After stereospecific oxidation, trimethylsilylated methyl esters of mono- and diunsaturated fatty acids were analyzed by combined gas-liquid chromatography-chemical ionization mass spectrometry. The positions of original double bonds were deduced from the fragment ions produced by the cleavage of the carbon-carbon bond between two trimethylsilyl ethers. These fragment ions were recorded at m/e ...

1. A method is described for the quantitative isolation of bile acids from cellular material. Homogenates of rat liver are freeze-dried and extracted exhaustively with 95% (v/v) ethanol containing 0.1% (v/v) of aq. ammonia (sp.gr. 0.88) and purified by anion-exchange chromatography on Amberlyst A-26. 2. The extracted bile acid conjugates are subjected to either of two hydrolytic procedures, one...

A methodology to quantify cholesterol oxidation products (COPS) in dairy products has been established by gas-liquid chromatography (GLC). Lipids were extracted according to the Folch method and saponified at room temperature using sodium hydroxide in methanol/benzene (3:2, v/v). Cholesterol oxides were derivatized to trimethylsilyl ethers and resolved by GLC, confirming the structures of chole...

We have measured the bile acids in human serum as methyl ester-trimethylsilyl ethers by gas chromatography-mass spectrometry (GC-MS) using an electron ionization procedure. The overall method was validated and the detection limit (0.4 mumol/l), linearity (2-30 mumol/l), intra-day and inter-day precision, accuracy and recovery (96.2% for nor-23-deoxycholic acid as internal standard) were measure...

2-Pentanone and 2-pentanone-l,l,l-d3 were treated with three-fold excesses of lithium diisopropylamide (LDA) or lithium hexamethyldisilazide (LHMDS) in tetrahydrofuran (THF) with and without hexamethylphosphoric triamide (HMPA, 3 mol per mol of base) at temperatures ranging from 24 to — 70 °C. The deuterium kinetic isotope effects calculated from the product ratios (mea­ sured by GLC as trimeth...

Metabolism of steroid hormones with anabolic properties was studied in vitro using human recombinant CYP3A4, CYP2C9 and 2B6 enzymes. The enzyme formats used for CYP3A4 and CYP2C9 were insect cell microsomes expressing human CYP enzymes and purified recombinant human CYP enzymes in a reconstituted system. CYP3A4 enzyme formats incubated with anabolic steroids, testosterone, 17alpha-methyltestost...

Tris(trimethylsilyl)silylmagnesium bromide, (Me^SiX^SiMgBr, reacts with 2.5-diisopropylbenzaldehyde to give 2,5-diisopropylphenyl-tris(trimethylsilyl)silylmethanol (1). With sodium hydride in THF compound 1 undergoes a rearrangement through 1,3-Si,O-trimethylsilyl mi­ gration affording bis(trimethylsilyl)silyl-(2,5-diisopropylphenyl)-trimethylsiloxy-methane (4). The deprotonation of 1 with orga...