Specific Features of the Gas Chromatographic Analysis of Samples in High-Boiling Solvents Using Capillary Columns with a Low Split Ratio of the Carrier Gas Flow

Abstract

Gas chromatographic analysis of samples in high-boiling polar organic solvents is characterized by several features. First, the resolution of the components depends on the injector temperature (Tinj), which should not be lower than the boiling point (Tbp) of the solvent. Second, the retention indices (RIs) of the components eluted before the polar solvent zone are somewhat overestimated compared to the retention indices of the components eluted after this zone. And, third, the so-called “discrimination effects ” are observed for these samples, first of all, the dependence of the absolute peak areas of the components from Tinj. It is confirmed that such dependence does not affect the results of quantitative analysis by the method of internal normalization. Nevertheless, the possibility of using application of this and other methods is recommended, and the condition of Tinj ≥ Tbp should be satisfied to verify the thermal stability and mutual compatibility of the components of the test samples. These features are set in the analysis of both a solution of model analytes in 1,3-butanediol (Tbp = 207°C) and a sample of the food flavoring, which is a solution of a complex mixture of components in dipropylene glycol (Tbp 222–236°C). The reason for these effects is a slowdown in the process of sample evaporation and dynamic modification of the stationary phase of the chromatographic column by high-boiling polar solvents.