A splitless injection technique by cold trapping on capillary column

A split injection technique which is used for high resolution of gas chromatographic peaks usually lowers the sensitivity of detection, since it leads only a small part of sample to the separation column. In this paper, a splitless injection technique was investigated to make the analytical sensitivity higher, by using a part of quartz capillary column as a cold trap for sample gases. A part of quartz capillary column near the sample injector of about 20 cm was taken out of the oven of instrument, and about 6 cm part of the capillary was placed in a Dewer's vessel for the condensation and evaporation of sample gas. The sample gas in He carrier was collected in the column with liquid air and released instantaneously with hot water. The trapping time of 0.1 to 1.0 ml of sample gas was 5 to 10 min. A good resolution of gas chromatographic peaks was shown with a reference mixture of 14 hydrocarbons with only exception of peaks of 2-methylpentane and 2, 3-dimethylbutane. Excellent reproducibility and sensitivity of 70 to 120 times over a conventional split injection technique by this method were also shown.