Determination of (2,3-epoxypropyl)trimethylammonium chloride, (3-chloro-2-hydroxypropyl)trimethylammonium chloride, and (2,3-dihydroxypropyl)trimethylammonium chloride by capillary electrophoresis

Direct quantification of anorethidrani disuccinate and determination of sterol metabolites by chemical derivatization combined with LC-MS/MS: Application to a Phase I pharmacokinetic study in humans

Anorethidrani disuccinate (ACP) is a domestically designed A-decarbonized steroid that is currently being investigated in Phase I clinical trials for the treatment of solid tumors. Only the parent drug exhibited antitumor activity; its sterol metabolite M2 showed obvious antiestrogenic effects. We have developed a rapid, sensitive, and robust liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the direct quantification of ACP and a chemical derivatization method that can be used to quantify M2 derivatized with glycidyl trimethyl ammonium chloride (GTMA). A simple protein precipitation procedure was performed to quantify ACP. Injections were obtained within 3.5 min on an Eclipse Plus Phenyl-Hexyl column (50 mm × 2.1 mm i.d., 1.8 μm) with gradient elution; the calibration curve was linear over the range of 2.00-8000 ng/mL. For quantification of M2 in plasma, analytes were extracted by protein precipitation and converted to their GTMA derivatives at 60 °C for 2 h at pH 12; the analytes and coelutants were separated on a Luna C8(2) column (50 mm × 2.0 mm i.d., 5.0 μm). The precision (RSD) and accuracy (RE) of the intra- and interday determinations were within 10%. The derivatization procedure is a novel method for sterol determination by LC-MS/MS. The results confirmed the usefulness of this method for characterizing the pharmacokinetic profiles of ACP and its major metabolite M2 in a Phase I pharmacokinetic study.

Synthesis of cationic alkylated chitosans and an investigation of their rheological properties and interaction with anionic surfactant

Two methods were used to alkylate high M_W chitosan with glycidyltrimethylammonium chloride (GTAC) in order to produce chitosan derivatives that are water-soluble throughout the pH range. In addition, a novel chitosan derivative was created by alkylating one of the products with the GTAC analogue Quab 342 containing C12 alkyl chains. The phase behaviour and rheological characteristics of the chitosan derivatives were studied in the presence of anionic surfactant. The derivatives were found to form soluble complexes at low and high SDS concentrations and that the Quab 342 derivative was able to form gels.

Determination of the Degree of Substitution of Cationic Guar Gum by Headspace-Based Gas Chromatography during Its Synthesis

This study reports on a headspace-based gas chromatography (HS-GC) technique for determining the degree of substitution (DS) of cationic guar gum during the synthesis process. The method is based on the determination of 2,3-epoxypropyltrimethylammonium chloride in the process medium. After a modest pretreatment procedure, the sample was added to a headspace vial containing bicarbonate solution for measurement of evolved CO₂ by HS-GC. The results showed that the method had a good precision (relative standard deviation of <3.60%) and accuracy for the 2,3-epoxypropyltrimethylammonium chloride measurement, with recoveries in the range of 96-102%, matching with the data obtained by a reference method, and were within 12% of the values obtained by the more arduous Kjeldahl method for the calculated DS of cationic guar gum. The HS-GC method requires only a small volume of sample and, thus, is suitable for determining the DS of cationic guar gum in laboratory-scale process-related applications.