Accurate and Precise Quantification of Arsenic and Selenium in Water and Biological Samples Through the Removal of Doubly Charged Rare Earth Element Interferences by ICP-MS

This month’s column evaluates the capability of inductively coupled plasma–mass spectrometry (ICP-MS) to reduce the impact of doubly charged rare-earth element (REE) interferences on the quantitation of the metalloids, arsenic (As), and selenium (Se) in water and biological matrices. It compares the performance of a number of different interference reduction techniques, including correction equations, and collision/reaction cells (CRC), using various ion-molecule collisional and reaction mechanisms. To identify an optimal method of removal, the authors first assessed the magnitude of interference by individual REEs before comparing the efficacy of their removal with helium as a collision gas and hydrogen, ammonia, and oxygen as reaction gases using different “on mass” and “mass shift” analytical scenarios. Their conclusion was that the only modes to consistently remove REE interferences used oxygen with mass shift, which had better accuracy and lower detection limits for both arsenic and selenium.