Abstract

A systematic study of the colour reaction formed between iron (llI) and thiocyanate reagent has been carried out by using micro-scale spectrophotometric method. The optimized data resulted conditions in obtaining unusual highest sensitivity with molar absorption of 2.9565x104I/mol.cm at wavelength of maximum absorption 480 nm in 0.2-1.4 N nitric acid medium containing 60% acetone and 25,000 fold molar excess of the thiocyanate reagent. Beer's law is valid for 0.1-4.0 ppm of iron (llI). Sandell's sensitivity is 0.002 μg/cm2. Effects of reagent concentration, order of addition, stability, acidity, types of solvents and diverse ions are reported. It has been found to give accurate results of iron estimations in pharmaceutical preparations and mustard seeds. The proposed optimized method has highest sensitivity, unusual stability and simplicity in operation, without involving cumbersome extractive procedure. Further, the procedure has additional advantages of economy, safety and less time consuming with minimum waste disposal.