ABSTRACTAlbiflorin and paeoniflorin are bioactive isomers found in Paeoniae Radix Alba, a key component of Traditional Chinese Medicine. Their accurate and simultaneous quantification is essential for pharmacological research. Standard separation methods often rely on LC‐MS using a mobile phase containing 0.1% formic acid. This study demonstrates that the use of 0.1% formic acid generates a secondary peak for albiflorin that exhibits an identical mass‐to‐charge ratio and similar fragmentation pattern as the main peak. To address this, an LC‐MS method was developed using a Kinetex phenyl‐hexyl column with a gradient elution using a buffered mobile phase of 10 mM ammonium acetate and acetic acid (pH 4.4) in water and methanol. The method was validated for linearity, precision, accuracy, and sensitivity. It successfully separated paeoniflorin and albiflorin preventing the formation of the albiflorin artifact. The method demonstrated good linearity over a concentration range of 1–50 μg/mL. Applicability was tested through the analysis of a Paeoniae Radix Alba extract. The developed LC‐MS method enables accurate and simultaneous quantification of albiflorin and paeoniflorin by eliminating the formation of a second albiflorin peak. This makes the method potentially suitable for pharmacological studies of Paeoniae Radix Alba and other plants containing albiflorin and paeoniflorin.

Selective cleavage of C(OH)-C(OH) bond is crucial for valorization of biomass, waste plastics and other organic compounds, while facing thermodynamic and kinetic barriers. Utilizing active oxygen species (e.g., active hydroxyl (OH*) or lattice oxygen) generated at the anode during water electrolysis provides a sustainable solution to achieve electrochemical activation of the C(OH)-C(OH) bond. However, elucidating the mechanisms of active oxygen species and their roles in enhancing product selectivity remains a challenge. Herein, we report a strategy to unravel the contribution of active oxygen species for C(OH)-C(OH) bond cleavage during alcohols electrooxidation, revealing that lattice oxygen promotes C(OH)-C(OH) bond cleavage and enhances product selectivity. We constructed NiAl-LDH and Ni(Al)-LDH as model catalysts, the latter derived through a "nano-tailoring" Al-leaching strategy. As a result, Ni(Al)-LDH facilitates lattice oxygen formation more readily, which acts as the primary active species for C(OH)-C(OH) bond cleavage and achieves ∼90% selectivity for formic acid production in ethylene glycol oxidation reaction (EGOR). The intrinsic mechanism involves that lattice oxygen participates in EGOR via the Mars-van-Krevelen mechanism and specifically induces C(OH)-C(OH) bond cleavage through an indirect pathway. This mechanistic insight into C(OH)-C(OH) bond cleavage mediated by lattice oxygen provides a valuable reference for designing selective catalysts in alcohols electrooxidation.

Bimetallic SnBi catalyst in metal-organic framework for efficient electrocatalytic CO2 conversion.

The industrial methanol-toluene methylation process for xylene production faces a challenge of lowering the reaction temperature while suppressing the side reaction of methanol to hydrocarbons. This depends on the low-temperature formation of the methoxy intermediate required for methylation. Here, we establish a route for methoxy formation in which formic acid (FA) hydrogenates via a metastable monodentate formate intermediate. With the GaZrOx-ZSM-5 catalyst, Ga-H bonds act as a "placeholder", enabling FA adsorption as a monodentate formate rather than a stable bridged formate. At 300°C and 3.0MPa, toluene conversion reaches 13.9% with 77.6% xylene selectivity, outperforming established routes. Kinetic isotope effect experiments revealed that Ga-based catalysts show a secondary isotope effect, whereas non-Ga catalysts exhibit an inverse isotope effect. Density functional theory calculations indicated that the monodentate formate was more susceptible to hydrogenation which then facilitated methylation. This work provides a competitive route for xylene production from toluene under mild conditions using sustainable FA and H2.

Abstract The industrial methanol–toluene methylation process for xylene production faces a challenge of lowering the reaction temperature while suppressing the side reaction of methanol to hydrocarbons. This depends on the low‐temperature formation of the methoxy intermediate required for methylation. Here, we establish a route for methoxy formation in which formic acid (FA) hydrogenates via a metastable monodentate formate intermediate. With the GaZrO x –ZSM‐5 catalyst, Ga–H bonds act as a “placeholder”, enabling FA adsorption as a monodentate formate rather than a stable bridged formate. At 300 °C and 3.0 MPa, toluene conversion reaches 13.9% with 77.6% xylene selectivity, outperforming established routes. Kinetic isotope effect experiments revealed that Ga‐based catalysts show a secondary isotope effect, whereas non‐Ga catalysts exhibit an inverse isotope effect. Density functional theory calculations indicated that the monodentate formate was more susceptible to hydrogenation which then facilitated methylation. This work provides a competitive route for xylene production from toluene under mild conditions using sustainable FA and H 2 .

Quantitative insight into interfacial solvation remains limited, despite broad relevance to chemical transformations at aqueous boundaries. Here, we employ surface-anchored azide monolayers as molecular probes to quantify and tune solvation at the air-organic-solution interface. The interface is modulated using organic/water mixtures, mixed monolayers containing alcohol surfactants, and solute additives, such as inorganic salts, urea, and formic acid. Among these, water mixtures involving dimethyl sulfoxide (DMSO) or ethylene glycol (EG) prove to be most effective for tuning solvation, establishing design principles for controlling interfacial reactions. Moreover, we map the nonlinear behavior arising from preferential partitioning, one of the invoked explanations for the distinct reactivity at the air-water interface.

Latanoprostene bunod has recently emerged as a promising ocular antihypertensive agent due to its potent ability to lower intraocular pressure and its favorable safety profile observed in clinical trials. In this study, a new, simple, and selective HPLC method was developed for quantifying latanoprostene bunod in pharmaceutical formulations. A Box-Behnken experimental design was employed to optimize the chromatographic parameters, including flow rate, organic solvent, and acid content in the mobile phase. The analysis was performed on an C18 column (4.6 × 50 mm, 3.5 µm), with a mobile phase consisting of water and acetonitrile, both containing 0.01% formic acid (45:55, v/v). Chromatographic conditions were set at a flow rate of 0.6 mL/min, a column temperature of 40 °C, and detection at 260 nm. Method validation, following the ICH Q2(R1) guideline, demonstrated excellent linearity over the concentration range of 0.50–20.00 µg/mL, with LOD and LOQ values of 0.052 µg/mL and 0.157 µg/mL, respectively. Precision and accuracy were confirmed with recovery rates between 100-102% and RSD values below 3%, respectively. The validated method was then successfully applied to the analysis of latanoprostene bunod in a commercially available ophthalmic formulation, confirming its suitability for routine quality control use.

This study centered on creating and validating a UPLC–MS/MS assay that is both reliable and simple, making it suitable for measuring peiminine levels in the plasma of beagle dogs. The established method was then employed with the ultimate goal of elucidating the pharmacokinetic behavior of the compound. The Acquity UPLC BEH C18 chromatographic column was used for separating peiminine and camptothecin (internal standard, ISTD). A binary mobile phase consisting of acetonitrile and 0.1% formic acid in water was used for gradient elution at 0.4 mL/min. In the multireaction monitoring mode, peiminine and a triple quadrupole mass spectrometer with an electrospray ionization source were utilized to monitor peiminine and the ISTD, and detection was performed by monitoring the following transitions: m/z 430.28 ⟶ 412.25 for peiminine and m/z 349.03 ⟶ 305.09 for the ISTD. Results indicated that the accuracy was around 100%, with both interday precision and intraday (RSD) being less than 10.37%. Additionally, a linear response for peiminine was validated over the range of 1–200 ng/mL, with the LLOQ established at 1 ng/mL. In summary, this study perfectly combined the ultrahigh chromatographic separation ability with the ultrahigh sensitivity, selectivity, and structural analysis ability of mass spectrometry, achieving rapid (2 min), accurate, and ultrasensitive (LLOQ 1 ng/mL) analysis of peiminine in samples. Using the developed method, the pharmacokinetic profile of peiminine was successfully characterized in beagle dogs following oral administration.

CO2 capture and utilization require the development of highly selective catalysts that convert low-concentration CO2 into valuable chemicals. Direct air capture (DAC) CO2 contains up to 10% of oxygen as an impurity, which is a sincere competitor to the electrochemical CO2 reduction reaction (CO2RR) due to its favorable thermodynamics. In the best case, the competing O2 reduction reaction (ORR) leads to lower Faradaic efficiencies of the CO2RR, and in the worst case, reactive oxygen species (ROS) are generated that lead to catalyst degradation. To circumvent this competing reaction, a catalyst featuring a kinetic advantage for the CO2RR is required. However, state-of-the-art CO2 reduction catalysts are rarely explored under dilute or impure conditions. Herein, we investigate the intrinsic reactivity of a homogeneous manganese-based CO2RR catalyst under DAC-mimicking conditions. Depending on reaction conditions, the catalyst can follow two different mechanisms, which selectively form either CO or formic acid (FA). The oxygen tolerance of the catalyst was found to be dependent on the reaction mechanism: the first step of the CO selective mechanism is CO2 binding, which is faster than O2 binding, leading to an intrinsically oxygen-tolerant mechanism; however, the formic acid selective mechanism goes via a manganese-hydride intermediate, which facilitates competing ORR at the metal center.

A sustainable room temperature synthesis of ultra-high surface area mesoporous silica material (1653 m2 g−1), designated as QSM-2, has been developed using tetraethyl orthosilicate, cetyltrimethylammonium bromide (CTAB), and β-cyclodextrin (β-CD) as the silicon source, structure directing agent, and additive, respectively. The process was optimised by varying key reaction parameters, including the amount of additive, reaction temperature and sonication, while maintaining a constant silica-to-surfactant ratio. Scale-up studies confirmed reproducibility at a 20-gram scale, highlighting the method's potential for large scale applications. The material with an ultra-high surface area was evaluated for the N-formylation of amines using formic acid as a benign C1 source, thereby enabling the indirect utilisation of CO2. This work presents a sustainable and selective protocol for converting a wide range of amines to the corresponding formamides under mild, solvent-free conditions, achieving excellent yields (up to 99%), and high selectivity (100%).

The acid displacement reaction of formic acid in sea-salt aerosols to release hydrogen chloride is an enigma in atmospheric chemistry: a weak acid transfers a proton to the conjugate base of a strong acid, reversing solution-phase acid-base chemistry. To shed light on this question, we compared the reactivity of formic acid with Na13Cl12 + and Na14Cl13 + under ultra-high vacuum conditions in a mass spectrometer. No reaction was observed with Na14Cl13 +, a known magic cluster that corresponds to a cubic section of the crystal lattice. Na13Cl12 +, which corresponds to the cubic section with a surface defect, reacts readily with release of hydrogen chloride and incorporation of formate into the salt structure. Quantum chemical calculations show that the reaction is substantially endothermic for the magic cluster. The surface defect, however, makes it exothermic. The reason lies in the induced fit of the formate ion in the Na13Cl11(HCOO)+ cluster. Its oxygen atoms interact with five sodium ions. In sum, these electrostatic interactions more than offset the 49 ± 13kJ mol-1 difference in gas-phase acidity between hydrogen chloride and formic acid.

The subsurface sediments of saline-aquatic systems host diverse microbes, with unclear ecological roles and challenging lab cultivability. Chemolithotrophic anaerobes involved in CO2-fixation are one of the poorly studied groups. This study focused on understanding these bacteria from subsurface sediments of four representative saline environments, two marine (i.e., Coastal Arabian and Bay of Bengal seas) and two lake (Sambhar and Lonar) systems through enrichment and metagenomics. Enrichment cultures with bicarbonate/CO2 and hydrogen as the carbon and energy sources, respectively, showed CO2 fixation, producing acetic and formic acids as the major organic products. Enriched culture with Sambhar Lake sediment produced more formic acid (391 ± 8mg/L) than acetic acid (92 ± 20mg/L); however, other enriched cultures produced considerably higher acetic acid (up to 966 ± 24mg/L) than formic acid (up to 367 ± 30mg/L). The organics production was accompanied by unique thread-like (up to 500μm long) aggregates, harbouring chains of rod and oval-shaped microbes in all cultures. Metagenome sequencing revealed dominance of Vibrio spp. (relative sequence abundance of 91% to 97%) across all cultures, while canonical CO2-fixing taxa were nearly absent (< 0.01%). KEGG analysis revealed partial genes for various CO2 fixation pathways, including Wood-Ljungdahl, reverse-TCA, dicarboxylate-hydroxybutyrate, hydroxypropionate bicycle, hydroxypropionate-hydroxybutyrate, and the reductive-glycine pathway. The presence of a near-complete serine variant of the reductive glycine pathway, which has been demonstrated in engineered systems, suggests that this pathway may play an operational role in natural systems. The consistent production of organic acids and incomplete pathway representation suggests modular CO2 fixation within the Vibrio-dominated enriched mixed cultures.

Analytical method validation with development for the detection and quantification of kratom alkaloids using LC-MS/MS.

Altered gut microbiome function in ADHD: More Prevotella, less vitamin B12 biosynthesis, and beneficial modulation by synbiotic treatment.

Determination of residual 15 quaternary ammonium compounds in dairy products by dispersive solid-phase extraction purification with ultra-high performance liquid chromatography-tandem mass spectrometry.

Hair can trace drug use history, but prevailing extraction methods often struggle to fully extract analytes because of tight encapsulation by hair keratin. Since etomidate (ET) was controlled as a Category II psychotropic drug in China in 2023, developing an analytical method to accurately quantify ET and its metabolite etomidate acid (ETA) in hair is essential for establishing cutoff values in hair testing. This study compared extraction efficiencies of alkaline digestion and four solvent-assisted grinding methods (methanol, ammonium formate buffers, 10% formic acid) employing deuterated internal standards (ISs). The optimal method was validated by UPLC-MS/MS and applied to 53 authentic hair samples (11 also analyzed by alkaline digestion for relative extraction efficiency). The ammonium formate-formic acid buffer (pH 3.6) grinding method was proven to be optimal, providing high efficiency while preserving ET stability. It exhibited good linearity (r2 >0.999) in a range of 0.005-5 ng/mg for ET and 0.002-10 ng/mg for ETA. Limits of detection (LOD) for ET and ETA were 0.001 ng/mg, with lower limits of quantification (LLOQ) being 0.005 and 0.002 ng/mg, respectively. All 53 samples had detectable ET (0.013-219.36 ng/mg), while ETA was quantifiable in only 32 samples (0.002-1.873 ng/mg), with ET/ETA ratios of 2.2-615.4. This study establishes a simple, reliable, and validated method for simultaneous quantification of ET and ETA in human hair, demonstrating high practicality for forensic and drug control applications.

Tailoring bifunctional platinum-nickel-carbon catalysts for coupled biomass glucose electrooxidation to value-added products with hydrogen evolution reaction.

A novel method for the determination of dried saliva spots (DSS) based on UHPLC-MS/MS for three α-dicarbonyl compounds: An application in the saliva of diabetes patients.

The utilisation of mono- and bidentate p-cymene RuII-NHC complexes as pre-catalysts, along with formic acid as the hydrogen source, facilitates the formation of active diruthenium intermediates featuring bridging chlorido and/or hydrido ligands, which play a key role in the conversion of levulinic acid to γ-valerolactone.

LC-MS/MS method for quantification of avacopan in human plasma from patients treated for antineutrophil cytoplasmic antibody-associated vasculitis.