Moment analysis of first absolute (µ1A) and second central (µ2C) moments of elution peaks measured by using high-performance liquid chromatography or capillary electrophoresis is effective for extracting the information about chemical phenomena relating to their separation behavior from equilibrium and kinetic points of view. It is known that elution peak profiles should be integrated to obtain more accurate values of µ1A and µ2C. This means that it is required to appropriately determine the range for integrating the elution peak profiles. Our research group has used a method for determining the start and end points of the integration range. However, it seems that signal noise, baseline drift, and peak asymmetry affects the selection of the integration range and the accuracy in the determination of µ1A and µ2C values of elution peaks. Simulated elution peaks were prepared by adding signal noise of different intensities to a base Gaussian peak and by changing the slope of baseline. Asymmetrical peaks, i.e., tailing and leading, were also prepared by using the Exponentially Modified Gaussian function while changing the degree of asymmetry. The method was applied to choose the start and end points for integrating the simulated elution peaks. Then, the values of µ1A and µ2C were calculated by integrating the simulated elution peak profiles in the integration range. It was tried to clarify how the magnitude of signal noise, baseline drift, and peak asymmetry affect the selection of the integration range of elution peaks and the determination of their µ1A and µ2C values.

Hexavalent chromium (Cr(VI)), a highly toxic and carcinogenic environmental pollutant, poses severe threats to ecological balance and human health. Traditional colorimetric detection methods relying on peroxidase-like nanozymes often suffer from interference caused by reactive oxygen species (ROS) and coexisting redox-active substances, compromising their accuracy in complex water matrices. Herein, we report a novel H2O2-free colorimetric strategy for the ultrasensitive detection of Cr(VI) using atomically dispersed CuCo-NC catalysts. Unlike conventional mechanisms, the synergistic interplay between Cu and Co atoms modulates the electronic structure (d-band center), enabling Cr(VI) to act as a direct electron acceptor. This unique pathway facilitates the oxidation of TMB without generating ROS intermediates, thereby conferring exceptional resistance to common interferents such as Fe[2+]/Fe[3+]. The sensor exhibits a wide linear range (50-1000 nM) and an ultralow detection limit of 1.12 nM, surpassing many existing methods. Furthermore, the practical applicability of this probe is validated through the successful monitoring of Cr(VI) in real water samples (e.g., Guilin Lijiang River), demonstrating its robustness for on-site environmental surveillance. This work not only provides a reliable tool for early-warning monitoring of chromium pollution but also offers mechanistic insights into H2O2-free catalytic pathways.

In the point-of-care, microfluidic, and biochemistry areas, the sample volume is becoming as small as µL order. In this study, we introduce a cyclone concentration pipette that integrates quantitative concentration and sample ejection functions for liquid volume conversion (mL to µL). The concentration pipette is a three-scale polypropylene (PP) tube comprising a cm-scale cyclone concentration chamber, a mm-scale channel for keeping the 10 µL liquid, and a µm-scale orifice (105 µm ± 6 µm) for ejecting liquid. The cyclone concentration system requires continuous observation to determine the endpoint (10 µL). This work introduces an automated control system designed for precise control of a 10 µL volume. The system is built on a Raspberry Pi platform with a Logitech C920 USB camera (1920 × 1080). It monitors the tube in real-time using three parallel detection methods: a convolutional neural network (CNN) for liquid state classification, a MOG2 background subtractor for droplet movement detection, and temporal pixel variance analysis across a 40-frame rolling window for flow state monitoring. When no activity is detected by any method for 30 consecutive seconds, the Raspberry Pi automatically closes a KOGANEI proportional pneumatic valve via a PWM-to-voltage converter (0-10 V). The system automatically terminated concentration without manual intervention. For the water concentration, the mean final volume was 10.6 μL with a standard deviation of 1.65 μL, corresponding to a coefficient of variation (CV) of 15.6% and a bias of + 6.0% relative to the target volume of 10 μL (n = 10). The optimized imaging conditions improved the stability of endpoint detection and volume control, resulting in a final volume of 10.4 μL (CV = 8.2%) with a bias of + 4.0% relative to the 10 μL target, demonstrating acceptable endpoint control accuracy. For the Sunset Yellow solution, a recovery of > 90% and a concentration factor of approximately 90-fold were achieved, indicating that the automated control strategy maintained high sample recovery while achieving efficient concentration.

Reliable fluoride determination in geological materials is often limited by incomplete liberation of structurally bound fluoride and by solution-phase interferences from multivalent cations. In particular, Al and Fe can form fluoride complexes, whereas Ca and Mg may reduce free fluoride through precipitation or association reactions. This work illustrates a Na2CO3-KNO3 alkali sintering method coupled with fluoride ion-selective electrode measurement, in which thermochemical matrix decomposition is combined with citrate complexation, pH-controlled interference removal, and TISAB-based measurement. The method was optimized with respect to flux composition, flux-to-sample ratio, sintering temperature, and pH adjustment prior to TISAB addition. A flux ratio of 2:1, flux-to-sample ratio of 5:1, and sintering at 685 ± 5 [Formula: see text] for 30 min after attaining set temperature provided the most suitable conditions for fluoride recovery during initial optimization. Adjustment of the sample extract to pH ~8.5 after citrate addition improved fluoride recovery by reducing Al/Fe-related complexation, while citrate helped suppress Ca/Mg-induced fluoride loss. After TISAB addition, the final measurement solution was buffered to pH 5.5-6.0. The optimized method gave recoveries in the range of 94-98% for a suite of geological reference materials covering soils, stream sediments, lateritic material, mafic/intermediate rocks, quartz-rich rock, and phosphorites having fluoride concentration in the range of 133 to 40,400 mg kg[-1]. The method LOD and LOQ, estimated from processed blanks, were 15 and 50 mg kg[-1], respectively. The study presents an integrated approach in which fluoride liberation and matrix-interference control are addressed together rather than as separate analytical steps. The present work advances conventional alkali sintering-ISE approaches by integrating Na2CO3-KNO3 assisted fluoride liberation with citrate and pH controlled solution-phase speciation management. This combined strategy enables effective decomposition of diverse geological matrices while minimizing matrix-induced suppression of free fluoride activity, thereby improving the accuracy of fluoride determination across compositionally varied reference materials.

An HPLC-DAD method was established for the simultaneous determination of four synthetic compounds-diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO), Ethyl phenyl(2,4,6-trimethylbenzoyl)phosphinate (TPO-L), (Di-p-tolylphosphoryl)(mesityl)methanone (TMO), and Phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (XBPO)-in nail gel polish, addressing potential safety risks such as sensitization and reproductive toxicity. DFT calculations were utilized as theoretical support to screen extraction solvents by evaluating the thermochemical stability, photochemical stability, and homolysis propensity of target molecules, as well as to determine quantification wavelength under complex mobile phase conditions. For sample purification, a unified QuEChERS procedure utilizing PSA (primary-secondary amine) was optimized, with the aim of removing nail gel polish components that interfere with detection or irreversibly reduce column efficiency. Method validation confirmed satisfactory linearity (R[2] ≥ 0.9999) across specified concentration ranges. Analysis of import and export products revealed detectable levels of at least one of TPO, TPO-L, TMO, and XBPO in 67 samples, which suggests a possible trend: as regulatory bans in the European Union (EU) and other regions came into force, the use of TPO declined, giving way to increased use of the alternatives, TMO and TPO-L, followed by the gradual employment of XBPO in nail gel polish products. Nevertheless, potential risks arising from photoinitiators structurally similar to TPO persist, highlighting the relevance of this reliable analytical approach for cosmetic safety surveillance.

Wearable sweat analysis can extend health monitoring from clinics to daily life. However, sweat is produced slowly and at changing rates, which makes sweat handling difficult. During collection and transport, sweat may remain in the device, flow backward, mix with older sweat, or become contaminated. The liquid that reaches the sensor may therefore differ from freshly secreted sweat. Microfluidic valves can control when sweat moves, where it flows, and how it reaches the sensing region. This review compares five valve classes relevant to wearable sweat systems. They are capillary, Tesla, mechanical, stimuli-responsive, and electro-actuated valves. Each class is assessed in terms of its working principle, flow-control function, power requirement, reusability, suitable task, and practical limit. The comparison covers sweat retention, backflow control, time-separated collection, reagent isolation, and replacement of older sweat at the sensor. The reviewed studies are grouped by tested medium and setting, covering laboratory liquids, artificial sweat, collected human sweat, and direct on-body transport. The main unresolved problems are changing sweat rate, deformation during wear, limited reusability, and unstable materials or interfaces. Solving these problems is important for reliable valve operation during long-term wear.

Rapid identification of male-derived biological evidence enhances forensic casework efficiency, particularly in sexual assault investigations that require prioritization of male DNA for downstream short tandem repeat (STR) analysis. Here, we present an extraction-free direct loop-mediated isothermal amplification (LAMP) workflow targeting the Y-chromosomal sex-determining region Y (SRY) gene for male-specific DNA detection, with the autosomal human leukocyte antigen DRA (HLA-DRA) gene incorporated as a human-specific internal control. Three detection formats were systematically evaluated within a single extraction-free framework: colorimetric LAMP enabled visual SRY detection within 30 min at 65 °C; multiplex real-time LAMP simultaneously detected both SRY and HLA-DRA within 15 min, achieving limits of detection of 100 pg per reaction for male DNA and 10 pg per reaction for total human DNA; and an immunochromatographic strip (ICS)-based format provided instrument-free visual discrimination between male, female, and non-human samples through simultaneous dual-target readout on a single strip. To assess field applicability, five direct lysis reagents were evaluated for compatibility with each detection modality. Nuclease-free water preserved the pH conditions required for colorimetric detection, enabling reliable male DNA identification from whole blood diluted up to 1:25 and saliva diluted up to 1:5. NaOH-based lysis improved DNA release and amplification kinetics in real-time LAMP, enabling detection from blood diluted up to 1:125 and saliva diluted up to 1:625. A UDG/dUTP anti-contamination system was optimized for the ICS format to suppress carry-over-derived false-positive signals while maintaining robust visual band intensity-an essential requirement for reliable point-of-care interpretation. The optimized workflow was validated across multiple forensically relevant matrices including whole blood, saliva, swab-collected samples, and cigarette butt mock evidence, consistently discriminating male- from female-derived biological material. These results demonstrate that direct LAMP, when paired with appropriate lysis chemistry and detection modality, provides a rapid, sensitive, and operationally practical strategy for on-site male DNA screening and forensic evidence triage.

Rhodium is one of the most challenging platinum-group metals to recover by conventional solvent extraction owing to its kinetically inert coordination chemistry. In this study, the extraction of rhodium(III) from hydrochloric acid solutions into neat ionic liquids (ILs) was investigated, focusing on trioctylammonium chloride ([HTOA]Cl), a protic IL designed for anion extraction. To overcome the slow ligand substitution of rhodium(III), the effect of thermal pretreatment of the aqueous phase was examined. Heating a rhodium(III) solution in 8.0 mol dm[- 3] HCl at 100 °C for at least 2 h promoted chloro-complex formation. Subsequent dilution to 1.0 mol dm[- 3] HCl immediately before extraction minimized competitive inhibition by excess chloride ions, enabling efficient anion-exchange extraction. Under optimized conditions, a distribution ratio of 31.6 and an extraction percentage of 97% were achieved at an aqueous-to-IL volume ratio of 1:1. Among several ammonium- and imidazolium-based ILs examined, [HTOA]Cl exhibited the highest performance, demonstrating its suitability for rhodium(III) extraction from chloride media. ESI-MS analysis indicated the involvement of both mononuclear ([RhCl6][3-]) and dinuclear ([Rh2Cl8][2-] and [Rh2Cl9][3-]) chloro complexes, depending on the rhodium(III) concentration. Nearly quantitative back extraction was achieved using 12 mol dm[- 3] HCl. This method enabled selective rhodium recovery from multicomponent hydrochloric acid solutions and was successfully applied to a spent automotive catalyst leachate without requiring additional thermal pretreatment beyond the initial leaching process.

A simplified diffuse reflectance infrared Fourier transform (DRIFT) system using commercial silver powder was investigated as an alternative to previously reported silver colloid/filter-paper systems for infrared signal enhancement. Isonicotinamide, nicotinamide, and nicotinic acid were employed as model compounds to evaluate the spectral behaviour obtained using this simplified DRIFT system. Significant band-dependent enhancement was observed for isonicotinamide and nicotinamide when the samples were subjected to solvent-assisted mixing with silver powder followed by drying. In contrast, simple dry mixing with silver powder produced little or no enhancement, and the control compound nicotinic acid showed no comparable spectral changes. The enhanced spectra exhibited non-uniform increases in band intensity together with peak shifts, band splitting, and changes in spectral shape, suggesting that the observed spectral changes cannot be explained by simple physical mixing with silver powder. The simplified powder DRIFT system enabled observation over a broad spectral region without support-derived absorption and revealed band-dependent infrared enhancement together with peak shifts, band splitting, and spectral shape changes.

Coated-type composite chiral stationary phases (CSPs) based on homosubstituted (same substituents introduced onto the glucose unit) and heterosubstituted (different substituents grafted onto the glucose unit) amylose derivatives were prepared and their enantioseparation capabilities in high-performance liquid chromatography were evaluated. Investigations demonstrated that the enantioseparation capabilities of the composite CSPs generally fell in between those of the two single-component CSPs. Notably, several chiral analytes that failed to achieve resolution on the single-component CSPs were successfully discriminated on the composite ones, thereby extending the application scope of an individual amylose derivative-based CSP. Some anomalous retention and selectivity behaviors were also observed on the composite CSPs, which may be due to some interactions between the two polymers during cocoating. Additionally, the impact of mobile phase composition on enantioseparation was examined. In the hexane/2-propanol (80/20, 90/10, and 95/5, v/v) mobile phase system, a lower 2-propanol content in the mobile phase always results in higher retention factor k1, whereas the separation factor α does not change significantly, with the maximum variation of racemate 2 being approximatley 16%.

A sensitive electrochemical sensor for the detection of methotrexate (MTX), a widely used anticancer and anti‑autoimmune drug, was constructed. MTX monitoring is of great significance for reducing toxic side effects and guaranteeing clinical medication safety. The sensor was based on a glassy carbon electrode (GCE) modified with a nanocomposite of molybdenum disulfide (MoS2) nanosheets loaded with gold gold nanoflowers (AuNFs), followed by the electrochemical polymerization of alizarin red (AR) to form a stable polymeric film (PAR) on its surface. The MoS2 nanosheets were prepared via liquid-phase exfoliation, and the AuNPs were deposited onto them via electrodeposition. The morphology of the modified electrode (PAR/Au@MoS2/GCE) was characterized by scanning electron microscopy (SEM), and its electrochemical properties were investigated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The synergistic effect of the nanocomposite and the conductive polymer significantly enhanced the electrocatalytic activity towards MTX oxidation. Under optimized conditions, the oxidation peak current of MTX at the modified electrode was nearly six times higher than that at a bare GCE. The sensor exhibited a linear response to MTX concentrations ranging from 0.4 to 38.6 µM, with a low detection limit of 0.027µM (S/N = 3). The sensor demonstrated excellent reproducibility, stability, and selectivity. Its practical applicability was successfully validated by determining MTX content in commercial tablet formulations with satisfactory recoveries.

Accurate quantification of pesticide residues is critical to ensure the quality and safety of Rhizoma Polygonati, a well-recognized medicine-food homologous herb widely applied in functional food development. Strong matrix interference in gas chromatography-tandem mass spectrometry (GC-MS) detection and notable quantitative bias are frequently induced by the abundant pigments, polysaccharides, saponins and endogenous components in the herbal matrix. Conventional PSA and C18 adsorbents in standard QuEChERS protocols exhibit restricted purification capacity for this complex matrix, while most documented magnetic carbon-based adsorbents demand tedious pre-synthesis procedures that may block the active adsorption sites of nanomaterials. A modified QuEChERS-GC-MS method coupled with dynamic in-situ assembly strategy was established for 12 pesticide residues in Rhizoma Polygonati. Without pre-synthesis of any composites, in-situ functional synergy between NH2-SWCNTs and magnetic Fe3O4 nanoparticles was achieved during the dispersive solid-phase extraction (d-SPE) step. Superior purification performance to conventional adsorbents was obtained by this system, with the matrix effect range of target pesticides narrowed from -31.4%-64.3% to -25.3%-36.7%. Favorable linearity (R ≥ 0.9990), acceptable spiked recoveries (86.2%-106.5%) and stable precision (RSD ≤ 15.20%) were validated through systematic method validation, providing a feasible and robust analytical protocol for pesticide residue monitoring in Rhizoma Polygonati and other complex herbal matrices.