Continuous-flow chemiluminometric determination of tetracyclines in pharmaceutical preparations and honey by oxidation with N-bromosuccinimide.

A continuous flow chemiluminometric method for determining 0.050-3.00 micrograms cm-3 of tetracycline, 0.50-5.00 micrograms cm-3 of oxytetracycline, 0.50-7.00 micrograms cm-3 of doxycycline and chlorotetracycline and 0.30-3.00 micrograms cm-3 of demeclocycline in pharmaceutical preparations and honey is described. The method is based on the chemiluminescence produced by the action of N-bromosuccinimide on tetracyclines in alkaline solution. The emission intensity is greatly enhanced by the presence of ammonia. The procedure is automated and solutions can be analysed at a rate of 130 h-1 with a relative error of about 2%. During evaluation of possible interferences of the method, recoveries from solutions with common excipients and other concomitant compounds were in the ranges 97.8-104.0 and 96.6-109.4%, respectively. Recoveries of various tetracyclines from commerical formulations and honey samples were in the ranges 95.2-103.7 and 89.2-106.6%, respectively. The results obtained for the assay of commerical pharmaceutical preparations compared well with those obtained by an official method and demonstrated accuracy and precision (< or = 5%).