Use of Proton Transfer Reaction in Spectrophotometric Determination of Tetracycline in the Presence of 2,6-diaminopyridine reagent

Abstract

A precise, reproducible, rapid, and highly sensitive spectrophotometric procedure was created for the micro determination of Tetracycline hydrochloride (TCH) in bulk form and pharmaceutical formulation. The suggested method depends on the proton transfer reaction by coupling the substance to be determined with the reagent 2,6-diaminopyridine in the basic medium to form a colored complex that shows the maximum absorption value at the wavelength of 385 nm. To reach the optimum conditions, different factors were studied. It was observed that Beer's law is followed in the range of (3-32 μg/mL) with a molar absorptivity of 18.755 L/mol.cm. The methods indicated a high degree of sensitivity in terms of limit of detection which was described to be as low as 0.137 μg/mL while the quantification limit was 0.458 μg/mL. The average recovery value was 97.45%, and the relative standard deviation value (RSD) was less than 4.3%. The correlation ratio with the detector was 2:1 (drug: reagent). Therefore, the proton transfer reaction was then applied successfully for the quantitative assay of tetracycline in its pharmaceutical preparations with satisfactory results.