Thermostable Open Tube Capillary Columns for the High Resolution Gas Chromatography of Human Urinary Steroids

Abstract

A new procedure has been developed for the preparation of open tube glass capillary columns (0.3 mm, i.d.) for use with non-polar phases at elevated temperatures (200–300°C). An all-glass inlet system provides complete sample evaporation before the splitter zone, traps contaminating nonvolatiles, and prevents decomposition of sensitive components. In addition, a carrier gas control system was devised that permits stable and reproducible adjustment of split ratio and capillary inlet pressure. These capillary columns are useful for studying metabolic profiles. They have been used for the high resolution separation of methoxime-trimethylsilyl (MO-TMS) and benzyloxime-trimethysilyl (BO-TMS) derivatives of human urinary steroids. “Methylene unit” (MU) values for the major steroid derivatives have been determined, and are different from values observed for packed columns. The temperature stability and lifetime of these columns is promising. After six months of continual use, only negligible changes in column characteristics could be detected, although these separations require temperature programming up to 300°C.