The Gas Chromatographic Analysis of Sub-Microgram Quantities of Barbiturates Using a Flame Ionization Detector

Abstract

The gas chromatographic analysis of barbital, pentobarbital, and thiopental in organic extracts of biological fluids and tissues is possible in the concentration range 0.005–0.1 µg/µl. of solution injected, using a flame ionization detector and column temperature of 155°C or 175°C. The response is linear within certain, definite ranges. By appropriate setting of the electrometer range and attenuation as the barbiturate level is varied, a constant standard deviation of 0.3 sq. in. is obtained for the area response. If the area is taken relative to the area for barbital as an internal standard, this standard deviation is reduced to 0.07 sq. in. The effects of the shift in retention time as a function of barbiturate level, and the presence and avoidance of “ghost” peaks due to material absorbed on the column are discussed.