Determination of 10 Trace Elements in Kaolin by ICP-MS with Microwave Digestion

Abstract

BACKGROUND As an important aluminosilicate, trace element contents affect the performance of the product. The kaolin standard substances GBW03121, GBW03122, GBW03122a lack the recommended values of ten elements such as arsenic and antimony. Similar rock standard materials were used for monitoring the determination procedure, but the accurate results of the kaolin samples may be affected. OBJECTIVES To establish a method for accurate determination of 10 trace elements in kaolin sample such as arsenic and antimony. METHODS With microwave digestion technology, the nitrate-hydrofluoric acid system and nitrate-hydrofluoric-peroxide system were compared for the procedural heating conditions and dissolution time of microwave digestion. Interference factors of the inductively coupled plasma mass spectrum were also investigated. RESULTS The detection limits of 10 elements were 0.01-0.09mg/kg, and measurement limits were 0.03-0.30mg/kg. The accuracy and precision of the method were directly verified by using rock reference materials. The element recovery was between 90.9% and 103.2%, and the relative standard deviation (RSD) was between 1.2% and 5.8%. At the same time, a comprehensive evaluation of the uncertainty of the method was carried out, and the method was proved to be accurate and reliable. CONCLUSIONS This method has little acid dosage, shortens the measurement time, and reduces the damage on the environment and human, making it suitable for the batch analysis of 10 trace elements in kaolin samples. The method also provides a reference for the determination of the certified values of 10 trace elements such as As and Sb in the national standard material of kaolin.

Keywords

• kaolin
• trace elements
• nitrate-hydrofluoric-peroxide acid dissolution
• microwave digestion
• inductively coupled plasma-mass spectrometry
• kinetic energy discrimination model