Du Preez, J.L.Swan, Gerry E.Verwoerd, Daniel Wynand2013-09-092013-09-0920131995Gummow, B, Du Preez, JL & Swan, GE 1995, 'Paired-ion extraction and high-performance liquid chromatographic determination of diminazene in cattle plasma: a modified method’. Onderstepoort Journal of Veterinary Research, vol. 62, no. 1, pp. 1-4.0330-24657102127047I-7222-2013 7003908833N-9314-2014http://hdl.handle.net/2263/31062The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.The high-performance liquid chromatographic method published by Aliu & Odegaard (1983) was found to give poor peak separation when used to determine plasma diminazene concentrations in cattle. Before bioequivalence studies could be carried out, the method had to be modified. Solid-phase extraction with acetonitrile/0,025 M Na-octane sulphonate and 2% acetic acid as eluent, followed by sample concentration, gave recoveries of > 90% for diminazene and the internal standard. A mobile phase of acetonitrile/0,005 M Na-octane sulphonate, 0,1% triethylamine, pH 3,2 with acetic acid on a Nova Pak C 18 column was used for the analysis. Wavelength switching was used to determine the internal standard (imidocarb) and diminazene at their respective wavelengths of maximum absorbance, resulting in a fivefold increase in the limit of detection for diminazene. The modified method attained a detection limit of 2 ng/ml (peak 4x baseline noise) , limit of quantitation of 10 ng/ml (coefficient of variation < 15 %) and an accuracy of > 96% over the range from 10-5000 ng/ml.en© ARC-Onderstepoort (original). © University of Pretoria. Dept of Library Services (digital).Veterinary medicinePaired-ion extractionLiquid chromatographic determinationDiminazeneCattle plasmaVeterinary medicine -- South AfricaArticle