5] Electron-capture techniques for steroid analysis

Abstract

Publisher Summary Gas–liquid chromatography (GLC) using electron-capture (EC) detection offered the first rapid approach for the measurement of steroid hormones at nanogram and picogram levels. Although some of these GLC-EC methods have been superseded by radioimmunoassay techniques, they remain as useful and independent methods of hormone measurement that can be applied to biological samples of diverse origin without interference from extraneous proteins or salts that may be present in the sample. The principles of gas–liquid chromatography have been amply considered in previous discussions. Gas–liquid chromatography offers the opportunity to both purify and quantify a sample in a single operation by combining high efficiency chromatography with a sensitive detection system. One of the most sensitive GLC detection systems developed to date is electron-capture spectrometry, utilizing the ability of certain compounds to absorb electrons. When such a compound enters a low voltage field, its ability to absorb or capture electrons results in disruption of the existing current. This negative deflection is amplified and results in a very sensitive detection system. Unfortunately, most steroidal compounds have little inherent electron-capturing properties. It is thus necessary to prepare a derivative of the steroid that will enhance its ability to capture electrons, thereby enabling the steroid derivative to register a strong signal in the EC detector.