Applicability of Capillary Gas Chromatography to Substance Identification in Toxicology by Means of Retention Indices

Three capillary columns, set up in a routine screening system, were tested in temperature-programmed runs. A narrow-bore fused silica capillary, Carbowax deactivated and with a methylsilicone liquid phase, was found to be unstable at higher temperatures, giving irreproducible results and retention indices that varied considerably from those obtained on packed columns. The two other columns, a wide-bore glass capillary and a narrow-bore fused silica capillary, were polysiloxane-deactivated and had a dimethylpolysiloxane liquid phase. Although both showed good stability, reproducibility, and load capacity, retention indices for various drugs still showed discrepancies as compared to corresponding values on packed columns