Optimum performance of capillary GC columns as a function of tube diameter and film thickness under various operating conditions. Computer program for calculation of H-ū curves and minimum analysis times

✍ Scribed by Leclercq, P. A. ;Cramers, C. A.

• Publisher: John Wiley and Sons
• Year: 1985
• Tongue: English
• Weight: 601 KB
• Volume: 8
• Category: Article
• ISSN: 0935-6304
• DOI: 10.1002/jhrc.1240081112

✦ Synopsis

The Golay-Giddings and Poiseuille equations are used to derive equations for the calculation of the maximum plate number and minimum time conditions for given columns at fixed, but selectable, outlet pressures. In addition, expressions are presented for the determination of minimum analysis times for separation problems requiring given plate numbers. In this instance, the optimum column length can be calculated as a function of outlet pressure. A Basic computer program, incorporating the equations for the various optima, together with the H -l curves, is described. Input variables are either column length or desired plate number, column diameter, film thickness, capacity ratio of the solute, column outlet pressure, separation temperature, and carrier gas. The carrier gas viscosity is automatically calculated in thecaseof hydrogen, helium, or nitrogen. Forthesegases, and if the solute is a n-alkane, the diffusivity of the solute in the mobilephaseiscalculated. In thiscase, thecarbon numberof the solute is needed in the computation.

For high molecular weight polydimethylsilicone phases (e.g. SE-30), the program can approximate the diffusivity of n-alkanes in the stationary phase at the given temperature as a function of the carbon number. Of course, manually entered valuesof viscosity and diffusion coefficients can be included in the calculations.