REUSABILITY OF SOLID-PHASE EXTRACTION COLUMNS DURING THE HPLC ANALYSIS OF SOME MACROLIDE ANTIBIOTICS IN SERUM AND URINE

The re-usability of C18 solid-phase extraction (SPE) cartidges was assessed utilizing two different analytical procedures developed for the analysis of erythromycin and josamycin in human serum and urine. A statistical procedure using confidence intervals was employed in order to determine a 10% change in drug recovery on re-use with a 95% degree of certainty. The results obtained indicated that the SPE cartridges could be successfully re-used up to three times for serum and urine samples containing physiological concentrations of erythromycin base and propionate. However, in the case of josamycin, results were inconsistent after the second re-use of the extraction cartridges for serum samples. Reproducible results, however, were still obtained for urine samples using the same SPE cartridges up to four times. The results indicate that although succesful re-use of SPE cartridges is possible, each drug and associated extraction conditions need to be carefully assessed prior to implementing such re-use. © 1990 Friedr. Vieweg & Sohn Verlagsgesellschaft mbH.