Effects of the Discrimination of Sample Composition with the Use of Split Injection into Gas Chromatographic Capillary Columns

Resumo

The manifestation of noticeable effects of the discrimination of sample composition upon split injection into short capillary columns with large diameters at small splitting ratios is discussed. They consist in the anomalously strong dependences of the peak areas of even volatile components on the injector temperature, the solvents used and, to a lesser extent, on the amounts of injected samples. It is proposed to consider the following criteria for assessing the degree of manifestation of these factors: (1) the dependence of the absolute peak areas of different analytes on the injector temperature and (2) the analogous dependence of the relative peak areas of the same components in different solvents. In this case, the relative peak areas of various components in the same solvents remained almost constant regardless of the injector temperature. The above effects complicate quantitative determinations based on the measurement of absolute peak areas (the method of internal normalization and the determination of distribution coefficients in partition chromatography). For these purposes, it is preferable to use standard capillary columns with split sample injection at a sufficiently high splitting ratio.