Determination of 2'-acetyl erythromycin and erythromycin in human tonsil tissue by HPLC with coulometric detection.

A simple and sensitive high-performance liquid chromatographic method was developed for the determination of 2'-acetyl erythromycin and erythromycin in human tonsil tissue. Methyl tert-butyl ether was used as the extraction solvent after alkalization of tissue homogenates. Separation was achieved on a reverse phase C-18 column. The mobile phase consisted of acetonitrile-methanol-tetrahydrofuran-sodium acetate buffer, pH 4.5. Eluted compounds were monitored by a coulometric detector in the oxidative screen mode. The quantitation limits of 2'-acetyl erythromycin and erythromycin were 0.20 and 0.30 mg/kg of tissue, respectively. The method was linear over the concentration range of 0.60-10.0 mg/kg of tissue for 2'-acetyl erythromycin and erythromycin.