Alexander J. Debets

Learn More
48 Pharmaceutical Technology FEBRUARY 2005 S. Klick, PhD, is a team manager, Analytical Development, at AstraZeneca R&D (Mölndal Sweden), tel. 146 31 7761758, fax 146 31 7767337, Silke.Klick@astrazeneca.com. P.G. Muijselaar, PhD, is a senior analytical scientist and T.K. Gerding, PhD, is a manager, Sector Chemical & Pharmaceutical Development, at Solvay(More)
The effects of 3-monoalkyl- and 3,5-dialkyl-substitution on the cytotoxicity of paracetamol (PAR) in rat hepatocytes was studied. PAR is known to be bioactivated by the hepatic microsomal cytochrome P-450 containing a mixed-function oxidase system presumably to N-acetyl-para-benzoquinone imine (NAPQI), a reactive metabolite which upon overdosage of the drug(More)
This paper describes the characterisation of reversed-phase liquid chromatography (RPLC) columns using thermodynamic measurements. Retention versus 1/T data were used to construct Van't Hoff plots. The slope of these plots indicates the standard enthalpy of transfer of the analyte from the mobile to the stationary phase. The standard entropy can be(More)
Reversed-phase liquid chromatography using silica-based columns is successfully applied in many separations. However, also some drawbacks exist, i.e. the analysis of basic compounds is often hampered by ionic interaction of the basic analytes with residual silanols present on the silica surface, which results in asymmetrical peaks and irreproducible(More)
The automation of zone-electrophoretic sample treatment for liquid chromatography is described. The procedure is completely controlled from a liquid chromatograph. The carry-over of proteins from human serum under different experimental conditions was studied. The influence of the presence of proteins in the sample is illustrated with the anionic compound(More)
Recently, we have reported that 3,5-dialkyl substitution of paracetamol, in contrast to 3-monoalkyl substitution, prevented the paracetamol-induced toxicity in freshly isolated rat hepatocytes without having any effect on its cytochrome P-450 mediated bioactivation to reactive N-acetyl-p-benzoquinone imines (NAPQI). In the present study the mechanism of(More)
To enhance to compatibility of the on-line coupling of liquid chromatography (LC) with mass spectrometry (MS) for the analysis of basic pharmaceuticals, the use of volatile mobile phase systems in combination with miniaturised LC was investigated. Multifactor analysis of variance (MANOVA) was used to evaluate the data obtained for the various variables(More)
A new ball-mill extraction method for solid dosage forms was developed. It was used for tablets, and compared with a conventional (powdering and sonication) method applied in pharmaceutical analysis of solid dosage forms. The ball-mill sample preparation procedure is both quantitative and fast. No powdering, weighing and sonication steps are needed in the(More)
The reversed-phase liquid chromatographic analysis of basic pharmaceuticals can be problematic. Both the properties of the eluent and the stationary phase can influence the chromatographic performance. Therefore selection of suitable experimental conditions for the analysis of basic compounds can be difficult. This paper shows that the organic modifier and(More)
  • 1