Digestion of Titanium Bearing Geologic Materials Involving Microwaves

An environmentally friendly and rapid digestion procedure involving 10 mL of acid mixture (HNO₃ : HCl : HF = 2:2:1) for 0.1 g of sample in closed vessel microwave digester following heating program : 250W for 10 min., hold time 2 min., 600 W for 17 min, and Ventilation time 10 min was developed. The operating parameters were varied and optimized by factorial design approach using “Steepest Ascent” method. The validity of the recommended digestion procedure were examined by analyzing several well characterized standard reference materials such as diabase (W2), basalt (BIR-1, JB-3, BHVO-1), granite (G2), gabbro (JGb-1), Mn-nodule (Nod-A-1, Nod-P-1), sediment (STSD-4, LKSD-2), limestone (KH-2), soil (SAu-1), ilmenite (IGS-31), rutile (IGS-32), Zircon (IGS-35) and titanium dioxide (SRM-154b) employing both inductively coupled plasma-atomic emission spectrometry (ICP-AES) and well known spectrophotometric method. An excellent agreement between the methods and the certified values of standard reference materials suggest that the digestion procedure can be used for quality control and allied purposes.