Spectrophotometric study of etodolac complexes with copper (II) and iron (III)

J AOAC Int. 2005 Nov-Dec;88(6):1637-43.

Abstract

A rapid, simple, and selective method was developed for the determination of etodolac. The method depends on complexation of etodolac with copper (II) acetate and iron (III) chloride followed by extraction of complexes with dichloromethane and then measuring the extracted complexes spectrophotometrically at 684 and 385 nm in case of Cu (II) or Fe (III), respectively. Different factors affecting the reaction, such as pH, reagent concentration, and time, were studied. By use of Job's method of continuous variation, the molar ratio method, and elemental analysis, the stoichiometry of the reaction was found to be in the ratio of 1:2 and 1:3, metal:drug in the case of Cu (II) and Fe (III), respectively. The method obeys Beer's law in a concentration range of 2.00-9.00 and 0.50-2.00 mg/mL in case of Cu (II) and Fe (III), respectively. The stability of the complexes formed was also studied, and the reaction products were isolated for further investigation. The complexes have apparent molar absorptivities of about 32.14 +/- 0.97 and 168.32 +/- 1.12 for Cu (II) and Fe (III), respectively. The suggested procedures were successfully applied to the analysis of pure etodolac and its pharmaceutical formulations. The validity of the procedures was further ascertained by the method of standard additions, and the results were compared with other reported spectrophotometric methods and showed no significant difference in accuracy and precision.

MeSH terms

  • Absorption
  • Acetates / chemistry
  • Chemistry Techniques, Analytical / methods*
  • Chlorides / chemistry
  • Copper / chemistry*
  • Dose-Response Relationship, Drug
  • Etodolac / chemistry*
  • Hydrogen-Ion Concentration
  • Indicators and Reagents / pharmacology
  • Ions
  • Iron / chemistry*
  • Magnetic Resonance Spectroscopy
  • Metals / analysis
  • Methylene Chloride / analysis*
  • Models, Chemical
  • Models, Statistical
  • Pharmaceutical Preparations / analysis
  • Reproducibility of Results
  • Spectrophotometry / methods*
  • Time Factors

Substances

  • Acetates
  • Chlorides
  • Indicators and Reagents
  • Ions
  • Metals
  • Pharmaceutical Preparations
  • Etodolac
  • Methylene Chloride
  • Copper
  • Iron