High-precision potassium isotopic measurements by collision cell equipped MC-ICPMS

Direct measurement of Fe isotope compositions in iron-dominated minerals without column chromatography using MC-ICP-MS

“…Previous studies found that the matrix effects result from not only the residue cations in sample solutions, but also the dissolved organic material from the resin. Matrix effects and isobaric interference will cause mass bias, such as for the Fe isotope (Schoenberg and von Blanckenburg, 2005; 60 Dauphas et al , 2009; 59 He et al , 2015 63 ), Ti isotope (Zhu et al , 2002 79 ), Mg isotope (An et al , 2014; 80 Bao et al , 2019 73 ), Ca isotope (Bao et al , 2020 81 ), Cu isotope (Zhang et al , 2020 74 ), Zr isotope (Feng et al , 2020 82 ), Ba isotope (Nan et al , 2015 83 ), and K isotope (Li et al , 2021; 84 Chen et al , 2021 85 ). Some matrix elements will not cause isobaric interference, but still can change the instrumental mass bias for Fe isotopes.…”

Precise measurement of 41K/39K ratios by high‐resolution multicollector inductively coupled plasma mass spectrometry under a dry and hot plasma setting

“…Isotopic analysis of K was performed on a Nu 1700 Sapphire MC-ICP-MS housed at the Nanjing University. This instrument is a largegeometry double-focusing mass spectrometer manufactured by Nu Instruments, Wrexham, UK, and contains a 943 mm radius electrostatic analyzer and a 750 mm radius sector magnet, which are the same as the previous model of Nu 1700 MC-ICP-MS. 44 In addition, the instrument is equipped with a double-pass collision cell 35,38 to allow operation in two different modes, which are the "low-energy" mode that involves collision cell and the conventional "high-energy" mode. In this study, the analyses were performed under the high-energy mode.…”

“…Previous studies have demonstrated that K isotope ratio analysis could be affected by mismatch in K concentration between sample and standards 37, but the effect of K concentration mismatch varies greatly between different instruments and laboratories. 35,38,39,41 In this study, we tested the effect of K concentration mismatch on K isotope analysis by analyzing A-K solutions of different concentrations (i.e., 2.1-3.9 ppm, with a 0.3 ppm increment) against a bracketing standard of a 3 ppm A-K solution. The results are presented in Table S3 (supporting information) and Figure 5.…”

“…Two main strategies have been adapted to overcome this obstacle, with the core concept to suppress 40 Ar 1 H + interference. One is to run MC‐ICP‐MS under “cold plasma,” by reducing the forward power of ICP to lower 40 Ar 1 H + production and resolving 40 Ar 1 H + from 41 K + mass spectrometrically 29,36,37,39–41 or correcting 40 Ar 1 H + carefully offline 43 The other one is to perform K isotope analysis on MC‐ICP‐MS that is equipped with collision cell, in which 40 Ar + and Ar‐based interference are removed by collision and reaction with gas molecules such as H 2 and He 6,26,35,38,42 …”

“…33,34 However, the development of high-precision analysis of K isotopes by MC-ICP-MS lagged behind for a decade. 26,29,[35][36][37][38][39][40][41][42] The main challenge in K analysis by MC-ICP-MS is that Ar-based ICP generates intense signals of argon hydrides (e.g., 40 Ar 1 H + ) that interfere with K ions (e.g., 41 K + ). Two main strategies have been adapted to overcome this obstacle, with the core concept to suppress 40 Ar 1 H + interference.…”