RESUMEN
A capillary electrophoresis (CE) method is described for the simultaneous determination of copper and iron after complexation with a readily biodegradable chelating agent, [S,S']-ethylenediaminedisuccinic acid (EDDS), in wood pulp. CE separation was performed in a fused-silica capillary (50 microm i.d.; total length, 65 cm) with an electrolyte containing 25 mM borate buffer and 0.5 mM CTAB at pH 7.0 and an applied voltage of -25 kV. The samples were introduced by applying a 50 mbar pressure for 2 s, and detection of the complexes was monitored at 245 nm. The methodology performance of the methods was evaluated in terms of the linearity, limit of detection (LOD), limit of quantitation (LOQ) and reproducibility. The applicability of the method was demonstrated for the analysis of copper and iron in wood pulp.
RESUMEN
A simple and rapid high-performance liquid chromatographic method for the separation and determination of process-related impurities of sildenafil was developed. The separation was achieved on a reversed-phase C18 column using acetonitrile-0.05 M potassium dihydrogen orthophosphate (70:30 v/v) as a mobile solvent at a flow rate of 1.0 ml/min and UV detection at 230 nm. The method was used not only for quality assurance, but also for monitoring the chemical reactions during the synthesis of sildenafil. It was found to be specific, precise and reliable for the determination of all process-related impurities of sildenafil in bulk drugs and formulations.