The Spectrophotometric Determination of Iron in Solar Salt Samples

Abstract

A method of solvent extraction spectrophotometric determination of trace amounts of iron with 4-capryl-3-methyl-1-phenyl-5-pyrazolone (CMPP) was investigated.
CMPP forms a red stable complex with iron (III) and the reaction product can be extracted in organic solvents. Therefore the reaction is used for the determination of trace iron in solar salt samples.
The proposed procedure is as follows: Sample of 50 g is dissolved in 170 ml of distilled water and adjusted the pH to 3.5 by adding buffer solution of acetic acid-sodium acetate. 6ml of 1-butanol containing 0.3% (w/v) CMPP is added to the solution and the mixture is shaken for 15 minutes. Organic layers is separated from the aqueous phase. After the organic layer is centrifuged for 5 minutes, its absorbance is measured against the 0.3% (w/v) CMPP solution at 450 nm.
It is found out that the solar salt samples used contain 0.2-0.6 ppm iron.