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

Multielement Principal Component Analysis and Origin Traceability of Rice Based on ICP-MS/MS

In this experiment, inductively coupled plasma tandem mass spectrometry (ICP-MS/MS) was used to determine the content of 30 elements in rice from six places of production and to explore the relationship between the multielement content in rice and the producing area. The contents of Ca, P, S, Zn, Cu, Fe, Mn, K, Mg, Na, Ge, Sb, Ba, Ti, V, Se, As, Sr, Mo, Ni, Co, Cr, Al, Li, Cs, Pb, Cd, B, In, and Sn in rice were determined by ICP-MS/MS in the SQ and MS/MS mode. By passing H2, O2, He, and NH3/He reaction gas into the ICP-MS/MS, respectively, the interference was eliminated by means of in situ mass spectrometry and mass transfer. The detection limit of each element was 0.0000662–0.144 mg/kg, and the limit of quantification was in the range of 0.000221–0.479 mg/kg, the linear correlation coefficient was greater or equal to 0.9987 (R2 ≥ 0.9987), and the detection results had low detection limit and great linear regression. Recovery of the method was in the range of 80.6% to 110.5% with spike levels of 0.10–100.00 mg/kg, and relative standard deviations were lower than 10%. For the multielement content of rice from different producing areas, the principal component factor analysis can get six principal component factors, 87.878% cumulative contribution rate, and the distribution of the principal component scores of each element and different producing areas. Based on the multielement content and cluster analysis, the samples were accurately divided into two major categories and six subcategories according to the places of production, which proved that there was a significant correlation between the multielement content in rice and the place of production, so that the place of rice origin can be traced.

Investigating the feasibility of ICP-MS/MS for differentiating NIST salmon reference materials through determination of Sr and S isotope ratios

Inductively coupled plasma tandem mass spectrometry (ICP-MS/MS) was investigated for possible use in food fraud studies through the measurement of strontium and sulfur isotope ratios. Oxygen mass shift mode was applied to shift ⁸⁷Sr/⁸⁶Sr and ³⁴S/³²S isotope ratios to their respective oxides, ⁸⁷Sr¹⁶O⁺/⁸⁶Sr¹⁶O⁺ and ³⁴S¹⁶O⁺/³²S¹⁶O⁺, effecting a gas-phase chemical separation of the elements from Rb and Kr (for Sr) and molecular N and O species, along with P- and S-hydrides (for S). A total least squares regression approach was employed to generate the isotope ratio data from time-resolved analyses, and method uncertainties and accuracies were determined. The utility of the approach was shown by using the Sr and S isotope ratios together to differentiate between NIST RM 8256 Wild-Caught Coho Salmon and NIST RM 8257 Aquacultured Coho Salmon. These materials are currently under development at NIST as certified food fraud standards and method evaluation materials for comprehensive chemical analysis.

Strategies to overcome interferences in elemental and isotopic geochemical analysis by quadrupole inductively coupled plasma mass spectrometry: A critical evaluation of the recent developments

Quadrupole Inductively Coupled Plasma Mass Spectrometry (ICP-MS) instruments were introduced into geochemical and mineral exploration laboratories nearly four decades ago, providing a technique that could meet their longstanding requirement for the precise and accurate determination of several groups of trace elements and isotopes in geological materials such as rocks, minerals, ores, soils, sediments, and natural water samples. Despite its popularity among geochemists, the technique suffered from spectral and non-spectral interferences some of which seriously affected the quality of the data generated. These interferences have also had a significant impact on the ability of ICP-MS systems to achieve low detection limits. Over the last three decades, technical advances such as the development of high-resolution (HR)-ICP-MS, cool plasma, collision/reaction cell technology (CCT), dynamic reaction cell (DRC) technology, collision reaction interface (CRI), kinetic energy discrimination (KED), tandem mass spectrometry (ICP-MS/MS)/triple quadrupole ICP-MS, and multi-quadrupole ICP-MS have been introduced to eliminate/minimize many of these interferences, with each technique having its strengths and limitations. These technologies have extended the range of elements that can be measured accurately not only in geological materials, but also in several other matrices, with lower detection limits than before. In addition, other methods such as internal standardization, isotope-dilution, standard addition and matrix-matching calibrations have contributed to improving the quality of the data. This paper provides a review of these new developments from the geochemical analysis point of view.