Simultaneous determination of EDTA, sorbic acid, and diclofenac sodium in pharmaceutical preparations using high-performance liquid chromatography

Abstract

A simple high-performance liquid chromatographic method for simultaneous determination of ethylenediaminetetraacetic acid (EDTA), sorbic acid, and diclofenac sodium was developed and validated. Separation was achieved on a C(18) column (10 cm×4.6 mm) using gradient elution. The mobile phase consisted of acetonitrile-ammonium dihydrogen phosphate buffer solution (0.01 M, pH=2.5, containing 0.8% tetra-n-butyl ammonium hydroxide). The detector wavelength was set at 254 nm. Under these conditions, separation of three compounds was achieved in less than 10 min. The effect of two metal salts and metal concentration on peak area of EDTA was investigated. The pH effect on retention of EDTA and sorbic acid was studied. The method showed linearity for EDTA, sorbic acid, and diclofenac in the ranges of 2.5-100.0, 5.0-200.0, and 20.0-120.0 μg/mL, respectively. The within- and between-day relative standard deviations ranged from 0.52 to 1.94%, 0.50 to 1.34%, and 0.78 to 1.67% for EDTA, sorbic acid, and diclofenac, respectively. The recovery of EDTA, sorbic acid, and diclofenac from pharmaceutical preparation ranged from 96.0-102.0%, 99.7-101.5%, to 97.0-102.5%, respectively. To the best of our knowledge, this is the first report about simultaneous determination of EDTA, sorbic acid, and diclofenac.

Fig. 1

Chemical structure of disodium EDTA, sorbic acid, and sodium diclofenac

Fig. 2

A typical chromatogram for the mixture of disodium EDTA, sorbic acid, and diclofenac. Conditions: flow rate, 1.0 mL/min; mobile phase, acetonitrile–ammonium dihydrogen phosphate buffer solution (0.01 M, pH = 2.5, containing 0.8% tetra-n-butyl ammonium hydroxide); FeCl₃·6H₂O concentration, 250 μg/mL

Fig. 3

Effect of FeCl₃·6H₂O concentration in diluent on peak area of the Fe–EDTA complex. Conditions: flow rate, 1.0 mL/min; mobile phase, acetonitrile–ammonium dihydrogen phosphate buffer solution (0.01 M, pH = 2.5, containing 0.8% tetra-n-butyl ammonium hydroxide)

Fig. 4

The effect of pH on retention of the Fe–EDTA complex and sorbic acid. Conditions: flow rate, 1.0 mL/min; mobile phase, acetonitrile–ammonium dihydrogen phosphate buffer solution (0.01 M, containing 0.8% tetra-n-butyl ammonium hydroxide); FeCl₃·6H₂O concentration, 250 μg/mL

Fig. 5

HPLC chromatogram of Biofenac ophthalmic solution. Conditions: flow rate, 1.0 mL/min; mobile phase, acetonitrile–ammonium dihydrogen phosphate buffer solution (0.01 M, pH = 2.5, containing 0.8% tetra-n-butyl ammonium hydroxide); FeCl₃·6H₂O concentration, 250 μg/mL