Determination of Trace Ti in High Calcium Carbonate Rocks by ICP-MS

The content of Ti in carbonate rocks is generally lower than 3.5mg/g, and most of it is below 1mg/g. X-ray fluorescence spectrometry (XRF), which is commonly used to measure Ti content in silicic rocks (usually more than 0.1%), cannot meet the requirements of accurate measurement of trace Ti in carbonate rocks. This paper reports on the attempts to test Ti in carbonate rock by inductively coupled plasma-mass spectrometry (ICP-MS), discusses and analyzes the interference of 5 test isotopes of Ti (⁴⁶Ti, ⁴⁷Ti, ⁴⁸Ti, ⁴⁹Ti, ⁵⁰Ti) in carbonate solution matrix, and determines the suitable test isotope ⁴⁸Ti. Then the ICP-MS method for the determination of trace Ti in carbonate rock is proposed. According to the method, the concentration of Ti in 5 first-class national standard materials was tested and corrected. The measured values were consistent with the certified values, and the relative standard deviation (RSD, n=10) was less than 7.3%. The concentration of Ti in the unknown carbonate sample solution was measured and corrected under the same experimental conditions, and this method was compared with the national standard method of diantipyrine methane spectrophotometry and inductively coupled plasma-optical emission spectrometry (ICP-OES) method, and the relative standard deviation with these two methods were less than the allowable limit. The recoveries were 83%−107%. This method is suitable for the determination of carbonate samples with 31%−56% CaO and 14−3346μg/g Ti, and provides a reference for the determination of trace Ti in carbonate rocks with high calcium and magnesium.