⁸⁷Sr/⁸⁶Sr isotope ratios in rocks determined using inductively coupled plasma tandem mass spectrometry in O₂ mode without prior Sr purification

Abstract

Rationale An inductively coupled plasma tandem mass spectrometry (ICP‐MS/MS) instrument can be developed to determine 87Sr/86Sr ratios with an external precision better than 0.05% relative standard deviation (RSD) in “mass shift” mode without prior Sr purification. Previous studies suggested using CH3F, N2O, and SF6 as reaction gases for this method because a better reaction rate can be achieved with Sr+ than with O2 in the reaction cell. However, these gases are not commonly used in general chemistry laboratories, and processes using these gases are difficult to implement quickly due to regulations. We aim to develop a rapid method that can be applied to many samples for the accurate determination of 87Sr/86Sr isotope ratios with precision below 0.1% RSD (or approximately to the fourth decimal place). Methods We evaluated the accuracy and precision of 87Sr/86Sr ratios in certified reference materials and different rock types determined using ICP‐MS/MS with O2 as the reaction gas in comparison with those determined using the multicollector inductively coupled plasma mass spectrometry (MC‐ICP‐MS) method. Results This study showed that by using the ICP‐MS/MS method, the 87Sr/86Sr ratios of BCR‐2 and BHVO‐2 do not vary significantly with and without prior Sr purification; when the Sr concentration of the measured solution is within the range of 60–350 ng/mL, there is no significant effect on the measured 87Sr/86Sr ratios. The results also showed that the 87Sr/86Sr ratios of 23 different rock types measured by ICP‐MS/MS and MC‐ICP‐MS methods agree very well. Conclusions The precision of the 87Sr/86Sr ratio measured using ICP‐MS/MS varies between 0.0001 and 0.0019 (2SD). This precision is less than that of the MC‐ICP‐MS method but is sufficient for certain applications, such as identifying 87Sr/86Sr ratios in different rock types. These results suggest that the developed ICP‐MS/MS method has the potential for future studies involving the identification of Sr sources.

Trends and Advances in Inductively Coupled Plasma Tandem Quadruple Mass Spectrometry (ICP-QMS/QMS) With Reaction Cell

“…Due to spectral interferences, the determination of lower concentrations (ng/mL order or lower) of P, S, Si, Cl, Br, and I is often challenging for traditional ICP-MS. Measurement by ICP-QMS/QMS at massshift mode using O2 as the cell gas permitted a better performance for analysis of these element and has been reported for P, 15,19,34,41,45,[49][50][51][52] S, 15,19,34,40,41,45,[44][45][46][47][48][49][50][51][52] Si, 19,34,45,50,52 Cl, 34,45,52 Br, 34,41 and I, 34,41 respectively.…”

“…Many references used He, H2, O2, or NH3, which are usually included as the default cell gas for ICP-QMS/QMS. 4,22,26,44,46,[62][63][64][65][66] There are also multiple references using N2O, 3,23,28,45,68 CO2, 24,27,65 or CH4 43 as the cell gas to improve the separation of spectral interferences. For single element solution, the typical relative uncertainty of isotopic ratio obtained by ICP-QMS/QMS is roughly in the range from 0.1% to 0.2%, which is inferior to that can be achieved by multiple collector (MC-) ICP-MS by 3 to 4 orders of magnitude.…”

Resolving Severe Elemental Isobaric Interferences with a Combined Atomic and Molecular Ionization Source–Orbitrap Mass Spectrometry Approach: The 87Sr and 87Rb Geochronology Pair

“…Similarly, reactions with O 2 and N 2 O have been employed to address this interference. 11,12 While these methods facilitate the removal of the isobars, quadrupole analyzers do not generally provide the level of precision required for many isotope ratio measurements. 10 While sector-field platforms dominate the field of atomic elemental/isotopic analysis, researchers have also investigated the use of high resolution via FT-ICR 13,14 and Orbitrap 15−17 MS approaches, with the latter being much further developed.…”

“…In this approach, CH 3 F is introduced as the reaction gas in the second quadrupole region to form SrF + , and thus, the Sr determination is performed on the molecular species and the Rb determined for atomic ions. Similarly, reactions with O 2 and N 2 O have been employed to address this interference. , While these methods facilitate the removal of the isobars, quadrupole analyzers do not generally provide the level of precision required for many isotope ratio measurements …”

Erratum: 87Sr/86Sr isotope ratios in rocks determined using inductively coupled plasma tandem mass spectrometry in O2 mode without prior Sr purification

“…In the article by Liu et al, 1 the third named author's given name is spelt incorrectly. The correct spelling of the author's name is Yahui Yue.…”