A new ideal zircon microanalytical reference material (Tanz) is presented for in situ U–Pb, O and Zr isotope measurements.

Helium (He) is often used as an aerosol carrier gas in 193 nm ArF excimer laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) analysis because it increases the signal intensity compared with that obtained using argon (Ar). In this study, the influence of two carrier gases (He and Ar) on signal intensities was reassessed using a local aerosol extraction strategy and a commonly used cylindrical ablation cell. The experimental results showed that the sampling position in a common ablation cell strongly affected the signal enhancement factors of refractory lithophile elements (Y, Zr, Nb, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf, Ta, W, Th and U) when using He instead of Ar as the carrier gas. The signal enhancement factor of the refractory elements was about 2–3 times in the center position of the common cylindrical ablation cell, which has an ablation location-related carrier gas flow rate of 1.5 m s⁻¹. Enhancement of 3–4 times was obtained at the edge position with an ablation location-related gas flow rate of 0.2 m s⁻¹. Furthermore, the signal intensities obtained using the local aerosol extraction strategy at a sample distance of 1 mm with an extremely high ablation location-related gas flow rate (approximately 10 m s⁻¹) were enhanced only slightly (by approximately 1–1.3 times) for all measured elements when using He instead of Ar as the carrier gas. The similar signal intensities obtained at high-velocity of the carrier gas on the ablation site using Ar as the carrier gas instead of He indicate that the size of the aerosol particles or agglomerates produced by laser ablation decreased considerably as the ablation location-related gas flow rate increased. To gain information on the mechanisms that are involved in the improvement of signal sensitivity by using Ar as the carrier gas at a high-velocity ablation location, a small amount of water vapor was also added into the plasma in both a normal ablation cell and local aerosol extraction strategy. The addition of small amounts of water vapor into the plasma increased signal sensitivity by a factor of 3 using Ar as the carrier gas, while the signal enhancement in wet plasma was about 1.7 fold under a He atmosphere. In addition, similar signal intensities of the entire mass range elements were obtained in wet plasma using Ar and He as carrier gases. These results demonstrate that the difference of elemental signal intensities obtained using He or Ar as the carrier gas can be dramatically alleviated under wet plasma conditions. Our results illustrate that the pronounced enhancement in sensitivity using He as the carrier gas is not only because of the enhanced transport efficiency of small particles, but mostly caused by the more effective vaporization of the aerosol particles in the ICP. Zircon is the most widely used mineral for U–Pb geochronology to provide the timescales, origin and history of rocks. Under wet plasma conditions or with a high ablation location-related gas flow rate, U–Pb age dating of zircon with similar accuracy was obtained using Ar instead of He as the carrier gas.

A novel, fast and simple non-chromatographic approach for determination of inorganic and total mercury has been developed by cold vapor atomic absorption spectrometry based on dielectric barrier discharge (DBD) atomizer. The determination of inorganic mercury and total mercury can be achieved in a fast sequential fashion (1 min sample⁻¹). In the proposed method, with 0.01% (m/v) NaBH₄ used as reductant, inorganic mercury is reduced to elemental mercury, whereas the methylmercury forms an intermediate volatile methylmercury hydride (CH₃HgH). A low temperature DBD atomizer was employed for the atomization of CH₃HgH. Only inorganic mercury can be measured in the absence of the DBD plasma. However, in addition to inorganic mercury, CH₃HgH can be atomized and total mercury is determined in the presence of the plasma. The methylmercury concentration can then be obtained from the difference. The effects of several experimental parameters, such as NaBH₄ concentration, HCl concentration, discharge gas and gas flow rate on the analytical performance were investigated. The method provided good reproducibility (<3% RSD) and the detection limits of Hg²⁺ and CH₃Hg⁺ were found to be 0.35 ng mL⁻¹ and 0.54 ng mL⁻¹, respectively. The proposed method was validated by the analysis of a certified reference material (tuna fish). In addition, it was successfully applied to the analysis of fish samples. The method is excellent for mercury speciation measurements as it provides short analysis time and good reproducibility.

The isotopic composition of sulfur is a vital tracer used in the Earth and planetary sciences. In this study, the laser- and ICP-induced isotopic fractionation in S-rich minerals (sulfides and elemental S) with different matrices was investigated by using 257 nm femtosecond (fs) and 193 nm ArF excimer nanosecond (ns) laser ablation systems coupled to a Neptune Plus MC-ICP-MS. Compared to ns-LA-MC-ICP-MS, higher sensitivity (1.4–2.4 times) under similar instrumental conditions and better precision (∼1.6-fold) under the same signal intensity condition were achieved by fs-LA-MC-ICP-MS. In addition, a fs-laser provides less fluence and matrix dependent S isotopic fractionation, and more stable transient isotopic ratios compared to a ns-laser. Better results acquired by fs-LA-MC-ICP-MS were attributed to the smaller size of particles and less thermal effect produced by using the fs-laser, which were evidenced by the morphologies of the ablation craters and ejected aerosol particles of P-S-1 (the pressed powder pellet of IAEA-S-1) and PPP-1 (a pyrite single crystal from the Sukhoi Log deposit). The ICP-induced isotopic fractionation (matrix effect) was still found in fs-LA-MC-ICP-MS under the maximum sensitivity conditions. However, a significant reduction of the matrix effect was obtained under robust plasma conditions at a lower makeup gas flow rate (0.52–0.54 l min⁻¹) relative to the maximum sensitivity condition (0.6 l min⁻¹) for S isotope analysis. This could be ascribed to the particles that not only pass into the higher temperature ICP for a longer residence time at a lower makeup gas flow rate that resulted in more efficient vaporization of the particles, but also experience a more robust plasma induced by adding 4–6 ml min⁻¹ N₂ into the plasma. Furthermore, under the robust conditions, the results of six reference materials with different matrices obtained by fs-LA-MC-ICP-MS with non-matrix matched calibration with a spot size of 20–44 μm showed excellent agreement with the reference values (the accuracy of 0.01–0.15‰ for δ³⁴S and 0.11–0.45‰ for δ³³S and the precision of 0.16–0.40‰ (2 s) for δ³⁴S and 0.35–0.78‰ (2 s) for δ³³S) and the mass-dependent fractionation line, validating the applicability of the proposed approach for providing high-quality in situ isotope data (δ³³S and δ³⁴S) of sulfides and elemental sulfur at high spatial resolution using non-matrix matched analysis.

In this study, we develop a method for high precision Cd isotope analysis by double spike MC-ICP-MS. Two-step Cd purification using AG-MP-1M resin and TRU resin was used to separate Cd from samples with a recovery of more than 95% Cd and a blank less than 0.1 ng. A practical double spike design and optimization procedure is proposed and the effect of the double spike ratio in the double spike-sample mixture (p) on the measured δ^114/110Cd is evaluated, which broadens the appropriate p range from 0.3–0.6 to 0.1–0.8. In addition, the observed shift/deviation of the measured δ^114/110Cd_{NIST 3108} value from zero-delta due to the change of experimental conditions is discussed on a theoretical basis and a correction approach is developed. Potential Mo and Zr based polyatomic ions have no significant effect on δ^114/110Cd in typical geological samples, while isobaric ions such as Sn, Pd and In can seriously affect the accuracy of measurements even at low concentration. It is shown that the tolerances of isobaric interference can be improved to 0.1, 0.05 and 0.02 for Sn/Cd, Pd/Cd and In/Cd, respectively, after mass discrimination correction. The precision and accuracy of the proposed method were verified by analyzing mixtures of NIST 3108 and a secondary reference material BGEG-Cd of different composition. Long term monitoring of the measured NIST 3108 and BGEG-Cd showed repeatability for δ^114/110Cd of 0.00 ± 0.04‰ and −1.00 ± 0.04‰ (2sd, n = 45), respectively. Finally, we measured Cd isotope compositions of several geological standard materials including soil sediments and manganese nodules, and the δ^114/110Cd values of 0.01 ± 0.02‰ (GSD-5a), 0.04 ± 0.02‰ (GSD-7a), −0.06 ± 0.05‰ (GSD-10), −0.34 ± 0.06‰ (GSD-11), −0.10 ± 0.06‰ (GSD-12), 0.10 ± 0.04‰ (GSD-17), 0.05 ± 0.03‰ (GSD-21), and 0.10 ± 0.07‰ (GSD-23) were in good agreement with the reported values, and a δ^114/110Cd value of −0.08 ± 0.04‰ (GSD-3a) was reported for the first time.

A low power (∼10 W), miniaturized atmospheric pressure glow discharge (APGD) source sustained between a tungsten cathode and a titanium tube anode was coupled with a hydride generation (HG) system for sensitive determination of antimony in water samples with atomic emission spectrometry (AES). Sb ions were converted into volatile hydrides through the reaction with KBH₄ firstly and then were introduced into the APGD source for excitation and detected using a compact CCD (charge-coupled device) microspectrometer. A univariate approach was used to achieve optimized conditions and derive analytical figures of merit. Under optimal conditions, the limits of detection and quantification for Sb were 0.14 and 0.5 μg L⁻¹, respectively. Moreover, the HG-APGD-AES system offered good repeatability (relative standard deviation < 1.5%). The calibration curve was linear in the range between 0.5 and 100 μg L⁻¹, with a correlation coefficient of R² = 0.9996. The proposed method was successfully applied to the determination of certified reference materials (GSB 07-1376-2001, GBW07305a, GBW07307a and GBW073066) and some groundwater samples. Recoveries of Sb added to these water samples were within 90.9–100.7%, proving the good accuracy of the HG-APGD-AES method.