Classification and comparison of capillary columns by determination of the solution enthalpy of polar and non polar probes

Robust estimation of thermodynamic parameters (ΔH, ΔS and ΔCp) for prediction of retention time in gas chromatography - Part II (Application)

For this work, an analysis of parameter estimation for the retention factor in GC model was performed, considering two different criteria: sum of square error, and maximum error in absolute value; relevant statistics are described for each case. The main contribution of this work is the implementation of an initialization scheme (specialized) for the estimated parameters, which features fast convergence (low computational time) and is based on knowledge of the surface of the error criterion. In an application to a series of alkanes, specialized initialization resulted in significant reduction to the number of evaluations of the objective function (reducing computational time) in the parameter estimation. The obtained reduction happened between one and two orders of magnitude, compared with the simple random initialization.

Separation characteristics of wall-coated open-tubular columns for gas chromatography

The application of the solvation parameter model for the classification of wall-coated open-tubular columns for gas chromatography is reviewed. A system constants database for 50 wall-coated open-tubular columns at five equally spaced temperatures between 60 and 140 degrees C is constructed and statistical and chemometric techniques used to identify stationary phases with equivalent selectivity, the effect of monomer chemistry on selectivity, and the selection of stationary phases for method development. The system constants database contains examples of virtually all commercially available common stationary phases.