oa South African Journal of Chemical Engineering - Electrochemical behavior study of salicylic acid following azo dye formation with 2,4-dinitrophenylhydrazine : analytical evaluation - research

Volume 25 Number 1
  • ISSN : 1026-9185



A new simple, accurate and cost-effective chronoamperometry (CA) - based approach coupled with azo coupling reaction has been put forward for quantitative analysis of salicylic acid. The reaction involves a two-step process of oxidation of the 2,4-dinitrophenylhydrazine (DNPH) by potassium iodate to give a 2,4-dinitrophenylhydrazinium cation at 0e5 C and coupling with salicylic acid (SA) to form red salicylic acid-derived azo dye. Electrochemical impedance spectroscopy, square wave voltammetry and chronoamperometry methods were used to characterize the electrochemical behavior of the salicylic acidderived azo dye. Studies on different variables affecting the reaction were optimized. Under the optimal conditions, amperometric studies showed that the current response exhibits a wide linearity range from 0.1 to 0.0005 mmol L1 for SA and the limit of detection and quantification are found to be 0.0001 and 0.0015 mmol L1 (S/N ¼ 3 & 10) respectively. Therefore, the developed method was successfully applied for routine determination of SA in pharmaceutical samples.

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