N. Esfahani, M. Moghadam and M. Valipour, “Rapid and Efficient Aromatization of Hantzsch 1,4-Dihydropyridines with Potassium Peroxomonosulfate Catalyzed by Manganese(III) Schiff Base Complexes,” Journal of the Iranian Chemical Society, Vol. 5, No. 2, 2008, pp. 244-251.

has been cited by the following article:

• TITLE: A Novel Spectrophotometric Method for Determination of Five 1,4-Dihydropyridine Drugs in Their Tablets and Capsules Using Vanillin Reagent

  AUTHORS: Mohamed A. El Hamd, Sayed M. Derayea, Osama Hassan Abdelmageed, Hassan F. Askal

  KEYWORDS: Spectrophotometric Method; 1, 4-DHP; Validated; Selective; Vanillin Reagent

  JOURNAL NAME: American Journal of Analytical Chemistry, Vol.4 No.3, March 28, 2013

  ABSTRACT: A selective and new spectrophotometric method is described for determination of five 1,4 dihydropyridine drugs (1,4- DHP); namely nifedipine (NIF), nicardipine (NIC), nimodipine (NIM), felodipine (FEL) and amlodipine (AML). The method is based on a coupling reaction between the cited drugs and vanillin reagent in acidic condition. Under optimized conditions, the red coloured products were measured at 500 nm for NIF, NIC, NIM and FEL or at 479 nm for AML. Molar absorptivities were ranged from 0.575 × 104 － 1.065 × 104 l·mol-1·cm-1, Beer’s law was obeyed at 5 - 70 μg/mL concentration range and the limit of detection was ranged from 0.150 - 1.500 μg/mL. The proposed method was successfully extended to pharmaceutical preparations tablets and capsules and comparison by Student’s t-test and variance ratio F-test showed no significant difference.