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Organisationseinheit der BAM
Isotope analysis plays a critical role in various disciplines, including environmental science, archaeology, and forensic investigations. Traditional methods such as mass spectrometry provide precise isotopic data but often require complex, costly setups and extensive sample preparation. As an alternative, optical spectrometry has emerged as a versatile and less invasive technique. This presentation explores the advancements and applications of optical spectrometry methods in isotope analysis, emphasizing their benefits and challenges.
Lithium (Li), Boron (B), Nitrogen (N), Magnesium (Mg), and Calcium (Ca) are pivotal elements across various spheres such as the hydrosphere, biosphere, and lithosphere, significantly impacting (bio-) geochemical and physiological processes. These elements exhibit stable isotopes with substantial roles in geological, environmental, and biological studies. The traditional method for measuring isotope amount ratios has been through mass spectrometry, which, despite its accuracy, comes with high operational costs, the need for skilled operators, and time-consuming sample preparation processes.
Combining optical spectroscopy with chemometrics introduces an innovative, cost-effective approach by the hand of high-resolution continuum source atomic and molecular absorption spectrometry (HR-CS-AAS and HR-CS-MAS) for the analysis of isotope ratios in Li, B, N, Mg, and Ca. By analyzing the atomic or molecular absorption spectrum of the in-situ generated cloud of atoms of diatomic molecules (e.g., Li, BH, NO, MgF, CaF) during the electronic transition from the fundamental state, this method allows for the rapid determination of isotope ratios directly from sample solutions without the need for complex sample preparation.
For each element, the respective atomic or molecule's absorption spectrum was deconvoluted into its isotopic components using partial least squares regression or machine learning algorithms. Robust calibration models were developed, calibrated with enriched isotope, and validated against certified reference materials. Spectral data underwent preprocessing to optimize the modeling to determine the optimal number of latent variables.
The findings showcase that this optical spectrometric method yields results that agree with those obtained via inductively coupled plasma mass spectrometry (ICP-MS), offering a promising, cost-effective, and rapid alternative for isotope analysis with precisions as low as ± 0.2‰. This approach is a significant advancement in analytical chemistry, providing a new way to study isotope variations in biological, environmental, and geological samples.
What does GD-OES reveal about the aging and manufacturing processes of lithium-ion batteries?
(2024)
Glow-Discharge Optical Emission Spectroscopy (GD-OES), a powerful analytical technique, sheds light on the two critical aspects of lithium-ion batteries (LIBs): manufacturing and aging 1, 2. We optimized cell production in manufacturing by adjusting parameters, including cathode doping, electrolyte concentration, and pressing force. GD-OES provided in-depth elemental composition and homogeneity analysis, which is crucial for identifying optimal manufacturing conditions. These findings were validated by electrochemical impedance spectroscopy, confirming the quality of the manufactured batteries.
Shifting the focus to aging, we use GD-OES for fluorine depth profiling, a key element in understanding polymer and electrolyte degradation. However, fluorine presents analytical challenges. We addressed this by substituting argon with a neon:argon mixture, which significantly enhanced fluorine detection sensitivity. This advancement not only improves accuracy but also holds the potential to guide sustainable and cost-efficient manufacturing strategies.
Through its versatility, GD-OES has proven to be a powerful tool for not only optimizing LIB manufacturing processes but also gaining deeper insights into their aging mechanisms. This research extends beyond academic interest, offering tangible benefits for the industry by translating into improved battery quality, extended lifespan, and overall performance.
In this study, we demonstrate the applicability of nitrogen microwave inductively coupled atmospheric pressure mass spectrometry (MICAP-MS) for Ca, Fe, and Se quantification in human serum using isotope dilution (ID) analysis. The matrix tolerance of MICAP-MS in Na matrix was investigated, uncovering that high Na levels can suppress the signal intensity. This suppression is likely due to the plasma loading and the space charge effect. Moreover, 40Ca and 44Ca isotopic fractionation was noted at elevated Na concentration. Nine certified serum samples were analyzed using both external calibration and ID analysis. Overestimation of Cr, Zn, As, and Se was found in the results of external calibration, which might be resulted from C-induced polyatomic interference and signal enhancement, respectively. Further investigations performed with methanol showed a similar enhancement effect for Zn, As, and Se, potentially supporting this assumption. The mass concentrations determined with ID analysis show metrological compatibility with the reference values, indicating that MICAP-MS combined with ID analysis can be a promising method for precise Ca, Fe, and Se determination. Moreover, this combination reduces the influences of matrix effects, broadening the applicability of MICAP-MS for samples with complex matrix.