Analytical Methods最新文献

Smartphone-based colorimetric sensor arrays using natural dyes are promising for on-site meat freshness assessment, but varying illumination and imaging angles compromise reliability. To address this, we developed an anthocyanin-curcumin array incorporating an α-Fe₂O₃ internal standard and an internal-standard-guided dynamic feature-space switching (IS-DFSS) strategy and validated its effectiveness under complex imaging conditions using ammonia as the representative analyte because it is the dominant component of total volatile basic nitrogen (TVB-N). Eight colorimetric films and the internal standard film were hydrophobically modified and assembled into a 3 × 3 array. The water contact angle increased from 63.3° to 112.9°, ensuring signal stability in high humidity. The sensing units responded strongly to TVB-N components ammonia, trimethylamine (TMA), and dimethylamine (DMA). For ammonia, Euclidean distance increased from 1.23 to 24.7 at 50 ppm and 13.7 to 65.7 at 500 ppm over 120 min, while non-alkaline volatiles (ethanol, hexanal) and non-volatile food matrix components (protein, glucose, fat) were negligible. In pork at 4 °C, array response correlated with TVB-N content (R² = 0.987). The RGB values from 174 ammonia-responsive and 126 environment-interference images were averaged over three replicates to construct datasets, deriving HSV and Lab features. IS-DFSS with CatBoost reduced the mean absolute error to 15.85 ppm (45.46% reduction) and the mean false-signal error to 27.49 ppm (33.97% reduction) versus single RGB features, achieving R² = 0.972. This method provides a robust, portable platform for monitoring TVB-N components, laying the foundation for reliable meat freshness assessment under complex imaging conditions.

Children's toys possess both entertainment value and the core value of promoting children's physical and mental development. However, although children are exposed to volatile organic compounds in a variety of dyes and auxiliaries present on children's toys, the health hazard and the indoor air quality during playtime are poorly known. Specifically, reports on the exposure concentration and potential risk of volatile organic compounds released by children's toys in different timeframes and environments remain scarce. Here, we construct a prediction system for benzene series emission concentration from children's toys by integrating exposure routes, diffusion coefficients and toxicological data using the finite element method. The emission models of the benzene series from different types of children's toys are derived based on Fick's law and Green's function in this paper. The initial release concentration and diffusion coefficient of organic substances in children's toys are obtained through experiments in an environmental chamber and a thermal desorption gas chromatograph-mass spectrometer. Furthermore, an assessment was conducted on the inhalation exposure of different concentrations of toluene and xylene. For the first time, this system converts abstract chemical risks into immersive visual effects through presentation forms such as color and animation. This system achieved dynamic prediction of the spatial and temporal distribution concentrations of different compounds in various scenarios, and it can guide consumers in the use of children's toys and promote technological innovation in the production of children's toys.

Three-dimensional nanoporous PdCe (NP-PdCe) nanocubes were fabricated by dealloying PdCeAl alloy ribbons and integrated with graphene and chitosan to construct an acetylcholinesterase (AChE)-based electrochemical biosensor for malathion determination. The NP-PdCe nanocubes possess a bicontinuous nanoporous framework, mesoporous channels, and exposed Pd-Ce interfacial sites that provide an accessible surface for enzyme loading and promote thiocholine oxidation. Graphene (GR) forms a conductive network for electron transport, whereas chitosan provides a biocompatible film-forming matrix for enzyme immobilization. Under optimized conditions, the AChE/NP-PdCe/GR-CS/GCE biosensor exhibited two linear ranges (2.0-60 and 60-350 ng mL^-1) and a reported detection limit of 1.30 ng mL^-1. The sensor showed acceptable repeatability (RSD 3.35%), fabrication reproducibility (RSD 1.72%), four-week response retention (89.45%), and resistance to selected non-pesticide interferents. In practice, the biosensor was employed to detect malathion in tap water and cabbage samples with satisfactory recovery.

To address the challenges of unstable immobilization of tris(2,2'-bipyridine) ruthenium(II) (Ru(bpy)₃²⁺) and inefficient generation of the tri-n-propylamine radical (TPrA˙) in the Ru(bpy)₃²⁺/TPrA electrochemiluminescence (ECL) system, a novel dual-function strategy using a mixed-valence cerium metal-organic framework (Ce(III,IV)-MOF) was introduced in this study. The Ce(III,IV)-MOF was employed both as a scaffold for Ru(bpy)₃²⁺ and as a co-reaction catalyst. The three-dimensional structure of the Ce(III,IV)-MOF provides a stable environment for Ru(bpy)₃²⁺, while the Ce(III)/Ce(IV) redox pair within the framework facilitates TPrA oxidation through reversible single-electron transfer, thereby enhancing TPrA˙ generation. This design co-localizes the luminophore and catalytic centers within a single framework, reducing shortening the electron-transfer distance between Ru(bpy)₃²⁺ and the TPrA˙ site, and consequently enhancing the ECL performance of the Ru(bpy)₃²⁺/TPrA system. Compared with single-valence MOFs and their physically mixed MOF composites, the ECL performance of the Ru@Ce (III,IV)-MOF/TPrA system is significantly improved, with the maximum ECL signal amplification factor reaching up to 2.7 times. The sensor developed using this strategy showed a broad linear range (1 × 10^-4 ng mL^-1-100 ng mL^-1) and a low detection limit (0.036 pg mL^-1), together with excellent selectivity, stability, and reproducibility. This strategy provides a promising route for constructing multifunctional MOF-based ECL sensors for sensitive tumor biomarker detection.

Microfluidic lab-on-a-chip (LOC) technologies provide a versatile framework for integrating sample handling, chemical recognition, separation, and detection within miniaturized analytical systems. Among their diverse applications, trace-metal analysis provides a particularly instructive model for evaluating the development and practical maturity of LOC technologies because it combines stringent sensitivity and selectivity requirements with complex sample matrices and well-defined analytical and regulatory demands. This review examines the fundamental principles governing LOC platforms for trace-metal analysis and traces the evolution of device design over the past twenty-five years. The historical development of the field is organized into four partially overlapping engineering phases: integrated glass/silicon microfabrication (ca. 2000-2008), PDMS-based soft lithography and rapid prototyping (ca. 2006-2015), diversification toward paper, thermoplastics, and additive or digital fabrication (ca. 2012-2022), and system-level hybrid integration with portable electronics and connected data analysis (ca. 2020-2026). These phases represent shifts in dominant design priorities rather than discrete technological replacements, as earlier materials and fabrication strategies continue to support later-generation devices. Across these developments, LOC platforms are examined through three core functional elements: fluid manipulation, recognition chemistry, and signal transduction. A worked design framework further shows how an analytical problem can be translated into an LOC platform, beginning with the definition of the measurand and sample matrix and progressing through sample preparation, detection, calibration, and validation. The accumulated evidence indicates that sensitivity alone is no longer the principal constraint on progress, since many reported platforms already achieve detection limits below application-relevant thresholds under controlled conditions. More persistent challenges include matrix effects, surface fouling, incomplete sample preparation, device-to-device variability, manufacturing reproducibility, long-term stability, and the limited availability of interlaboratory and field-validation data. The central challenge has therefore shifted from demonstrating feasibility to achieving robust and reproducible performance in complex real samples under realistic operating conditions. By linking fundamental principles with advances in materials, fabrication strategies, detection approaches, and system integration, this review identifies the developments that have shaped the field, the design concepts that have persisted across successive generations, and the unresolved issues that continue to limit translation toward practical deployment.

This Technical Brief reviews the importance of measuring ground level ozone in outdoor air and the challenges of regulating a secondary pollutant formed through photochemical reactions. It describes the principal measurement approach used in air quality monitoring - UV photometric analysis at 253.65 nm. The adoption of a newly recommended ozone absorption cross section value in 2025 is then discussed. This has been derived from a re-evaluation of historical and modern experimental data. This new value is 1.23% lower and with substantially reduced uncertainty when compared with the value previously used. The practical consequences of this change, including higher reported ozone mass concentrations and possible increases in regulatory exceedances, are considered.

Accurate quantification of infant urinary tract infection (UTI)-associated microRNAs remains challenging due to their short length, low abundance, and high sequence homology. Herein, we present a sensitive fluorescent biosensor that integrates a self-priming extension cascade with CRISPR/Cas12a-mediated signal amplification, with the core innovation being a rationally designed ternary sensing probe that consolidates all recognition and amplification elements into a single, self-contained architecture on magnetic beads. This integrated design eliminates the need for multiple exogenously added primers, offering three inherent advantages: fixed stoichiometric ratios ensure reproducible reaction initiation, the unified format simplifies the operational workflow, and stringent coupling of amplification to target recognition suppresses non-specific background. Upon target recognition, the probe undergoes programmed conformational rearrangements that trigger sequential self-priming extension events, simultaneously generating fragments that drive autocatalytic feedback and T7 promoter-containing products for downstream crRNA transcription. The transcribed crRNA activates Cas12a collateral cleavage, producing exponentially amplified fluorescence. Under optimized conditions, the assay achieves a detection limit of 0.48 fM, excellent single-base discrimination, and reliable performance in human serum. Quantification results correlate strongly with qRT-PCR. This exogenously primer-free, self-contained cascade uniquely unifies signal amplification, target regeneration, and crRNA synthesis in a single probe format, while the seamless coupling with CRISPR/Cas12a trans-cleavage ensures both ultrahigh sensitivity and exceptional specificity. The proposed strategy provides a promising platform for early diagnosis and screening of infant UTI.

A novel methylthiazole-quinolinol-based sensor (MTAMQ) named (E)-2-methyl-5-((4-methylthiazol-2-yl)diazenyl)quinolin-8-ol was synthesized. In the presence of copper(II) ions (Cu²⁺), the MTAMQ sensor exhibits a stable color change from yellow to red. The MTAMQ sensor displayed a linear response toward Cu²⁺ ions over the concentration range of 0.10 to 55 µM (0.006 to 3.5 mg L^-1), with a detection limit of 103.93 nM (6.60 µg L^-1). The binding constant of the MTAMQ-Cu²⁺ complex was 1.41 × 10⁴ M^-1, and the stoichiometric ratio of complex formation was 1 : 1. Using EDTA, the MTAMQ sensor can be recycled and reused up to 4 times. Density functional theory (DFT) calculations were conducted for the MTAMQ sensor and the MTAMQ-Cu²⁺ complex. The MTAMQ sensor was successfully used to detect and quantify Cu²⁺ ions in various foodstuff and water samples, and the results were very close to those of the atomic absorption spectroscopy (AAS) method. To enable the detection of Cu²⁺ ions without the need for a complex device, paper test strips were prepared using the MTAMQ sensor and offered successful results. The unique features of the MTAMQ sensor, including naked-eye detection of copper ions in environmental samples without the need for specialized equipment, real-time analysis, cost-effectiveness, simple operation, rapid response, high stability under different conditions, and excellent selectivity and sensitivity, make it a promising alternative to previously reported colorimetric sensors.

Tucatinib is a kinase inhibitor drug used to treat unresectable or metastatic HER-2 positive breast cancer in combination with Trastuzumab and Capecitabine. Forced degradation studies assess the inherent stability of pharmaceutical compounds, while LC-MS/MS facilitates the identification and characterization of the resulting degradation products. In the present study, the stability of Tucatinib (TCB) was investigated under various stress conditions (hydrolytic, photolytic, thermal, and oxidative conditions). It was demonstrated that TCB was susceptible to hydrolytic (acid, base, and neutral) as well as oxidative degradation, yielding 11 degradation products, of which 9 are reported for the first time. A validated UHPLC method was developed using an Agilent Eclipse Plus C18 (4.6 × 150 mm, 5 µm) column with gradient elution using 0.1% formic acid in water and methanol as mobile phases. Mass characterization of the degradation products was carried out on an Exploris 120 Orbitrap mass spectrometer using the same chromatographic conditions. Also, degradation kinetics was assessed to define the trend followed by TCB under different stress conditions. Thus, the present study effectively presents a detailed degradation profile of TCB, and the developed method finds its use for the routine analysis of TCB and formulation development in bulk and dosage forms.

DNA methylation is an important epigenetic modification and has been widely used as a biomarker for disease diagnosis, particularly in cancer screening. However, conventional quantitative methylation-specific PCR (qMSP) often lacks single-CpG-site resolution because the methylation states of neighboring CpG sites within primer or probe binding regions can interfere with amplification efficiency. In this work, we report a novel Hairpin Competition qMSP (HC-qMSP) strategy for precise DNA methylation analysis at single-CpG-site resolution. In this method, degenerate bases were introduced at non-target CpG positions within the primer and probe binding regions to eliminate interference from adjacent CpG sites. Meanwhile, a specially designed hairpin primer was introduced so that the extension product forms a hairpin structure that competes with the reverse primer during amplification, enabling selective amplification of methylated templates while suppressing unmethylated sequences. Under optimized conditions, the HC-qMSP assay achieved a discrimination sensitivity down to 0.1%, and showed good linearity across a wide dynamic range. The method was further validated using colorectal cancer tissues and stool samples, successfully distinguishing cancer samples from normal controls. Owing to its simplicity, low cost, and compatibility with conventional real-time PCR platforms, HC-qMSP provides a promising approach for precise DNA methylation analysis and potential clinical diagnostic applications.