Project Vienna – Prospects for a novel pre-cell mass filter for MC-ICP-MS/MS using the example of mass-shifted titanium

In recent years the field of ICP-MS/MS has evolved considerably, leading to increased interest in an instrument combining the excellent precision of isotope ratio measurements from multicollector (MC-)ICP-MS with the full analytical versatility of established single-collector ICP-MS/MS instruments.Here, we present preliminary data from Project Vienna.In Project Vienna we created the prototype Thermo Scientific™ Vienna MC-ICP-MS/MS, building upon the experiences collected from the preceding Thermo Scientific Proteus, a one-of-a-kind quadrupole-collision cell-MC-ICP-MS borne from a cooperation between the University of Bristol and Thermo Fisher Scientific™ [1,2].Proteus, although a considerable success, had two disadvantages compared to a conventional MC-ICP-MS: lower sensitivity due to the lower energy extraction of ions from the plasma and the non-exponential mass bias imprinted on the transmitted ions by the quadrupole pre-cell mass filter.In contrast, Vienna retains high sensitivity by using an established MC-ICP-MS interface.The most groundbreaking new feature is the pre-cell mass-filter, which uses combined magnetic and electric fields to select discrete mass ranges in front of the collision and reaction cell.Unlike the quadrupole in Proteus, this technology generates steady and correctable exponential mass fractionation behavior.Titanium isotope measurements are valuable tools in geo-and cosmochemistry.However, isobaric interferences from abundant Ca and Cr make in situ applications challenging.Reaction of Ti + with O 2 proved to be a successful way in moving Ti away from interferents [3,4].The pre-cell mass filter is crucial in this application to clean the mass range (Ni-Zn) of mass-shifted TiO and, additionally, cuts 40 Ca, 40 Ar and 40 Ar 16 O ion beams, which else induce unwanted secondary reactions.The data collected with Vienna can be accurately corrected for mass bias at lower concentrations compared to Proteus, demonstrating the ongoing evolution in MC-ICP-MS/MS.Looking ahead, the collected experience from Project Vienna is being integrated into the MS/MS module for the recently launched Thermo Scientific