Quantitative Determination of Olaquindox in Animal Feed

JPC – Journal of Planar Chromatography – Modern TLC - A quantitative thin layer chromatographic (TLC) method on silica gel, with ethyl acetate–acetone–alcohol, 62 + 40 + 3...     

Separation of tetracycline and its related substances by capillary zone electrophoresis

Tetracycline was separated from its main impurities 4-epitetracycline, anhydrotetracycline, 4-epianhydrotetracycline, chlortetracycline, and demethyltetracycline by capillary electrophoresis. Systematic method development was performed in which following parameters were consecutively optimized: type and pH of the buffer, buffer concentration, type and concentration of organic modifier, voltage and temperature. Qualitative and quantitative aspects of the method are compared with liquid chromatography.     

Analysis of doxycycline by capillary electrophoresis

Summary Doxycycline is a semi-synthetic broad spectrum antibiotic with improved serum half-lie. Potential impurities are 4-epidoxycycline, 6-epidoxycycline, 4,6-epidoxycycline, metacycline and 2-acetyl-2-decarboxamidodoxycycline. Method development has been undertaken to investigate the potential of capillary electrophoresis for the analysis of doxycycline. The influence of buffer type, buffer pH and concentration was systematically examined, then that of capillary temperature and applied voltage. All the potential impurities could be separated at 15 °C on a 44 cm × 50 μm I.D. fused silica capillary (effective length to detector, 38 cm) with sodium carbonate (70 mM) - EDTA (1 mM), pH 10.50, as background electrolyte and with a voltage of 12 kV. The relative standard deviation was 2.2 % for doxycycline. The limit of detection and quantification for doxycycline were 0.2 and 0.4 %.     

Spectrophotometric determination of submicro quantities of Ajmaline

A spectrophotometric method for the determination of 5–100 μg samples of ajmaline is described. Ajmaline gives a red colour with concentrated nitric acid, which is measured at 510 mμ after a definite time interval. The limits of interference from serpentine and ajmalicine are given. The method can be applied directly for the estimation of ajmaline in pharmaceutical preparations.