Dr. John Shaw Billings and The American Climatological Association.
Explore the source record for details and available documents.
Archives↗
Biomedical subjects
C Roos
Publications and source records attributed to C Roos.
GOVERNMENT DOCUMENTS IN MEDICINE.
Explore the source record for details and available documents.
Journal Article↗
Determination of delta 9-tetrahydrocannabinol-11-oic acid in urine as its pentafluoropropyl-pentafluoropropionyl derivative by GC/MS utilizing negative ion chemical ionization.
A rapid and sensitive GC/MS method for the determination of delta 9-tetrahydrocannabinol-11-oic acid in urine is presented. Enzymically hydrolyzed urine was extracted with hexane/ethyl ether followed by a one-step derivatization procedure with a mixture of pentafluoropropionic anhydride and pentafluoropropanol. By using negative ion chemical ionization and selected ion monitoring, a 200-fold higher detectability was observed, compared with El or positive ion chemical ionization under the conditions used. Samples were analyzed with split injection on a fused silica capillary column with a total analysis time of less than four minutes. A deuterium labelled analogue was used as internal standard and the precision for the overall method was measured to 3.4% for a sample concentration of 230 ng/mL, and to 6.7% for 3 ng/mL. The minimum detectable amount was below 1 ng/mL.
Chemical Phenomena↗
Metabolism of bambuterol in rat liver microsomes: identification of hydroxylated and demethylated products by liquid chromatography mass spectrometry.
The oxidative metabolism of (R,S)-bambuterol in rat liver microsomes was studied. Metabolite fractions were analyzed by thermospray LC-MS. The use of an equimolar mixture of deuterium-labeled and unlabeled bambuterol facilitated the mass spectrometric identification of the metabolites. Six metabolites, formed via hydroxylation, demethylation, and hydrolytic reactions, were identified. The demethylated metabolites were found to be chemically unstable under physiological conditions. It is likely that the complex biotransformation of bambuterol into terbutaline is one factor contributing to the long duration of action of bambuterol.
Animals↗