Optimization of the Identification Algorithm Using Reference Values of Gas Chromatographic Retention Indices

The capabilities of an algorithm for comparing experimental and reference values of gas chromatographic retention indices (RIs) are discussed. This algorithm was designed to eliminate significant elements of uncertainty inherent in most modern recommendations, namely, fixed values of their permissible deviations ΔRI. The proposed algorithm is oriented toward the use of variable values of deviations ΔRI = (RIref – RIexpt). It is applicable to multicomponent mixtures in which individual components with known reference values of retention indices can be reliably identified. This makes it possible to calculate the parameters of the regression equations ΔRI = (RIref – RIexpt) = aRIexpt + b with the subsequent use of these equations to recalculate the experimental RI values into the corrected values RIcorr = RIexpt + ΔRI. For example, this algorithm allows one to use reference RI values for semistandard stationary phases containing 5% phenyl groups to identify compounds by indices determined on standard nonpolar polydimethylsiloxane stationary phases and vice versa. It is applicable to both statistically processed data (presented in the format mean value ± permissible deviation) and to the results of single determinations.