Determination of ramoplanin in human urine by high-performance liquid chromatography with automated column switching

Ramoplanin is a novel glycolipodepsipeptide antibiotic, currently undergoin g clinical trials. This method describes the determination of ramoplanin by direct injection of human urine into a coupled-column liquid chromatograph ic system. An internal-surface reversed-phase column has been used for on-l ine sample clean-up and enrichment. Analytical separation of ramoplanin and MDL 62 456 used as internal standard, has been achieved on a ABZ+ reversed -phase column with ammonium acetate buffer-acetonitrile-methanol according to a gradient profile. Analytes were detected by their UV absorbance at 270 nm. The limit of quantitation was 0.1 mu g/ml urine and the limit of detec tion was found to be 0.035 mu g/ml, corresponding to 13.7 pmol/ml. Linearit y was determined in the range 0.1-2 mu g/ml. Precision (relative standard d eviation) ranged from 0.71 to 8.75% and the accuracy from -9.9 to 11.6%. Di fferent human sources were tested and no interference between analytes and urine constituents was observed. The method is simple and rapid, requiring a total analysis time of 35 min per sample and reaching greater selectivity and accuracy than microbiological assays. (C) 1999 Elsevier Science B.V. A ll rights reserved.