Diazo-coupling reaction in spectrophotometric Determination of doxycycline in pure and its dosage forms

Document Type : Original Article

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Chemistry Department /.College of Science / University of Mosul / Mosul ,Iraq

Abstract

A simple and accrued spectrophotometric method was suggested for the determination of doxycycline in pure form and in capsule dosage. The method relied on the formation of an azo dye by coupling of doxycycline with the diazotized reagent 1-amino-4-nitronaphthalein (prepared by mixing equal mole of 1-amino-4-nitronaphthalein and sodium nitrite) in an alkaline medium using sodium hydroxide as a base to give a colored azo dye soluble in aqueous solution, and it gave ahighest absorbance at the wavelength 466 nm. All parameters (these parameters included the effect of the amount of diazotized 1-amino-4-nitronaphthalein, the type and amounts of base and the time of stability) affected the intensity of colored azo dye have been studded and the optimal conditions have been selected. The linearity was from 0.5 to 20 µg/ ml and above 20 µg doxycycline/ ml gave negative deviation from Beer's law. The molar absorptivity, Sandell's sensitivity, Limit of detection (LOD), and limit of quantitation (LOQ) were 7.778 x103 l/mol.cm, 0.0595 µg/cm2, 0.2969 µg/ml,and 0.9880 µg/ml respectively. The method was successfully applied in estimating doxycycline in its dosage form (capsule) from various drugs companies.

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History

  • Receive Date: 27 July 2022
  • Revise Date: 28 August 2022
  • Accept Date: 05 September 2022

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