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Biomedical subjects

M Donike

Publications and source records attributed to M Donike.

28 records · Page 2Linked to original sources
PubMed1977

[Determination of indolalkylamines after selective derivatisation (author's transl)].

The 1N-TMS-omegan-TFA-derivatives of indolalkylamines are suitable for estimation by combined gas chromatography and mass spectrometry for two reasons, viz. (1) Under electron impact charge stabilisation at the indole nucleus is favoured, so structure-specific ions form the base peak. For unsubstituted indoles m/e values of 202 are found and for hydroxyl-substituted indoles m/e values of 290. (2) The calibration curves of the derivatives are linear, even in the femtomole range. The 1N-TMS-omegan-derivatives can easily be obtained by trimethylsilylation with N-methyl-N-trimethylsilyltrifluoroacetamide containing catalytic amounts of N-trimethylsilylimidazole followed by acylation with N-methyl bis(trifluoroacetamide). The serotonin concentrations in different rat tissues are determined by this method of selective omegaN-trifluoroacylation-1N-trimethylsilylation and compared with the values obtained by pertrimethylsilylation.

Animals↗
PubMed1976

The detection of doping agents in blood.

Gas chromatographic screening procedures have been evaluated which permit the detection of stimulants and sedatives in blood after administration of pharmacological doses. The techniques actually used in sample preparations and gas chromatographic work are presented as well as examples of pharmacokinetic studies and postive dope cases. The use of sensitive and selective detectors like the nigrogen-specific detector or a mass spectrometer is absolutely essential for routine work, as for non-specific detectors the number of "false positives" leads to an intolerable work load for the laboratory.

Animals↗
PubMed1975

Excretion of norephedrine by man after oral administration of oxyfedrine.

After oral administration of oxyfedrine to healthy volunteers, norephedrine was identified in the urine by thin layer chromatography and gas liquid chromatography and mass spectrography. 30 hours after single oral doses of 8, 16 or 24 mg of oxyfedrine, about 4, 8 and 9 mg, respectively, of norephedrine were found in the urine, i.e. on a molar base 75-100% of the dose was excreted as norephedrine. The peak of excretion occurred within 2-4 hours after administration of the drug. No accumulation of oxyfedrine and/or its metabolite was observed after administration of 16 mg of oxyfedrine t.i.d. for three days. It could not be decided whether oxyfedrine was metabolized to norephedrine by liver enzymes, as in rats, or was spontaneously degraded to norephedrine, e.g. in duodenal fluid before absorption. 30-150 min after oral oxyfedrine (24 mg) norephedrine was demonstrable in duodenal fluid. Thus, in addition to the direct beta-sympathomimetic effects of oxyfedrine, it may also have indirect sympathomimetic effects because of the noradrenaline-releasing properties of its metabolite norephedrine.

Administration, Oral↗