POSTCOLUMN ZIRCONIUM CHELATION AND FLUORESCENCE DETECTION FOR THE LIQUID-CHROMATOGRAPHIC DETERMINATION OF TETRACYCLINES

A novel highly sensitive liquid chromatographic method for the determi nation of some tetracycline antibiotics has been developed. It is base d upon the measurement of fluorescence induced by complexation of tetr acyclines with the zirconium cation, which is added post-column to the liquid chromatographic eluate. The zirconium reagent concentration an d post-column configuration were optimized. The effect of time upon th e stability of the chelates was studied. The fluorescence intensity wa s linear in a concentration range of 0.01-10 mu g ml(-1) tetracycline. The proposed method has already been applied to the residue analysis for tetracycline, oxytetracycline and chlortetracycline in bovine milk . The most striking advantages of the method over the reported methods in the literature are the higher sensitivity and specificity achieved . The detection limits of the assay (signal-to-noise ratio = 4:1) were 1 ng ml(-1), 2 ng ml(-1) and 4 ng ml(-1) for oxytetracycline, tetracy cline and chlortetracycline, respectively.