Analytical Procedures - Iron
February 11, 2002

Introduction

This rapid method of iron determination, is quite suitable for sulphuric acid routine analysis.  It is based on iron-complex formation and its spectrophotometric determination.

Equipment

• Colorimeter
• 100 ml flask

Reagents

• Thioglycolic acid, 10 g/L solution. (Dissolve 10 g of acid with water, in a 1000 ml flask, and make up to the mark).
• Ammonium hydrate

Procedure

Place 50 ml of water in a 100 ml flask, add gently 10 g of sulphuric acid and 5 ml of thioglycolic acid.  After cooling, make a strong alkaline environment with NH₄OH and make up to the mark.  Read this coloured solution in the spectrometer at 530 - 540 nm.

The iron concentration is determined in comparison with a calibration curve, previously plotted with a few iron standard solutions.