Haraguchi K., Sakamoto M., Nagasaka H., Uchida K., Ito Y., Horvat M., Rand M.D., Cirtiu C.M., Yumvihoze E., Kodamatani H., Yamamoto M., Iwai-Shimada M., Duong H.T., Hishida N., Slyadnev M., Begu E., K2026 · 記述言語： 英語 掲載種別： 研究論文（学術雑誌） 出版者・発行元： Analytica Chimica Acta Background: Certified reference materials (CRMs) for mercury speciation of biological fluids have hitherto been limited to frozen or cold-storage types, which impedes the participation of laboratories in tropical or remote regions. Existing CRMs often do not fully meet user needs, particularly regarding storage stability and concentration relevance. Results: Using pooled Japanese human blood, we developed a freeze-dried, ambient-stable blood CRM, with certified values of 6.16 μg L<sup>−1</sup> for total mercury (THg) and 5.46 μg L<sup>−1</sup> for methylmercury (MeHg, as Hg). These concentrations are congruent with median exposure levels in fish-consuming populations (e.g., small island states and riverine Amazonian communities) derived from global biomonitoring data. Homogeneity, stability, and traceability were validated through inter-laboratory comparisons and rigorous uncertainty assessment. Significance: This ambient-stable blood CRM broadens global access to high-quality QA/QC of mercury speciation, especially in regions lacking cold-chain infrastructure. It contributes to capacity building under the Minamata Convention and strengthens interlaboratory comparability. Registration in COMAR and international collaborative deployment are under active development, enhancing the global infrastructure for mercury biomonitoring. DOI： 10.1016/j.aca.2026.345580 Scopus
Kanzaki R., Hidaka T., Tajima S., Kodamatani H., Tomiyasu T. . The “pH-window” of a representative deep eutectic solvent and evaluation of electrodes for pH measurement . Chemical Phys2025 · 記述言語： 日本語 出版者・発行元： Chemical Physics Letters The Brønsted acid–base properties of ethaline, composed of choline chloride and ethylene glycol, were investigated as a representative deep eutectic solvent (DES). Rigorous potentiometric titrations with a hydrogen electrode were performed for the first time in DES to determine the autoprotolysis constant and the p K <inf>a</inf> values of some weak acids. These results revealed a ∼ 4 unit shift in pH relative to water and established the pH window of the DES, which allows direct conversion of the pH value between the DES and conventional solvents. IS-FET and glass electrodes were also evaluated, confirming practical applicability. DOI： 10.1016/j.cplett.2025.142475 Scopus
Kanzaki R., Hidaka T., Kodamatani H., Tomiyasu T., Fujii K. . Proton-transfer reaction thermodynamics in highly concentrated electrolytes for advanced aqueous lithium-ion batteries . J2025 · 記述言語： 英語 掲載種別： 研究論文（学術雑誌） 出版者・発行元： Journal of Molecular Liquids We have studied proton-transfer reactions in highly concentrated aqueous electrolytes focusing on lithium bis(trifluoromethanesulfonyl)amide (LiTf2N) for potential applications in advanced aqueous lithium-ion batteries. In 20 mol kg−1 LiTf2N aqueous solution, the autoprotolysis constant pKW increased significantly to 16.2, indicating a reduction in ionization compared to bulk water (pKW = 14 at infinite dilution), and the H+ concentration is lower than in dilute aqueous solutions. This was mainly attributed to the increase in the activity coefficient of H+ (γH) with increasing LiTf2N concentration. Calorimetric measurements revealed that the increase in pKW is driven by an increase in the autoprotolysis enthalpy, suggesting that H+ is enthalpically unfavorable in concentrated LiTf2N solutions. In contrast, the autoprotolysis entropy showed no significant contribution to the pKW variation. We extended this study to the acid-base reaction of acetic acid as a model system in highly concentrated electrolyte solutions. The pKa value of acetic acid (or the corresponding ionization Gibbs energy) showed little dependence on the LiTf2N concentration. In contrast, the corresponding ionization enthalpy and entropy increased significantly with increasing LiTf2N concentration. Due to the enthalpy–entropy compensation effect, the pKa value resulted in limited variation even under highly concentrated conditions. The obtained enthalpy values for the ionization processes support that proton carriers lie in an enthalpically unstable state. These findings provide new insights into the fundamental behavior of protons in highly concentrated aqueous electrolytes, which is critical for the design and optimization of aqueous lithium-ion batteries and other electrochemical systems. DOI： 10.1016/j.molliq.2025.127388 Scopus
Chang Y.S., Takeuchi H., Kodamatani H., Fujioka T. . Submerged nanofiltration for the removal of perfluoroalkyl substances, N-nitrosamines, and pharmaceuticals and personal care products2025 · 記述言語： 英語 掲載種別： 研究論文（学術雑誌） 出版者・発行元： Separation and Purification Technology Pharmaceuticals and personal care products (PPCPs), perfluoroalkyl substances (PFASs), and N-nitrosamines are contaminants of emerging concern (CECs) in drinking water. The rejection of these CECs by submerged nanofiltration (NF) membrane can vary considerably depending on operating conditions and membrane selection. This study aimed to establish the capacity to predict CEC rejection by four different NF membranes in a submerged configuration. All the NF membranes achieved 40–96 % rejection of uncharged PPCPs with a minimum projection area (MPA) greater than 35 Å<sup>2</sup>. However, the rejection of small and uncharged N-nitrosamines (MPA <25 Å<sup>2</sup>) by the four NF membranes was low (<50 %). Hydrophobic uncharged chemicals showed high rejection (54–99 %) regardless of membrane type. Negatively charged CECs, particularly carboxylate PFASs and PPCPs, exhibited higher rejection (65–99 %) than uncharged CECs, owing to electrostatic repulsion between the membrane and the chemicals. Conversely, positively charged PPCPs exhibited lower rejection (19–96 %) than uncharged CECs because of electrostatic attraction. This study provides a qualitative framework for predicting the rejection of uncharged, negatively charged, and positively charged CECs by different NF membranes at low permeate flux, based on the membrane and chemical properties. DOI： 10.1016/j.seppur.2025.135217 Web of Science Scopus
