Investigating the potential of methyl fluoride cell gas for radionuclide interference removal and measurement using ICP-MS/MS

Inductively coupled plasma tandem mass spectrometry (ICP-MS/MS) has established itself as a valuable analytical technique for measurement of a range of medium- and long-lived radionuclides. The two quadrupole mass filters separated by a collision/reaction cell can achieve online separation of interferences that would otherwise prevent accurate measurement and can be used to support, and in some cases even replace, relatively time consuming offline chemical separation. A number of collision and reaction cell gases have been successfully used for separating radionuclides from interferences, including H2, He, O2, NH3, CH4 and CO2. One gas that has been used for several stable isotopes but never for radionuclides is methyl fluoride (CH3F). This work shows the first investigation of CH3F as a reaction cell gas in ICP-MS/MS for online separation of radionuclides from isobaric interferences. Results are based on a combination of radionuclides and stable analogues along with their isobaric interferences in standard solutions. A range of cell products were investigated, with promising separation schemes for several radionuclides including 59/63Ni, 90Sr and 135/137Cs. The results show the potential to further extend the applications of ICP-MS/MS for radionuclide measurement.