Journal of Analytical Atomic Spectrometry最新文献

Using inductively coupled plasma mass spectrometry (ICP-MS), we have measured the elemental concentrations of Na, Fe, Cu, P, Mg, Zn, K in plasma samples of 25 Alzheimer's disease (AD) patients and 34 healthy individuals. Given the multidimensional nature of the ICP-MS data, we used support vector machines and logistic regression to illustrate the elemental distribution of each donor and seek key features that may differentiate plasma samples of AD patients from those of healthy individuals. We found that ratios of the elemental concentrations of Na over K, Fe over Na, and P over Zn yield specificity, sensitivity, and accuracy of 79%, 84% and 81% respectively. This information was then used to seek from the mass spectrometric data a differentiation of the plasma samples from AD and healthy donors. Plotted as a function of the Na/K, Fe/Na, and P/Zn, the ICP-MS data reveals a linear delineation between the two groups of samples yielding to the correct classification 21 of 25 AD and 28 of 34 HC plasma samples. These findings highlight the importance of elemental ratios present in plasma and suggest that the ratios of the elemental concentrations of blood metals may be considered as biomarkers that can distinguish plasma samples of AD patients from healthy subjects.

Chalcopyrite has been extensively utilized for tracing geological processes through its Cu, Fe and S isotopic compositions. However, the matrix-matched reference materials for micro-analysis are lacking. This study focused on assessing the feasibility of a natural chalcopyrite specimen (IGGCcp-1) as a matrix-matched reference material for in situ micro-analysis of Cu, Fe, and S isotopes. Electron probe microanalysis validated the uniform distribution of major elements within chalcopyrite grains, with no evidence of growth zoning. Random spot isotopic measurements using LA-MC-ICP-MS demonstrated remarkable consistency in δ⁶⁵Cu, δ⁵⁶Fe and δ³⁴S. These results indicated that the IGGCcp-1 specimen exhibited its suitability as a reference material. Using SN-MC-ICP-MS technique, the δ⁶⁵Cu value was accurately determined to be 0.43 ± 0.05‰ (2S, N = 30). Furthermore, the δ⁵⁶Fe_IRMM-014 and δ⁵⁷Fe_IRMM-014 values were recorded as −0.24 ± 0.04‰ (2S, N = 18) and −0.36 ± 0.09‰ (2S, N = 18), respectively. Additionally, the δ³⁴S_VCDT measurement, performed with EA-IRMS, yielded a value of −0.28 ± 0.60‰ (2S, N = 10). These precisely measured isotope ratios established the recommended reference values for the IGGCcp-1 sample in future applications of Cu, Fe, and S isotope micro-analysis.

In this work, a highly sensitive procedure for the determination of mercury in flue gas was developed, based on direct-current atmospheric pressure glow discharge in hydrogen and helium (H₂–He) atomic emission spectroscopy (APGD-AES) coupled with gold amalgam enrichment (GA). Calibration mercury vapors generated by the cold vapor generation (CVG) system were sent to the GA system for enrichment. Subsequently, mercury was thermally desorbed and transmitted to APGD for excitation, and at the same time, the signal at 253.6 nm was recorded using a micro-spectrometer. The parameters of GA and APGD systems were optimized, including the type and flow rate of the carrier gas, discharge current and discharge gap. Under the optimum operating conditions, when the sampling volume of the flue gas was 10 L, the detection limit (DL) of Hg was 0.1 μg m⁻³, which met the actual measurement requirements, and the relative standard deviation (RSD) was 2% (n = 11), the linear correlation coefficient was better than 0.999. The accuracy and practicality of GA-APGD-AES were verified by the analysis of flue gas. The results were consistent with those of a direct mercury analysis (DMA) system (n = 3, relative deviation was less than 3%).

Multi-channel dilution analysis (MCDA) is a new calibration method that performs multiple dilutions of a standard solution as it makes its way from an autosampler to an analytical instrument. MCDA is based on the standard dilution analysis (SDA) method that combines the traditional standard additions and internal standardization calibration methods, correcting for both matrix interferences and fluctuations in signal levels associated with variations in the sample environment. Analysts operate the instrument in the normal manner, as all dilutions are performed automatically by splitting the sample stream entering the instrument into multiple channels of different tubing diameters and lengths. This setup results in a signal “stairstep” as portions of solution are measured at different points in time. A calibration curve is prepared from the plateau regions of the signal stairstep. MCDA has been exhibited using inductively coupled plasma optical emission spectrometry, which is a workhorse for the determination of trace metals in solution. However, MCDA is applicable for any analyte of interest in any sample type, as long as the selected measurement technique accepts samples as a flowing liquid stream. MCDA is applied to the analysis of three certified reference materials by inductively coupled plasma optical emission spectrometry (ICP-OES). Percent recoveries for a suite of analytes range from 87–106%, with relative standard deviations on the order of 1%. MCDA simplifies the analysis process, increasing sample throughput by significantly decreasing the time required for solution preparation.

The quality control (QC) of an analytical method for any analytical data measurement depends directly on the matrix matching standard and certified reference material (CRM). In many cases, obtaining a matrix match standard and an RM or CRM as a control sample in sufficient amounts for QC analysis is difficult. It is also not advised to use a CRM as a standard for routine analysis owing to its high cost and availability in lower quantities. In view of this, in-house reference standards/materials for isotopic compositions of boron (IC, ¹⁰B/¹¹B atom ratio) in natural and enriched boron carbide matrix were prepared in the present work. These in-house reference standards/materials will be helpful for method validation, quality control and quality assurance in the IC determination of boron carbide samples using particle induced gamma-ray emission (PIGE) method. A total of five different isotopic compositions, namely natural (19.8 atom% of ¹⁰B) and 30, 40, 50 and 67 atom% of ¹⁰B-enriched B₄C, were prepared in sufficient quantities (0.8 kg each). Homogeneity and stability tests were performed for the prepared materials with respect to their isotopic composition by analysing direct powder samples using the external PIGE method, and they were found sufficiently homogeneous and stable for the property value for use as in-house reference standards. Assigned values of isotopic compositions were determined through external PIGE using both powder and pellet samples. The obtained values of the isotopic compositions are 0.247(1), 0.427(2), 0.662(3), 0.991(4), and 2.028(7) for the natural and 30, 40, 50 and 67 atom% of ¹⁰B-enriched boron carbide, respectively.

Nanoparticles (NPs) are ubiquitous because they find applications in nanomedicine, materials science, and consumer products to name a few, and eventually end up in the environment. The various techniques available to analyze NPs each have strengths and limitations. This study focuses on improving the single particle inductively coupled plasma mass spectrometry (spICPMS) technique to address the limitations of existing methods and improve the size detection limit for Pt and Au NPs. Infrared heating of the spray chamber and connection to the torch is used to pre-evaporate the aerosol and improve the transport efficiency. Eight modified cyclonic spray chambers with a volume ranging from 25 to 125 mL, where an IR emitter is inserted in a modified baffle and the gap between the top of the baffle and the top service of the spray chamber was varied, are tested for the characterization of NPs to see their effect on sensitivity, detection limit, and transport efficiency. The results indicate that the 50 mL modified spray chamber with a 2 mm gap between the top of the baffle and the top service of the spray chamber offers the best detection limit for Pt. It enhances sensitivity and precision and allows accurate characterization of Au and Pt NPs without any measurement of the transport efficiency. Furthermore, this sample introduction system provided similar improvements in sensitivity and detection limit when used with the same nebulizer on two different spICPMS instruments.

The most used international reference material for neodymium isotope ratios is the JNdi-1 standard. The literature reference values were determined using Thermal Ionization Mass Spectrometry (TIMS) with a conventional internal normalization. In nuclear studies, such normalization is not possible for samples after irradiation, as there is no known isotope ratio that can be considered as a reference ratio. Nd isotopic analysis is essential for calculating the burnup of a reactor. To offer reference values without normalization, 61 measurements of the JNdi-1 material were obtained in three different laboratories on four thermal ionization mass spectrometers using the total evaporation method. Acquired measurements were compared to the exponential mass fractionation law demonstrating that the dominant bias comes from isotope fractionation which can be minimized using the total evaporation method. The suggested reference values and associated uncertainties with a coverage factor of 2, which indicates approximate 95% confidence, were calculated using the DerSimonian–Laird procedure (n = 3): ¹⁴²Nd/¹⁴⁴Nd = 1.13966(23), ¹⁴³Nd/¹⁴⁴Nd = 0.511613(50), ¹⁴⁵Nd/¹⁴⁴Nd = 0.348729(33), ¹⁴⁶Nd/¹⁴⁴Nd = 0.72329(15), ¹⁴⁸Nd/¹⁴⁴Nd = 0.242505(95) and ¹⁵⁰Nd/¹⁴⁴Nd = 0.23780(14). All these ratios are significantly different from those obtained after normalization using ¹⁴⁶Nd/¹⁴⁴Nd = 0.7219. The new values obtained for the JNdi-1 can be used in nuclear laboratories where the Nd isotope ratios differ from the natural isotopic compositions or when the total evaporation method is used without internal normalization.

In situ microanalysis of the sulfur (S) isotope composition and elemental distribution in sphalerite is important in geochemistry. A matrix-matched reference material is still lacking in situ microanalysis. In this study, a hydrothermal synthesis method combined with hot-press sintering processes was used to synthesize a sphalerite material Sph-LD. A large number of in situ microanalyses, including trace element concentrations and S isotope compositions, were performed on Sph-LD by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) to assess the homogeneity. The LA-MC-ICP-MS results are highly consistent and yield a mean δ³⁴S value of +17.11 ± 0.20‰ (2 SD, n = 560), which is analogous with that measured by IRMS. Microanalysis of element concentrations generally agrees with the data of ICP-MS within 10% for trace elements (relative standard deviation < 10%). These results indicate that Sph-LD is suitable to be a matrix-matched reference material available for quantitative analysis of element concentrations and S isotope measurement of sphalerite using LA-ICP-MS and LA-MC-ICP-MS. Meanwhile, the synthetic method introduces a novel concept for the development of standard materials.

Three-dimensional chemical imaging by XRF spectrometry techniques continues to advance in both experimental methods and quantitative data evaluation and reconstruction strategies. These techniques are gaining interest across various research fields, ranging from material science and environmental and Earth sciences to life science and biomedical imaging. Two primary techniques associated with 3D XRF spectrometry are reviewed in this update: XRF spectrometry CT and confocal XRF spectrometry. There has been an increase in the building of in-house specialised 2D XRF spectrometry instruments. Attention to various components, e.g. coating of optics, has improved performance. There was an increase during the review period in the use of SR-XRF spectrometry in conjunction with complementary X-ray spectroscopic and imaging techniques for integrating spatially resolved elemental data with information on speciation and structural and morphological images. Applications of μXRF spectrometry continued to expand in fields such as biomedical, environmental and materials sciences and cultural heritage research. These applications were primarily carried out at specialised hard-X-ray micro- and nano-probe facilities by combining SR-XRF spectrometry with micro- and nano-XAS, XRD analysis, ptychography and various forms of tomographic techniques. The TXRF spectrometry technique continues to be successfully implemented in medical research because of its outstanding performance as a microanalytical method. Changes in the elemental profiles of small organs from, e.g. rats, can be detected. The introduction of a versatile pipetting instrument made possible significant advances in the strategic identification of errors in sample morphology. MacroXRF spectrometry continues to play a significant role in cultural heritage applications. Instrumentation is constantly expanding with new functionalities such as simultaneous measurement with reflectance image spectroscopy and luminescence imaging spectroscopy. The investigation of papyrus fragments was enhanced by upgrading a novel mobile macroXRF spectrometer scanner with new high-performing mechatronics and a high-throughput detection system.