ABSTRACT
Within the EU the use of dapsone (4,4-diaminodiphenylsulfone) is prohibited in food-producing animals and consequently it's included in the Annex IV of the Directive 90/2377/EC. A quantitative confirmatory method has been developed and validated according to the criteria defined in the Commission Decision 2002/657/EC, for the determination of dapsone in meat and milk. Samples, after homogenization in alkaline conditions and organic solvent extraction, were purified on silica gel solid phase extraction cartridges. The eluate was evaporated and redissolved in mobile phase and was analysed by liquid chromatography tandem mass spectrometry (LC-MS/MS) in positive electrospray ionisation (ESI) using deuterium labelled Sulphadimidine-d7 as internal standard. The calculated value for, decision limit, CCalpha is 0.12 microgkg(-1), and the detection capability; CCbeta value is 0.16 microgkg(-1).
Subject(s)
Anti-Infective Agents/analysis , Chromatography, Liquid/methods , Dapsone/analysis , Drug Residues/analysis , Meat/analysis , Milk/chemistry , Spectrometry, Mass, Electrospray Ionization/methods , Animals , Anti-Infective Agents/isolation & purification , Dapsone/isolation & purification , Drug Residues/isolation & purification , Reproducibility of Results , Tandem Mass SpectrometryABSTRACT
The analysis of carbimazole tablets in The British Pharmacopoeia, 1993, includes a quantitative thin layer chromatography (TLC) determination of methimazole. Repeated analysis of the same samples did not give similar results. The repeatability and reproducibility of the method was studied. It was proved that the residence time of the methimazole spot on the TLC plate is time dependent.
Subject(s)
Antithyroid Agents/analysis , Carbimazole/chemistry , Chromatography, Thin Layer/methods , Methimazole/analysis , Tablets/chemistry , Chromatography, High Pressure Liquid/methods , Evaluation Studies as Topic , Quality Control , Reproducibility of ResultsABSTRACT
A liquid chromatographic method for the analysis of ampicillin was examined in a collaborative study involving seven laboratories. The method included an isocratic part, which is used in the assay. The isocratic part is similar to the assay method for ampicillin of the US Pharmacopeia XXIII Revision. When the isocratic part is combined with gradient elution, the method is suitable for purity control. Six samples of ampicillin (anhydrous, trihydrate and sodium salt) with varying purity were analysed. The main component and related substances were determined. An analysis of variance proved the absence of consistent laboratory bias. The laboratory-sample interaction was significant. Estimates of the repeatability and reproducibility of the method, expressed as standard deviations of the result of the determination of ampicillin, were calculated to be about 0.9 and 1.1 respectively.
