Microwave assisted determination of feo in tourmaline

Accurate determination of FeO in acid resistant minerals is impossible by the conventional Pratt's method owing to incomplete sample digestion. Tourmaline is a refractory mineral in which FeO was determined by employing the microwave assisted digestion system for effective sample dissolution and subsequent determination of Fe(II) using redox titration with K₂Cr₂O₇. Conditions such as applied power, ramping time, temperature and hold time during digestion were optimized. The method was validated using a standard reference material. The developed method was successfully applied to tourmaline samples with a standard deviation “d” ≤ 0.27 weight percentage of FeO at different concentration levels.