title: Determination of l-carnitine using enantioselective, potentiometric membrane electrodes based on macrocyclic antibiotics.
abstract: In order to determine the enantiopurity of l-carnitine three enantioselective, potentiometric membrane electrodes were proposed for the assay of l-carnitine. The electrodes were designed using macrocyclic glycopeptide antibiotics-vancomycin and teicoplanin. Acetonitrile was added to the teicoplanine to design a modified teicoplanine based electrode. The linear concentration ranges for the proposed enantioselective membrane electrodes were 10(-4) to 10(-2)moll(-1) for electrodes based on vancomycin and teicoplanin and 10(-5) to 10(-2)moll(-1) for electrode based on teicoplanin modified with acetonitrile. The slopes of the electrodes were 56.5mV per pl-carnitine; 54.5mV per pl-carnitine and 58.3mV per pl-carnitine for vancomycin-, teicoplanin- and teicoplanin modified with acetonitrile-based electrodes, respectively. The enantioselectivity was determined over d-carnitine. The proposed electrodes could be employed reliably for the assay of l-carnitine raw material and its pharmaceutical formulation, Carnilean((R)) capsules. The surfaces of the electrodes are stable and easily renewable by polishing on alumina paper.
authors.affiliation: Department of Chemistry, University of Pretoria, Pretoria 0002, South Africa.
authors.forename: Alexander A
authors.initials: AA
authors.lastname: Rat'ko
authors.forename: Raluca-Ioana
authors.initials: RI
authors.lastname: Stefan
authors.forename: Jacobus Koos F
authors.initials: JK
authors.lastname: van Staden
authors.forename: Hassan Y
authors.initials: HY
authors.lastname: Aboul-Enein