title: Voltammetric investigation of macrolides by an HPLC-coulometric assay.
abstract: Voltammograms of macrolides, including anhydroerythromycin A, azithromycin, erythromycin A, erythromycin A enol ether, pseudoerythromycin A enol ether, oleandomycin and tylosin have been investigated using a dual electrode cell in combination with a high-throughput LC method. The half-wave potentials (E(1/2)) of the seven macrolides investigated ranged from 0.734 to 0.866 V, and the current responses reached the maxima at over 1.0 V. The current response of the downstream electrode displayed a non-linear behavior at high potentials over +0.75 V, probably because of polarization of solvent components, e.g., water. The HPLC-coulometric assay was optimized with the potentials of the upstream and downstream electrodes at +0.65 and +0.85 V, respectively. This method is suitable for detection of 14- and 15-membered macrolides (sensitivity<0.05 microg ml(-1)), but not for a 16-membered macrolide, tylosin (sensitivity>0.1 microg ml(-1)). The assay shows interferences from biomatrices in rat's blood plasma and serum, and human urine, but they were effectively removed by a cold acetonitrile extraction method.
authors.affiliation: Division of Microbiology, National Center for Toxicological Research, U.S. Food and Drug Administration, 3900 NCTR Road, Jefferson, AR 72079, USA.
authors.forename: Yong-Hak
authors.initials: YH
authors.lastname: Kim
authors.forename: Jairaj V
authors.initials: JV
authors.lastname: Pothuluri
authors.forename: Carl E
authors.initials: CE
authors.lastname: Cerniglia
mesh_terms: D000818:Animals; D002853:Chromatography, Liquid / Q000379:methods*; D004563:Electrochemistry / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D018942:Macrolides / Q000097:blood* / Q000737:chemistry / Q000652:urine*; D015394:Molecular Structure; D051381:Rats; D011916:Rats, Inbred F344; D015203:Reproducibility of Results; D013678:Technology, Pharmaceutical / Q000379:methods
chemical_list: D018942:Macrolides