and by the use of the separation number ( TZ ) are in a good agreement.