Method validation on iron determination by spectrophotometric method in aqueous medium

Rahman, Kazi Moriom; Biswas, Bristy ; Neger, Tahuran ; Sharmin, Nahid ; Rahman, Md. Lutfor


This paper deals with the validation of a method for the determination of iron in spectrophotometric method in aqueous medium. The method is based on complex formation of iron with thioglycolic acid (TGA) in alkaline medium in presence of a masking agent to produce a red purple chelate that has an absorption maximum at 535 nm wavelength. Beer’s-Lambert’s law is obeyed and linear calibration curves were obtained for the concentration range of iron from 0.1 mg/L to 30 mg/L. The reaction is found to be spontaneous in alkaline medium. The limit of detection (LOD) and limit of quantification (LOQ) for the developed method are 0.0108 and 0.0345 respectively. Effect of different parameters like molar ratio of iron to different reagents and interferences, effect of time and effect of temperature of this method of determination were studied. It is found that this method is moderately sensitive and has been successfully applied for the determination of iron (III) in different fields like ceramic materials, clay, sand, glass, stone, soil, water, and any inorganic iron containing compound or alloys. A comparison report is made for Chevron gas field waste material and Certified Reference Material (CRM) of iron, which was done by Atomic Absorption Spectrophotometer (AAS) and Ultraviolet-visible (UV-Vis) spectrophotometer and found to be comparable.


Method validation, CRM, TGA, ammonia, masking agent, percent recovery, precision, LOD and LOQ.

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