Batch and Flow Injection Spectrophotometric Determination of Tetracycline Hydrochloride and Doxycycline Hyclate in Pharmaceutical Preparations

Abstract

New, simple and accurate batch and flow injection spectrophotometric
methods have been developed for the determinationsof tetracycline
hydrochloride (TCH) and doxycycline hyclate (DCH) in pharmaceutical
preparations. The methods are based on diazotization of
metchlopramide and coupling reaction with either TCH or DCH in alkaline
medium to form yellow–orange water soluble dye with absorption maxima
at 414 and 436 nm for TCH and DCH, respectively. A graphs of absorbance
versus concentration show that Beer’s law was obeyed over the
concentration ranges of 1 –52 μgmL-1 TCH and DCH for batch method and
of 8 – 240 μg mL-1 TCH and 5 – 350 μgmL-1 DCH for FIA method. The
limits of detection in batchmethods were 0.333 and 0.235μgmL-1for TCH
and DCH respectively, and in FIA methods were 0.895, 0.612 μgmL-1for
TCH and DCH respectively. Samplethroughputs in FIA procedures were 120
and 80samples per hour for TCH and DCH, respectively. Different chemical
and physical experimental parameters affecting on the development and
stability of the colored product were carefully studied and the proposed
methods were successfully applied for determination of TCH and DCH in
pharmaceutical preparations.