Spectrophotometric determination of tetracycline by coupling with diazotised 4-aminoantipyrine in presence of cetylpyridinium chloride

Abstract EN

A spectrophotometric method for the determination of microgram amounts of tetracycline–HCl (TCH) has been proposed.

The method is based on coupling of tetracycline-HCl with diazotized 4-aminoantipyrine in presence of cetylpyridinium chloride in alkaline medium.

The molar absorptivity of the formed dye reached to 1.92×104 l.mol-1.

cm-1 at 537 nm and Beer's law is obeyed within the range of 10-300 μg of tetracycline-HCl 10 / ml (i.e.1.0–30 ppm).

The color reaction was highly stable, a relative error ranged from - 2.5 to + 0.21 % and a relative standard deviation of ± 0.37 to ± 0.73 %, depending on concentration level of tetracycline-HCl.

The proposed method has been applied successfully to the determination of tetracycline-HCl in pharmaceutical preparations.