Photometric determination of iron in dolomite with Methylxylenol Blue

Abstract

A method was proposed for the photometric determination of iron in dolomite with Methylxylenol Blue (MXB) as a photometric reagent.Iron (III) formed a blue complex with MXB in an aqueous solution of pH 1.41.5. The calibration line followed Beer's low over the range of 540μg/ 25ml of iron (III) at 610mμ.The recommended procedure for iron in dolomite was as follows. A dolomite sample of 0.11.5g the amount depending on the iron content was dissolved in 10ml of hydrochloric acid (1+1) and 1ml of nitric acid, and was heated to dryness on a water bath. The residue was taken up with 25ml of 1N nitric acid and 5060ml of hot water, and the filtrate was diluted to 250ml with water. To an aliquot (510ml) were added suitable amounts of 0.2N nitric acid and 1.0ml of MXB solution, and the mixture was diluted to 25ml with water (the final pH 1.41.5). It was then heated in a water bath of 55±2°C for 3 minutes, and the absorbance was measured at 610mμ against the reagent blank.