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.
Quantitation of non-halogenated compounds by electron-capture gas chromatography
Abstract The use of electron-capture gas chromatography for the quantitation of non-halogenated compounds that do not contain a nitro group is reviewed. The electrophore most often used is the conjugated carbonyl group; about fifteen examples are given on selective and sensitive determinations. Sulphonamide-containing compounds represent another interesting group useful for quantitative work. Finally some electrophore compounds belonging to various classes are mentioned.
Approximation of electron capture response factors for highly electrophilic compounds
Abstract A theoretical upper limit of electron attachment rate constants is derived, based on collision-limited electron interaction with polarizable molecules. This limit is shown to give upper limits for electron capture response factors. Evidence is presented showing that this limit is approached to within a factor of two for a wide variety of highly electrophilic compounds. It is suggested that this limit can be used as an approximation for electron capture response factors for suitable compounds, and that properly chosen derivatizing reagents may allow detection of derivatives with fairly accurate prediction of response factors.