Tandem mass spectrometry (ICP-MS/MS) for overcoming molybdenum oxide interferences on Cd determination in milk

It is well known that molybdenum oxides affect Cd determination by inductively coupled plasma mass spectrometry (ICP-MS). It is proposed here a procedure for simultaneous determination of Cd and Mo. The effectiveness of the ICP-MS with tandem configuration (ICP-MS/MS) using octopole reaction system (ORS3) pressurized with oxygen gas and MS/MS mode to overcome Mo oxide-based interferences on Cd determination was evaluated. Cadmium was determined as free atom ion and Mo was determined as MoO2+ employing a 0.5 mL min(-1) oxygen gas flow rate into the ORS3. Non-fat and whole milk powder certified reference materials (NIST SRM 8435 and SRM 1549) were used for checking the accuracy of the proposed procedure. The microwave-assisted digestion was carried out using diluted nitric acid solution (2.6 mol L-1 HNO3) and hydrogen peroxide (30% m m(-1)). According to Student's t-test, reference and determined values were in agreement at a 95% confidence level, except for Cd-111 and Cd-113 in SRM 1549. (C) 2015 Elsevier B.V. All rights reserved.