Sulfated, sulfopropyl and carboxymethyl -, - and -CDs were characterized by CE-ESI-MS using an acidic BGE with anodic MS detection and a basic BGE with cathodic MS detection. Isomers of the sulfated ...CDs comigrated in both systems. The acidic BGE with anodic MS detection resulted in slightly better separation of the isomers of the sulfopropyl CDs, which were separated according to the number of substituents. In the case of carboxymethyl CDs, isomers with an identical number of substituents but with a different substitution pattern with regard to substitution of the primary and secondary hydroxyl groups of the CDs could be separated using the basic BGE. The separation of the LL and DD enantiomers of dipeptides and tripeptides using the CDs was studied with regard to the amino acid sequence and the nature of the CDs. Standardized conditions with regard to buffer pH, CD concentration and voltage were applied. The peptides were analyzed at pH 2.5 as positively charged compounds and at pH 5.3 as neutral zwitterions. The -CD derivatives were more effective chiral selectors for the investigated peptides followed by the -CD derivatives. The -CDs were the least effective selectors. The enantiomer migration order depended on both the CD and the amino acid sequence of the peptides. For several combinations, pH-dependent reversal of the enantiomer migration order was also observed.
... working in targetted MS-MS mode prevents the detection of other compounds. ... it is difficult to develop methods for simultaneous analysis of high numbers of pesticides.
In Cannabis sativa, Delta *D9-Tetrahydrocannabinolic acid-A ( Delta *D9-THCA-A) is the non-psychoactive precursor of Delta *D9-tetrahydrocannabinol ( Delta *D9-THC). In fresh plant material, about ...90% of the total Delta *D9-THC is available as Delta *D9-THCA-A. When heated (smoked or baked), Delta *D9-THCA-A is only partially converted to Delta *D9-THC and therefore, Delta *D9-THCA-A can be detected in serum and urine of cannabis consumers. The aim of the presented study was to identify the metabolites of Delta *D9-THCA-A and to examine particularly whether oral intake of Delta *D9-THCA-A leads to in vivo formation of Delta *D9-THC in a rat model. After oral application of pure Delta *D9-THCA-A to rats (15 mg/kg body mass), urine samples were collected and metabolites were isolated and identified by liquid chromatography-mass spectrometry (LC-MS), liquid chromatography-tandem mass spectrometry (LC-MS/MS) and high resolution LC-MS using time of flight-mass spectrometry (TOF-MS) for accurate mass measurement. For detection of Delta *D9-THC and its metabolites, urine extracts were analyzed by gas chromatography-mass spectrometry (GC-MS). The identified metabolites show that Delta *D9-THCA-A undergoes a hydroxylation in position 11 to 11-hydroxy- Delta *D9-tetrahydrocannabinolic acid-A (11-OH- Delta *D9-THCA-A), which is further oxidized via the intermediate aldehyde 11-oxo- Delta *D9-THCA-A to 11-nor-9-carboxy- Delta *D9-tetrahydrocannabinolic acid-A ( Delta *D9-THCA-A-COOH). Glucuronides of the parent compound and both main metabolites were identified in the rat urine as well. Furthermore, Delta *D9-THCA-A undergoes hydroxylation in position 8 to 8-alpha- and 8-beta-hydroxy- Delta *D9-tetrahydrocannabinolic acid-A, respectively, (8-Hydroxy- Delta *D9-THCA-A and 8 Delta *b-Hydroxy- Delta *D9-THCA-A, respectively) followed by dehydration. Both monohydroxylated metabolites were further oxidized to their bishydroxylated forms. Several glucuronidation conjugates of these metabolites were identified. In vivo conversion of Delta *D9-THCA-A to Delta *D9-THC was not observed.
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