Critical reviews in analytical chemistry最新文献

Silver-doped layered double hydroxides (Ag-LDHs) have gained prominence as a high-performing class of electroactive materials suited to advanced electrochemical sensors, exhibiting remarkable sensitivity, selectivity, and long-term stability in environmental, biomedical, and food analytical settings. Silver incorporation not only narrows the band gap of the LDH host but also endows the heterostructure with enhanced electrical conductivity, surface reactivity, and rapid redox cycling, clearly outpacing both pure and conventional-metal-doped LDH architectures. These hybrids utilize the inherent ion-exchange capacity and extensive surface area of LDHs, further enhanced by integration with functional materials such as carbon allotropes, metal oxides, and conductive polymers, leading to a synergistic improvement in electrocatalytic performance and mechanical resilience. Despite several studies on these composites, a comprehensive study that critically compares structural designs, synthesis methods, and functional performance in electrochemical sensing is absent. This article addresses that gap by providing a systematic, side-by-side comparison of contemporary Ag-LDH synthetic routes, surface-modification protocols, and sensing metrics. Application-centric evaluations encompass the quantification of pollutants in aqueous matrices, the diagnosis of disease-relevant biomarkers, and the deterrence of unsafe food items. Enduring barriers, including the scale-up of manufacture with consistent quality, stability over extended operational lifetimes, and the realization of cost-competitive fabrication, are rigorously appraised alongside prospective pathways, such as eco-conscious synthesis protocols, hybrid nanoscale architectures, and machine-learning-augmented ideation of sensor designs. Collectively, the compiled findings furnish a coherent roadmap for the translational maturation of Ag-LDH-based electrochemical sensing technologies that transcend proof-of-principle and advance toward the reliable point-of-care deployment beyond controlled laboratory environs.

Gallstones are crystalline bodies with a heterogeneous composition in relation to the type, mainly categorized as cholesterol, pigment, or mixed stones. Their physicochemical properties need to be identified to make appropriate diagnoses, establish effective treatments, and implement sound prevention measures. This review has gathered a comprehensive set of techniques applied to characterizing gallstones. Spectroscopic techniques including Fourier-transform infrared (FTIR), Raman, and Ultraviolet-visible spectroscopy (UV-Vis) spectroscopy provide crucial functional groups and molecular structures and identify organic constituents such as cholesterol, bilirubin, and calcium bilirubinate etc. Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) and Laser-Induced Breakdown Spectroscopy (LIBS) deliver surface-sensitive elemental information, in the case of TOF-SIMS especially, to trace metals such as Fe, Cu, Zn, as well as contaminants like Pb and Cd. The thermal techniques like Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) extract differences in cholesterol content and heat stability between the different categories of stone. Complementary methods like X-ray diffraction (XRD) and scanning electron microscopy (SEM) dissect mineral phases and surface topography. Differential elemental quantitation with inductively coupled plasma optical emission spectroscopy (ICP-OES) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) determines Ca, Mg, and Fe to be major contributors to the development of gallstones. This review highlights the diagnostic value of elemental signatures, crystalline morphology, and thermophysical transitions in determining gallstone ethology and composition and help us in dealing with pathogenesis, with multi technique combination providing the most comprehensive description. Finally, the integration of analytical methods provides a solid basis for clinical and research gallstone analysis.

The increasing popularity in recent years of oral smokeless products (OSPs) and heated tobacco products (HTPs) has raised significant public health and regulatory concerns. Although these products are often marketed as less harmful alternatives to traditional cigarettes, they differ considerably in both design and, more importantly, in their chemical composition. Notably, they contain potentially dangerous compounds such as tobacco-specific nitrosamines, flavorings, heavy metals, and nicotine, which can be addictive and harmful to human health at certain concentrations. This work provides an overview of the analytical techniques and methods used to analyze OSPs and HTPs, including the determination of moisture content and pH, the extraction of various compounds, the generation of HTP aerosol, and non-targeted analysis, as well as the quantification of extracted compounds using gas chromatography, liquid chromatography, and spectroscopy. Identifying and quantifying the chemical composition of OSPs and HTPs is essential for assessing their health impact and developing proper regulatory standards regarding these products.

The clinical and laboratory diagnosis of diseases caused by parasites - helminths and protozoa - presents several limitations. To solve these gaps, new technologies have been developed. Metabolomics is in the spotlight due to its potential for discovering biomarkers that can be useful in the clinical laboratory. In this systematic review, we evaluate the main biomarkers identified in parasitic infections by metabolomics and the perspectives for their use in the clinical laboratory. The search was conducted on PubMed, SciELO Brasil and LILACS-Bireme platforms with the combination of descriptors "metabolomics" and "parasites" or "helminth" or "protozoan". A total of 65 studies met our eligibility criteria. Plasmodium spp., Toxoplasma gondii and Schistosoma spp. were the most studied parasites. Experimental infections were more commonly performed, indicating that metabolomics is in the process of being standardized for its application in laboratory routine. Among all metabolites, amino acids were the most commonly observed in parasitic infections. In the context of metabolite detection, the majority of studies employed mass spectrometry (MS), whereas only a limited number utilized nuclear magnetic resonance (NMR) spectroscopy. The main advantage of employing metabolites in diagnostics is their early detectability, overcoming limitations imposed by the parasite's life cycle and excretion dynamics. We demonstrate the potential of metabolomics tools as alternatives to complement the conventional parasitological diagnosis.

Benzene (Bz), phenol (Phen), hydroquinone (HQ), and catechol (CAT) are volatile organic compounds (VOCs) (monoaromatic compounds) considered environmental contaminants as a consequence of human and industrial activities. Prolonged exposure affects human health, causing cancer and death. Researchers have developed and applied analytical methodologies in pretreatment samples and detection techniques to analyze these monoaromatic compounds at trace and ultra-trace concentration levels. The present study is focused on an in-depth review and comparative analysis of removal and extraction techniques, summarizing the sources (analytical matrix), interaction modes (analyte-sorbent) in extraction techniques, solid phase extraction (SPE), dispersive solid phase extraction (DSPE), magnetic solid phase extraction (MSPE), and microextraction techniques), and the determination methods (chromatographic and non-chromatographic) applied in the analysis of these monoaromatic compounds in complex matrices.

An essential excitatory neurotransmitter and metabolic intermediary, L-glutamate is vital for multiple physiological functions, such as memory, learning, and synaptic transmission. A variety of neurological and neurodegenerative conditions have been attributed to aberrant glutamate levels, emphasizing the significance of reliable and continual monitoring in biological systems. Despite their remarkable sensitivity, classical analytical techniques are sometimes compromised by intricate procedures, outrageous expenses, and constrained applicability for point-of-care applications. However, enzymatic electrochemical sensors exhibit higher selectivity; their high production costs and inconsistent functioning make them impractical for long-term use. Nonenzymatic electrochemical sensors, on the other hand, have become a viable alternative due to their superior stability, cost-effectiveness, and ease of manufacture. Recent advancements in nonenzymatic glutamate sensors are thoroughly investigated in this review, with a focus on innovative material strategies that enable enhanced sensitivity, selectivity, and detection limits over a wide concentration range. The aforementioned strategies comprise metal and metal oxide nanostructures, carbon-based platforms, and hybrid composites. It also explores substantial breakthroughs in sensor architecture, operation, and practical applications in intricate biological matrices. These enzyme-free systems' expanding prominence in contemporary biosensing technologies is illustrated by their promise in therapeutic diagnostics, neurochemical research, and point-of-care testing.

Lysergic acid diethylamide (LSD) remains a significant forensic and public health concern due to its widespread abuse and association with drug-facilitated crimes. Detecting LSD and its analogs in biological specimens, particularly postmortem matrices, presents analytical challenges stemming from its low dosage, rapid metabolism, and structural similarities to novel lysergamides. This review critically examines trends in validated analytical methods for LSD detection in forensic toxicology. A systematic review of literature from 1978 to 2025 was conducted using databases, such as PubMed, ScienceDirect, and Google Scholar. The analysis focused on reported methodologies for LSD and its metabolites across various matrices, including blood, urine, hair, oral fluid, and vitreous humor. Extraction techniques (LLE, SPE, DLLME) and analytical platforms (GC-MS/MS, LC-MS/MS, CE-MS) were compared, with emphasis on validation parameters, such as sensitivity, specificity, recovery, LOD, LOQ, matrix effects, and stability. The review identifies LC-MS/MS as the most sensitive and widely validated technique; however, discrepancies remain in matrix-specific validations and stability assessments. Challenges include the lack of certified reference materials for LSD analogs, matrix-dependent degradation, and limited methods for emerging sample types, such as dried blood spots (DBS). Few studies fully comply with modern forensic validation guidelines, limiting the reproducibility and admissibility of results in legal settings. This review highlights critical gaps in current forensic LSD detection protocols and underscores the need for standardized, validated methods applicable to diverse matrices. Future research should prioritize the development of rapid, eco-friendly, high-throughput methods capable of detecting LSD and its analogs at ultra-trace levels.

Micelles, formed from surfactants, offer alternative media for separation and detection techniques, addressing challenges such as sample complexity, method sensitivity and selectivity, analysis cost and time, and environmental impact. The critical micelle concentration (CMC) plays a pivotal role in micelle formation, with normal and reverse micelles being the main structures observed. Additionally, niosomes and liposomes contribute to sample preparation methods. Polymeric micelles exhibit a core-shell configuration, allowing for modification of their properties. Micellar systems find application in various techniques, including cloud point extraction (CPE), coacervation extraction, microextraction, and supercritical fluid extraction. CPE offers environmentally friendly and cost-effective extraction, enhancing analyte solubility and detection limits. The review further discusses the applications of micellar systems in CPE, including the analysis of hazardous organic impurities and the purification of biological compounds. Metal-CPE is explored as a method for extracting organically chelated metals. The utilization of micellar systems in sample preparation showcases their potential in improving analytical methodologies.

Alkaloids represent one of the most significant classes of compounds of natural and synthetic origin due to their pronounced biological activity and broad applications in pharmacy, medicine, and toxicology. Their determination in complex matrices such as biological fluids or pharmaceutical formulations necessitates the use of highly sensitive, selective, and reliable analytical techniques. Among these, electrochemical methods, particularly voltammetry, provide rapid, cost-effective, and precise detection. This review systematically evaluates voltammetric approaches for the determination of alkaloids and their metabolites, with a particular focus on studies published over the last two decades (2005-2025). More than 90 publications have been critically analyzed, covering voltammetric methodologies applied to 26 alkaloids and their metabolites, and highlighting key trends in electrode selection, experimental conditions, and strategies to enhance analytical performance. Special emphasis is placed on linking the electrochemical behavior of alkaloids to their chemical structure and functional group affiliation, providing insights into reaction mechanisms and detection sensitivity. The review also incorporates illustrative schemes of representative alkaloids and their electrochemical transformations, demonstrating practical applications for pharmaceutical analysis, food safety, and forensic monitoring. By critically assessing the strengths and limitations of current methodologies, this work offers a valuable resource for researchers and professionals in electroanalytical chemistry, pharmaceutical sciences, biomedicine, and toxicology, supporting the development of more selective and efficient voltammetric techniques for alkaloid investigation.