Abstract:Single-cell inductively coupled plasma mass spectrometry (SC-ICP-MS) has been introduced for the analysis of intracellular essential elements and nanoparticles (NPs) at the single cell level. However, it is still quite challenging for accurate and reliable determination. In this work, a high-efficiency sample introduction system was used for single cell analysis with ICP-MS. The system includes a microconcentric nebulizer, a low-volume single pass spray chamber, and a syringe pump. The transport efficiency of single cells was greatly improved to ~12%. In addition, 197Au signals in individual HepG2 cells, after incubation with gold nanoparticles (AuNPs) at the concentrations of 0.1, 0.5, and 1 μM for 12 h, were analyzed by time-resolved ICP-MS with dwell times of 100 μs and 5 ms, respectively. The 197Au signal-to-background ratio (S/B) at 100 μs dwell time was much higher than at 5 ms. For quantitative analysis, AuNP standard reference materials were used for calibration. The SC-ICP-MS data using NP calibration were in good agreement with those using solution ICP-MS analysis, validating the developed SC-ICP-MS method.

Abstract:A recent trend in glow discharge analysis, previously considered as a ‘purely inorganic’ technique, is related to the effective ionisation of volatile organic compounds (VOCs). This approach was demonstrated to be capable of analysing VOCs in both model gas mixtures and ambient air. In the current study, the possibility of the direct determination of VOCs of different classes of organic compounds (including toluene, p-xylene, chlorobenzene and 1,2,4-trimethylbenzene) in ambient air using microsecond pulsed glow discharge time-of-flight mass spectrometry (μs-Pulsed GD TOFMS) with copper hollow cathode was demonstrated. The ionisation processes with the formation of molecular ions M+, which can be used for quantification, were discussed. The fragmentation of detected molecular ions of VOCs was found to be quite low, which benefits both qualitative and quantitative determination. The ease of identification and relative simplicity of the mass spectrum is promising for the analysis of VOC mixtures. One of the possible applications of the designed method is the direct determination of VOCs in human exhaled breath for the diagnosis of lung diseases, including lung cancer. However, revealing its potential applicability for this purpose requires further research.

Abstract:The δ53/52Cr values of twenty-five geological reference materials (GRMs) were determined including igneous rocks, coal, shale, stream/ocean sediments and soils, with high-precision double spike MC-ICP-MS (Neptune Plus). Previously measured GRMs, including MUH-1, OKUM, DTS-2B, and JB-3, were used to monitor the long-term analytical precision and accuracy. The resulting method yielded a long-term precision of ≤ 0.06‰ based on these GRMs, and the δ53/52Cr values were excellently consistent with their previously reported values. Most of the seventeen new GRMs reported here yielded δ53/52Cr values within a narrow range from -0.20‰ to 0.01‰, with an average of -0.14 ± 0.10‰(2SD), which was the same as the unfractionated Bulk Silicate Earth (BSE). However, SCO-2 (shale) yielded a δ53/52Cr value of 0.19 ± 0.03‰ (2SD) and GBW07334 (ocean sediment) yielded a δ53/52Cr value of 0.01 ± 0.05‰ (2SD), which were different from the BSE. Thus, SCO-2 and JH-1 (-0.20 ± 0.02‰) can serve as good candidate GRMs for interlaboratory comparisons.

Abstract:The observation of isotope shifts due to a difference in mass number by diode laser absorption spectroscopy (DLAS) is a powerful approach for the isotope analysis of radionuclides. The spectral resolution for the detection of slight shifts can also be enhanced by a temperature reduction using adiabatic expansion. In our previous studies, we reported that the translational temperature was successfully decreased to approximately 180 K in xenon isotope analysis using a supersonic plasma jet. However, there remains a considerable uncertainty regarding the significant temperature reduction compared with the temperature of argon atoms at the edge of the supersonic plasma jet, which is at 790 K. In this study, temperature differences between two species of three mixed gas patterns (neon/argon, argon/strontium, and argon/xenon) were investigated using low-pressure glow discharge plasma. The temperature differences for the mixed gas patterns were clearly observed and are sufficient evidence to support our previous results. The relationship between temperature differences and energy levels of lower states used as absorption transitions is also discussed.

Abstract:Rice and rice products have been identified as significant sources of As. Concerns have been raised about the presence of As in rice wine. This study collected 79 rice wine samples from China. High-performance liquid chromatography-inductively coupled plasma mass spectrometry was used to determine total As and As species concentrations. The average concentration of total As was 14.6 μg L-1, and the concentration of As (III) (arsenite), As (V) (arsenate), dimethylarsinic acid (DMA), and arsenobetaine (AsB) were 2.86 μg L-1 (0.970–6.08 μg L-1), 7.22 μg L-1 (2.24–22.9 μg L-1), 3.92 μg L-1 (1.58–7.82 μg L-1) and 0.620 μg L-1 (ND-0.950 μg L-1), respectively. MMA (monomethylarsonic acid) and AsC (arsenocholine) were not detected. The THQs (target hazard quotients) for chronic noncarcinogenic risks (skin lesions as the point of departure) were below 1, suggesting that the Chinese population did not encounter a significant noncarcinogenic risk. However, the mean values of MOE (margin of exposure) for lung cancer were below 100 (62.1 to 75.1) for male drinkers, indicating a potential carcinogenic risk. By comparing the As species of rice wines and the main raw material, it was found that the methylation increased DMA during fermentation.

Abstract:Honey is a natural food that is valued worldwide for its nutritional and therapeutic values. Therefore, authentication of honey according to the geographical origin is a guarantee of the genuine properties. In this article, an evaluation of spark discharge-assisted laser-induced breakdown spectroscopy (SD-LIBS) for certification of the geographical origin of honey is reported. Forty-nine samples of multifloral honey produced in four Argentine provinces were considered. The results showed the best classification performance was obtained using smoothing, generalized least squares weighting (GLSW) and mean centering for spectral preprocessing, added to the k-nearest neighbor (k-NN) or Support Vector Machine (SVM) classification algorithms, which provided 100% of correct classification. More importantly, the results of Partial Least Squares – Discriminant Analysis (PLS-DA) pointed to N, Ca, K, Cu, Fe and Mn as key elements for the certification of geographical origin. In addition, the greatest potential of N stands out for the discrimination of the origin of honey. These findings confirm SD-LIBS as a promising tool for authentication of honey quality, providing a simple, fast and environmentally friendly solution. The method can be useful for industry, the market and others related to food authenticity.

Abstract:Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) is an attractive analytical technique for the direct analysis of samples found in the geology, biology, and the environmental and material sciences. However, few reports have discussed the difficulty found in the analysis of curved surface samples by LA-ICP-MS where the main focus is on the curved surface. In this work, LA-ICP-MS was used to map the elemental images of curved surface samples by segmentation and recombination. In addition, the influence of parameters, such as laser spot size, laser fluence, repetition rate, scan speed, dwell time and washout time on lateral resolution were investigated. The developed method was applied to the imaging analysis of lanthanum in an alumina ceramic tube, and the results showed that lanthanum was not uniformly distributed in the tube.

Abstract:Lead (Pb) and cadmium (Cd) are non-essential but extremely noxious metallic elements, and the study of their impact on environmental pollution is of utmost importance. In this report, an economical and environmentally friendly matrix modifier, fluorescent carbon nanoparticles (FCNs), is utilized for the electrothermal atomic absorption spectrometry (ETAAS) determination of trace Pb and Cd in edible salt and soy sauce. FCNs have been characterized for use with UV-Vis spectroscopy, ?uorescence (FL), Fourier transform infrared spectrum (FT-IR) and transmission electronic microscopy (TEM). In comparison to traditional matrix modifiers, FCNs can effectively eliminate matrix interference. Using the proposed FCNs, the ETAAS method achieved a linearity of 10–50.0 μg L-1 for Pb and 0.4–4.0 μg L-1 for Cd; a limit of detection (LOD) for Pb in edible salt of 0.0140 mg kg-1 and in soy sauce of 0.0470 mg kg-1, and for Cd in edible salt of 0.0015 mg kg-1 and in soy sauce of 0.0005 mg kg-1. The method of additions chemical matrix modifier was used for Pb and Cd detection in this study. Excellent accuracy (93.0–101.0% recovery) and precision (0.19–0.85 %) of this procedure were obtained for soy sauce and edible salt. This work provides a new and economical strategy for the determination of trace Pb and Cd and is expected to facilitate future studies in the use of FCNs as a matrix modifier.