Analysis of synthetic gastrointestinal drugs in adulterated traditional Chinese medicines by HPCE

Six synthetic gastrointestinal drugs, cimetidine, homatropine, metocloprami de, pirenzepine, ranitidine, and scopolamine butylbromide, which can be fou nd as adulterants in traditional Chinese medicines were assayed simultaneou sly, within 6 min., using high performance capillary electrophoresis. The e lectrolyte was a buffer solution containing 100 mM phosphate buffer (NaH2PO 4/ H3PO4, pH 2.5) and 5% acetonitrile. Applied voltage was 20.5 kV and temp erature was 30 degrees C. 3-Benzyl-5-(2-hydroxyethyl)-4-methylthiazolium ch loride was used as an internal standard and the detector was set at 214 nm. The effects of buffer pH and acetonitrile concentration on separation are important. The relative standard deviations of these gastrointestinal drugs for intra-day and inter-day analyses were 0.78-2.15% and 1.10-2.75%, respe ctively. The recoveries of the synthetic drug adulterants in traditional Ch inese medicinal formula ranged from 97.3 to 102.4%.