Chiral analysis of methylphenidate and dextromoramide by capillary electrophoresis

Abstract

Capillary electrophoretic methods have been developed to separate the enantiomers of methylphenidate (MPH) and dextromoramide. For MPH separation was achieved with heptakis (2,6-di- O-methyl)-β-cyclodextrin (DMCD) as chiral selector in a 100 m M phosphoric acid buffer adjusted to pH 3.0 with triethanolamine. Commercial samples of d,l- erytho-MPH HCl and d,l- threo-MPH HCl were analysed using the method. There was no evidence of the presence of d,l- threo-MPH HCl in d,l- erytho-MPH HCl and vice versa. The ratio of the enantiomers was determined for each diastereoisomer. Hydroxypropyl-β-cyclodextrin was the chiral selector of choice for the chiral separation of the enantiomers of moramide. The separation which gave a resolution of about 3.5 was achieved in 4 min using only a 6 cm of length of capillary. In a sample of dextro- R-moramide tartrate only a small quantity (4.9% w/w) of levo- S-moramide was detected with this method.