Applications In Analytical Chemistry Research Articles

Deep eutectic solvent as stationary phase for flow analysis: Automated trace metal determination in food products

BackgroundDeep eutectic solvents (DES) have emerged as effective solvents that address many challenges in analytical chemistry, particularly in microextraction. However, until now, their use has been primarily focused on extraction processes. This has significantly limited their application in analytical chemistry, especially in flow analysis, where the high viscosity of DES has made their use difficult. ResultsThis paper presents a novel DES-based liquid-liquid microextraction approach for the separation and determination of trace metals in foods using an automated flow analysis system. In this study, a DES composed of thymol and thionalide was first prepared and thoroughly characterized by spectroscopic (IR, NMR) and differential scanning calorimetry techniques. The COSMO-SAC model was employed to predict the solubility of metal salts (Cu, Cd, Pb, and Hg) in the new DES. The solvent was applied to glass fiber as a stationary phase in an extraction column in a flow analysis. After microwave digestion of food samples, metals were extracted by this DES in an automated mode and subsequently eluted with an aqueous thiourea solution. The procedure demonstrated limits of detection (LOD) of 6 μg kg−1 for mercury, 4 μg kg−1 for copper, 6 μg kg−1 for lead and 0.6 μg kg−1 for cadmium. SignificanceThis study represents the first application of a DES-based stationary phase in automated flow analysis, significantly enhancing extraction efficiency. The procedure enables precise and reliable determination of trace metals in food products, aligning with green chemistry principles by minimizing waste.

Effective Identification and Highly Sensitive Quantification of Fructo-oligosaccharide Isomers with Bi2Se3 Nanosheet-Assisted Laser Desorption Ionization Mass Spectrometry.

The growing interest in fructo-oligosaccharides (FOSs) necessitates the effective monitoring of product quality. Identifying and quantifying FOS isomers from the same sources are challenging. Here, we report a new method using Bi2Se3 nanosheets as the matrix for matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS), achieving effective differentiation of oligosaccharide isomers through MALDI-MS/MS. Notably, four isomers of pentasaccharides and two isomers of heptasaccharides were successfully identified, with a remarkably low limit of detection of 0.06 pmol. Our approach enabled the specific quantification of 1F-fructofuranosylnystose in commercial FOS products, positioning it as a promising tool for oligosaccharide isomer quantification in nutritional food products. Furthermore, this technique facilitates the rapid and sensitive detection of various saccharides and a wide range of other small molecules with enhanced signal intensities and improved reproducibility. Overall, it facilitates the rapid, selective, and sensitive detection of various saccharides and other small molecules, enhancing analytical chemistry and food science applications.

Introduction and Development of Surface-Enhanced Raman Scattering (SERS) Substrates: A Review.

Since its discovery, the phenomenon of Surface Enhanced Raman Scattering (SERS) has gradually become an important tool for analyzing the composition and structure of substances. As a trace technique that can efficiently and nondestructively detect single molecules, the application of SERS has expanded from environmental and materials science to biomedical fields. In the past decade or so, the explosive development of nanotechnology and nanomaterials has further boosted the research of SERS technology, as nanomaterial-based SERS substrates have shown good signal enhancement properties. So far, it is widely recognized that the morphology, size, composition, and stacking mode of nanomaterials have a very great influence on the strength of the substrate SERS effect. Herein, an overview of methods for the preparation of surface-enhanced Raman scattering (SERS) substrates is provided. Specifically, this review describes a variety of common SERS substrate preparation methods and explores the potential and promise of these methods for applications in chemical analysis and biomedical fields. By detailing the influence of different nanomaterials (e.g., metallic nanoparticles, nanowires, and nanostars) and their structural features on the SERS effect, this article aims to provide a comprehensive understanding of SERS substrate preparation techniques.

Triboelectric Programmed Droplet Manipulation for Plug‐and‐Play Assembly

AbstractProgrammed droplet transport which is typically directed by surface energy gradients or external fields, is crucial in domains ranging from chemical reaction modulation to self‐powered intelligent sensing. However, droplet motion control remains constrained by path reconfiguration, requirements on chemical surface modification, and platform complexity. Here, a more universal plug‐and‐play droplet manipulation paradigm based on liquid‐solid contact electrification and triboelectricwetting on common dielectric surfaces is reported. By regulating the electrical double layer via asymmetric ion dynamics, the triboelectric charge polarity of droplets can be adjusted, enabling in situ manipulation without path reconfiguration dictated by the conventional droplet motion output. Droplets achieved an ultrahigh velocity of 450 mm s−1 on general surfaces, significantly exceeding the speeds observed in droplets subjected to constant electrostatic fields with chemical modifications. This flexible and modular functionally decoupled manipulation strategy offers an environmentally friendly, cost‐effective, and versatile paradigm, facilitating applications in chemical analysis and smart sensing.

Doping of Mn2+ ion into boron quantum dots with enhanced fluorescence properties for sensing of L-thyroxine biomarker and bioimaging applications

L-thyroxine serves as a primary biomarker for diagnosing hypothyroidism and it is also utilized in hormone replacement therapy. Regular assessment of thyroxine levels is crucial for preventing health issues in hypothyroid patients, suggesting the requirement of a facile analytical tool for the detection of L-thyroxine. In this work, a straightforward and efficient synthetic method is introduced for in-situ preparation of Mn2+-doped boron quantum dots (Mn2+@B-QDs) derived from boron powder through a solvothermal reaction. The introduction of Mn2+ ion into B-QDs not only enhances fluorescence efficiency but also provides favorable sites within the QDs, expanding their potential applications in analytical chemistry. The blue fluorescent Mn2+ @B-QDs exhibited excellent performance for the selective recognition of L-thyroxine via a dynamic quenching mechanism. Under ideal conditions, a good linear relation was observed between the fluorescence emission intensity ratio of Mn2+@B-QDs and the concentration of L-thyroxine in the range of 0.125–5 μM, with a lower detection limit of 59.86 nM. The Mn2+@B-QDs exhibited the negligible cytotoxicity against A549 lung cancer cell lines and demonstrated good biocompatibility toward Saccharomyces cerevisiae cells.

A novel and facile oxygen-activated time-temperature indicator with wide temperature monitoring range and good stability based on the laccase-like nanozyme

BackgroundTime-Temperature Indicator (TTI) is an indicator device for real-time monitoring of the thermal history of the product. Due to the enzymatic reactions are affected by both time and temperature, enzymatic TTIs have been extensively studied and developed in recent years. However, enzymatic TTIs contain biologically active molecules (enzymes), which require high storage and use conditions. Most of them are designed to mix the system species together and irreversible reaction is undertaken. Nanozymes are the synthetic nanomaterials with similar biocatalytic functions as natural enzymes, which have extensive applications in analytical chemistry, biosensing, and environmental protection due to their facile synthesis, low cost, high stability and durability. ResultsThis work proposed to replace the natural laccase to laccase-like nanozyme, designed a novel and facile O2-activated time-temperature indicator for the first time. Nanozyme had excellent thermal and storage stability, which could maintain fabulous catalytic activity in the wide temperature range of 10–80 °C and after a long-term storage. Based on the O2 was required to participate in the oxidation of laccase-catalyzed substrates, a squeeze-type O2-activated TTI was designed by controlling O2 in the TTI system. The TTI was activated through extruding the O2-coated airbag ruptured and producing an irreversible color reaction. Combined with a smartphone to extract the chromaticity for portable visual real-time monitoring. Five sets of TTIs were prepared based on the concentration of nanozyme, and the activation energies (Ea) ranging from 28.45 to 72.85 kJ mol−1, which were able to be fitted to products with Ea ranging from 3.45 to 97.8 kJ mol−1 and the monitoring-time of less than 7 days. SignificanceCompared to the traditional enzymatic TTI, the TTIs designed based on nanozyme has the advantages of controlled activation, wider temperature monitor range and good stability. Providing a new approach to the development of real-time monitoring of smart devices.

Chemoexcited Formation and Radiationless Decay Dynamics of Firefly Chromophore.

Multistate nonadiabatic dynamics combined with Mixed-Reference Spin-Flip Time-Dependent Density Functional Theory (MRSF-TDDFT) were performed to investigate the chemoexcitation dynamics of firefly dioxetanone (FDO- in S0) to oxyluciferin (OxyLH- in S1) and its subsequent decay dynamics. The formation of oxyluciferin occurs within approximately 100 fs and is primarily controlled by oscillatory CO2 decarboxylation. Unexpected radiationless decay from oxyluciferin was also observed, facilitated by intramolecular rotation. Simulations under three thermal conditions reveal that higher initial thermal energy not only enhances the formation of oxyluciferin but also increases radiationless decay by surpassing barriers to the ground state. Conversely, lower thermal energy conditions reduce oxyluciferin formation but suppress radiationless decay. These findings suggest that optimal conditions for higher chemiluminescence quantum yield involve initial high thermal energy to accelerate CO2 decarboxylation and gradual thermal dissipation to prevent intramolecular rotation of oxyluciferin. This approach could enhance the chemiluminescence quantum yield beyond the current limit of 40%, offering significant potential for applications in biological imaging and analytical chemistry.

A comprehensive investigation of cholesteric liquid crystal interpenetrating polymer networks for metal ion sensor technology

This study outlines the fabrication process of a photonic polymer cholesteric liquid crystal (PCLC) engineered for dynamic response to external stimuli. The methodological framework includes the precise templating of PCLC onto an interpenetrating polymer network (IPN) following selective UV crosslinking and the careful removal of nonreactive mesogens. The sensor component of the PCLC film is composed of poly(acrylic acid) hydrogel. A key aspect of the process involves the formation of micro-holes through acetone treatment to enhance sensitivity. Additionally, functionalization with potassium hydroxide (KOH) improves the detection of calcium ions (Ca2+) by disrupting hydrogen bonds and facilitating the formation of potassium carboxylate salt. Combining the inherent properties of PCLC with the hydrogel’s responsiveness to metal ions results in a sophisticated sensor designed to detect Ca2+ ions through the modulation of PCLC pitch, creating distinct transmission bands. The manuscript provides a detailed quantitative analysis of stimulus-induced changes in PCLC wavelength, using measured spectra to refine and optimize process conditions. The resulting PCLC sensor demonstrates exceptional sensitivity (9.30 nm/mM) within the 1–15 mM Ca2+ ion concentration range, along with excellent specificity. This cost-effective, user-friendly, and colorimetric sensing modality holds significant promise for various applications in analytical chemistry.

Optical Fiber Bragg Grating as a Strain Sensor

Abstract: The sensor technology industry has come to recognize and value the optical fibre sensor (OFS). It is frequently used to detect changes in the environment and to respond to outputs from other systems, such as those in industrial, monitoring, and chemical analysis applications. While a brief segment of optical fiber with a particular wavelength is reflected with light in a device known as a Fibre Bragg Grating, a Bragg reflector begins to grow and transmit all other wavelengths. Through software modeling, the current study focuses on the changing traits and behaviors of temperature and strain sensors that are used with fiber bragg gratings (FBG). The main objective of this work is to study the properties and behavior of strain sensors utilized in conjunction with fiber bragg gratings. A strain sensor can be used to determine the strain in an object whose resistance changes when force is applied

Optical Fiber Bragg Grating As A Temperature Sensor

The optical fibre sensor (OFS) has become quite well-known and prominent in the sensor technology industry. It is often used to react to outputs from other systems, like those in industrial, monitoring, and chemical analysis applications, and to detect changes in the environment. A Fibre Bragg Grating (FBG) is a device that allows light to be reflected from a short section of optical fiber at a specific wavelength, while the Bragg reflector expands and transmits all other wavelengths. The current effort focuses on the evolving characteristics and behaviors of strain and temperature sensors operating on fiber bragg gratings through computer modeling. The temperature sensor is employed to detect and quantify any variations in temperature on the Fiber Bragg Grating that could result in accidents or fires. This will show how the Fibre Bragg Grating may be used to showcase temperature sensors.

Harnessing Cooperative Multivalency in Thioguanine for Surface-Enhanced Raman Scattering (SERS)-Based Differentiation of Polyfunctional Analytes Differing by a Single Functional Group.

Small-molecule receptors are increasingly employed to probe various functional groups for (bio)chemical analysis. However, differentiation of polyfunctional analogs sharing multiple functional groups remains challenging for conventional mono- and bidentate receptors because their insufficient number of binding sites limits interactions with the least reactive yet property-determining functional group. Herein, we introduce 6-thioguanine (TG) as a supramolecular receptor for unique tridentate receptor-analyte complexation, achieving ≥97 % identification accuracy among 16 polyfunctional analogs across three classes: glycerol derivatives, disubstituted propane, and vicinal diols. Crucially, we demonstrate distinct spectral changes induced by the tridentate interaction between TG's three anchoring points and all the analyte's functional groups, even the least reactive ones. Notably, hydrogen bond (H-bond) networks formed in the TG-analyte complexes demonstrate additive effects in binding strength originating from good bond linearity, cooperativity, and resonance, thus strengthening complexation events and amplifying the differences in spectral changes induced among analytes. It also enhances spectral consistency by selectively forming a sole configuration that is stronger than the respective analyte-analyte interaction. Finally, we achieve 95.4 % accuracy for multiplex identification of a mixture consisting of multiple polyfunctional analogs. We envisage that extension to other multidentate non-covalent interactions enables the development of interference-free small molecule-based sensors for various (bio)chemical analysis applications.

Tungsten oxide‐iodide/poly‐2‐aminobenzenethiol nanocomposite with iodine intercalation as a promising electrode for potentiometric sensing of Pb2+ ions in water

AbstractTungsten oxide‐iodide/poly‐2‐aminobenzenethiol nanocomposite (WO2I2/P2ABT) is created through the introduction of iodine into polymer chains, where iodine serves as an oxidizing agent during the synthesis process. With a highly porous structure, the sensing capabilities of WO2I2/P2ABT for detecting Pb2+ ions are successfully demonstrated, revealing a Nernstian slope of 26.2 mV/decade. This detection is accomplished through a simple potentiometric technique, employing a simple two‐electrode cell setup. To further validate its performance, cyclic voltammetry is conducted using a three‐electrode system, revealing a remarkable sensitivity of 7.2 × 10−5 A M−1 for Pb2+ ions. The nanocomposite sensor's selectivity is rigorously examined by subjecting it to testing in the presence of 0.01 M interfering ions. The results unequivocally demonstrate that the sensor remains unresponsive to these interfering ions, underscoring its remarkable selectivity for Pb2+ ions. Moreover, the sensor's behavior is evaluated under real‐world conditions using natural samples, where, no indications of interference from other ions are observed. This is estimated by the absence of cyclic peaks in the voltammogram, indicating the sensor's unique ability to selectively detect Pb2+ ions without being perturbed by other ions that may be naturally occurring in the samples. These findings emphasize the nanocomposite sensor's potential for a wide array of applications in environmental monitoring and analytical chemistry. Its extraordinary combination of high sensitivity, impeccable selectivity, and robust performance in practical scenarios establishes it as an invaluable tool for detecting Pb2+ ions across various contexts.

Symmetrical dual-D and dual-core single-mode fiber surface plasmon resonance liquid sensor

A symmetrical dual-D and dual-core single-mode fiber surface plasmon resonance (SPR) liquid sensor is designed for biological detection. The dual-core design optimizes the transmission path, improves the momentum matching between free electrons and photons, and facilitates bidirectional coupling, consequently amplifying the SPR effect and enabling sensitive monitoring of the refractive index changes of biological solutions. In this structure, a gold wire is placed in the middle of the polished surface of the double-D-shaped single-mode fiber (SMF) to produce high-quality free electrons and promote the mode-coupling excitation of the SPR effect. The characteristics of the sensor are analyzed by the finite element method, and the important structural parameters are optimized systematically. The sensor can be operated in the near-infrared region for a refractive index (RI) range of 1.31–1.40 with a maximum wavelength sensitivity (WS) of 21,000 nm/RIU, amplitude sensitivity of 586.62RIU−1, as well as resolution of 4.76×10−6RIU. Small changes in the refractive index can be detected by the sensor and it can be produced easily by conventional manufacturing techniques. The sensor thus has wide application prospects in biomedical and chemical analysis and related applications.

A Subject Review on Application of Analytical Chemistry in the Mitochondrial Medicine

Understanding energy metabolism and intracellular energy transmission requires knowledge of the function and structure of the mitochondria. Issues with mitochondrial morphology, structure, and function are the most prevalent symptoms. They can damage organs such as the heart, brain, and muscle due to a variety of factors, such as oxidative damage, incorrect metabolism of energy, or genetic conditions. The control of cell metabolism and physiology depends on functional connections between mitochondrial and biological surroundings. Therefore, it is essential to research mitochondria in situ or in vivo without isolating them from their surrounding biological environment. Finding and spotting abnormal alterations in mitochondria is the primary research technique for understanding mitochondrial illnesses. The purpose of this review is to collect original studies and papers describing a variety of analytical chemistry tasks carried out in mitochondria. Analytical chemistry is essential to the biological and medical sciences. Several analytical methods have been used in this field, such as chromatographic, spectroscopic, spectrophotometric, electrochemical analysis, and electrospray ionization mass spectrometry. While spectroscopic techniques in particular have yielded important information in certain cases, the nature of these techniques nevertheless limits the information that can be collected. Mass spectrometry may, however, produce incredibly detailed datasets.

Harnessing Cooperative Multivalency in Thioguanine for SERS Differentiation of Polyfunctional Analytes Differing by Single Functional Group

Small‐molecule receptors are increasingly employed to probe various functional groups for (bio)chemical analysis. However, differentiation of polyfunctional analogs sharing multiple functional groups remains challenging for conventional mono‐ and bidentate receptors because their insufficient number of binding sites limits interactions with the least reactive yet property‐determining functional group. Herein, we introduce 6‐thioguanine (TG) as a supramolecular receptor for unique tridentate receptor‐analyte complexation,achieving ≥ 95% identification accuracy among 16 polyfunctional analogs across three scenarios: glycerol derivatives, disubstituted propanes, and vicinal diols. Crucially, we demonstrate distinct spectral changes induced by the tridentate interaction between TG’s three anchoring points and all the analyte’s functional groups, even the least reactive ones. Notably, H‐bond networks formed in the TG‐analyte complexes demonstrate additive effect in binding strength originating from good bond linearity, cooperativity, and resonance, thus strengthens complexation events and amplifies the differences in spectral changes induced among analytes. It also enhances spectral consistency by selectively form a sole configuration that is stronger than the respective analyte‐analyte interaction. Finally, we achieve 95.4% accuracy for multiplex identification of a mixture consisting of multiple polyfunctional analogs. We envisage that extension to other multidentate non‐covalent interactions enables the development of interference‐free small molecule‐based sensors for various (bio)chemical analysis applications.

Revolutionizing food science with mass spectrometry imaging: A comprehensive review of applications and challenges.

Food science encounters increasing complexity and challenges, necessitating more efficient, accurate, and sensitive analytical techniques. Mass spectrometry imaging (MSI) emerges as a revolutionary tool, offering more molecular-level insights. This review delves into MSI's applications and challenges in food science. It introduces MSI principles and instruments such as matrix-assisted laser desorption/ionization, desorption electrospray ionization, secondary ion mass spectrometry, and laser ablation inductively coupled plasma mass spectrometry, highlighting their application in chemical composition analysis, variety identification, authenticity assessment, endogenous substance, exogenous contaminant and residue analysis, quality control, and process monitoring in food processing and food storage. Despite its potential, MSI faces hurdles such as the complexity and cost of instrumentation, complexity in sample preparation, limited analytical capabilities, and lack of standardization of MSI for food samples. While MSI has a wide range of applications in food analysis and can provide more comprehensive and accurate analytical results, challenges persist, demanding further research and solutions. The future development directions include miniaturization of imaging devices, high-resolution and high-speed MSI, multiomics and multimodal data fusion, as well as the application of data analysis and artificial intelligence. These findings and conclusions provide valuable references and insights for the field of food science and offer theoretical and methodological support for further research and practice in food science.

Recent Advances in Fluorescent Biosensor: A Comprehensive Review

Herein, short review paper investigated the rapidly progress in fluorescent biosensors field and their significant influences on analytical chemistry applications. An electrical signal can be produced from a biological reaction using an integrated receptor-transducer device called a biosensor. Because there are so many uses for biosensors in the medical field, including medication delivery, environmental monitoring, water and food quality monitoring, and illness detection, biosensor design and development have become a top priority for scientists and researchers in the last ten years. In the beginning, we started to explain the basic principles of fluorescence. Then, we moved to discuss about the current advancements, creative sensor designs, and the fusion of materials science and nanotechnology. The paper highlighted the sensitivity of fluorescent biosensors by addressing a wide range of applications, including biological research, environmental monitoring, and medical diagnostics. This review paper censoriously assessed the present difficulties, such as interference and constrained dynamic range, and provided explanations into ongoing research. Advanced material and nanotechnology integration is emerging as a force that improves biosensor performance and broadens their uses. This study also discussed the future possible breakthroughs in biosensor technology and its broad use in a variety of scientific and societal fields.

Unravelling the potential of magnetic nanoparticles: a comprehensive review of design and applications in analytical chemistry.

The study of nanoparticles has emerged as a prominent research field, offering a wide range of applications across various disciplines. With their unique physical and chemical properties within the size range of 1-100 nm, nanoparticles have garnered significant attention. Among them, magnetic nanoparticles (MNPs) exemplify promising super-magnetic characteristics, especially in the 10-20 nm size range, making them ideal for swift responses to applied magnetic fields. In this comprehensive review, we focus on MNPs suitable for analytical purposes. We investigate and classify them based on their analytical applications, synthesis routes, and overall utility, providing a detailed literature summary. By exploring a diverse range of MNPs, this review offers valuable insights into their potential application in various analytical scenarios.

Frequency-Domain Low-Wavenumber Hyperspectral Stimulated Raman Scattering Microscopy.

In recent years, stimulated Raman scattering (SRS) microscopy has experienced rapid technological advancements and has found widespread applications in chemical analysis. Hyperspectral SRS (hSRS) microscopy further enhances the chemical selectivity in imaging by providing a Raman spectrum for each pixel. Time-domain hSRS techniques often require interferometry and ultrashort femtosecond laser pulses. They are especially suited to measuring low-wavenumber Raman transitions but are susceptible to scattering-induced distortions. Frequency-domain hSRS microscopy, on the other hand, offers a simpler optical configuration and demonstrates high tolerance to sample scattering but typically operates within the spectral range of 400-4000 cm-1. Conventional frequency-domain hSRS microscopy is widely employed in biological applications but falls short in detecting chemical bonds with a weaker vibrational energy. In this work, we extend the spectral coverage of picosecond spectral-focusing hSRS microscopy to below 100 cm-1. This frequency-domain low-wavenumber hSRS approach can measure the weaker vibrational energy from the sample and has a strong tolerance to sample scattering. By expanding spectral coverage to 100-4000 cm-1, this development enhances the capability of spectral-domain SRS microscopy for chemical imaging.

Cost-Effective Fabrication of Polydimethylsiloxane (PDMS) Microfluidics for Point-of-Care Application

Microfluidics fabrication pertains to the construction of small-scale devices and systems that manipulate and control small volumes of fluids. This process involves precise engineering and manufacturing procedures aimed at designing and producing these devices, which find applications in healthcare, environmental monitoring, and chemical analysis. The present study showcases an inexpensive approach to fabricate microfluidics channels using PDMS biopolymer and soft lithography technique to achieve laminar fluid flow. Initially, a robust and adhesive mold was created by fabricating a master template using several layers of SU-8 5 and SU-8 2015 negative photoresists. Subsequently, PDMS microfluidics channels were replicated and sealed onto a glass substrate through plasma bonding treatment. High-power microscopy images and profilometer analyses demonstrated successful fabrication with minimal deviation from the initial designs and the fabricated devices (less than 0.07 mm, less than 0.6°). Both the SU-8 master template and PDMS replicate displayed average microchannel height values and surface roughness of 100 μm and 0.26 μm or lower, respectively. Additionally, the fluid test confirmed laminar flow without any leakage post plasma oxidation, indicating the completion of an efficient and cost-effective fabrication process.