Structure-gas chromatographic electron capture sensitivity relationships of some substituted 17alpha-acetoxyprogesterones.
Structure-electron capture sensitivity relationships were established for underivatized 17alpha-acetoxyprogesterones. While progesterone was very insensitive, 17alpha-acetoxyprogesterone had a response of 4.8 X 10(2) C/mole. Methyl groups in the A or B ring of 17alpha-acetoxyprogesterone had no effect. A keto group at C-6 was 25 times more sensitive (1.2 X 10(4) C/mole). A double bond at C-6,7 enhanced the sensitivity sevenfold (3.5 X 10(3) C/mole), but double bonds at C-1,2 or C-9,11 had only slight effect. Substitution at C-16 was important. A methyl group at C-16 had two and three times the sensitivity in the 3-keto delta4 and 3-keto delta4,6 series (1.1 X 10(3) and 1.1 X 10(4) C/mole), respectively. A methylene group at C-16, in contrast showed a six-and twofold greater sensitivity over the C-16 methyl in the two series (7 X 10(3) and 2.2 X 10(4) C/mole), respectively. The most sensitive compound was 6-dehydro-6methyl-16-methylene-17alpha-acetoxyprogesterone (melengestrol acetate). Its sensitivity was 2.2 X 10(4) C/MOL, Comparable to the most sensitive halo esters of steroid alcohols reported in the literature. Its electron capture coefficient was 3-7.6X 10(10) 1/mole. The coef-icient was independent of the detector temperature, indicating low activation energy for electron absorpiton.
The pulse-sampling technique for the study of electron-attachment phenomena.
Electron capture detector parameters in pulse sampling mode analyzed, noting kinetic processes, temperature effect, etc
Effect of oxygen on response of the electron-capture detector
Abstract : The electron-capture (EC) detector for gas chromatography has occupied an important position in analytical use because of its unique sensitivity and selectivity, particularly for compounds of biomedical and environmental significance. The importance of the detector has led to many studies of its characteristics, both to improve performance and to understand its basic mechanism. The recent development of the new technique of plasma chromatography for the first time permits one to obtain direct experimental data to observe the charged species being formed in the EC detector and their response and mobility under changing parameters. The report discusses findings using this technique.