Chemical Detection Methods Research Articles

Simple chemical detection based on a surface-modified electroosmotic pump via interval immobilization.

Environmental water quality monitoring plays an important role in human health risk assessments for pharmaceuticals in water and pollutant source control. A new chemical detection method was developed to enhance molecular selectivity and portability by combining the molecularly imprinted technique and an electroosmotic pump (EOP), which requires only a small pump, batteries and stopwatch in principle. Selective chemical adsorption on the surface-modified EOP decreases the pumping performance of EOP due to a decrease in the surface electric charge. For proof of concept, the microfabricated EOPs with chemical surface treatment were used to investigate the effects of surface chemical change on pumping performance. The microfluidic EOP of a size of 20 mm × 20 mm × 1 mm was modified by an interval immobilization method using the template of 4-(tributylammonium-methyl)-benzyltributylammonium chloride (TBTA) and evaluated by measuring EOF. The pumping performance of the surface-modified EOP was decreased by the selective adsorption of TBTA to a two-point recognition site on the EOP surfaces. The relationships between the flow rate and the TBTA concentration were fitted to the Langmuir equation. The EOP can selectively detect the model substance even in a mixture solution with a different chemical compound. This molecular imprinted EOP does not require large and expensive instruments for driving the device and chemical detection, which can be applied to a portable analytical device for onsite analysis.

Comparison of the degree of microbiological contamination of selected closed rooms using the method of fast detection with a multi-sensor matrix

The problem of microbiological contamination has been an important issue in the construction and environmental industry for many years. The concept of Sick Building Syndrome (SBS) means a combination of different health conditions, which can be eradicated by being in a specific interior. The basic prerequisite for an effective analysis of the issue is a detailed knowledge of its causes and consequences for people. In many cases, the reason for SBS is an increase in humidity of building partitions, but also excessive humidity in closed rooms, which becomes the cause of microbiological contamination of building objects. These factors create appropriate conditions for the development of microorganisms, adversely affecting the durability of the building, its technical condition, and above all the health of residents. This article presents a comparison of two rooms of technical nature, characterised by a different degree of microbiological load. For the analysis, a room with a high degree of microbiological contamination and a room in which high quality internal air quality is maintained were selected. The degree of a microbiological load will be determined on the basis of sensory measurements carried out with the use of microbiological, chemical, and rapid detection method using a multisensor matrix. The multi-sensor matrix forms the basis for electronic nose technology, which can also be used to assess internal air quality.

Practical application of Westgard Sigma rules with run size in analytical biochemistry processes in clinical settings.

BackgroundThe performance of 18 routine chemical detection methods was evaluated by the sigma (σ) metric, and Westgard Sigma rules with run size were used to establish internal quality control (IQC) standards to reduce patient risks.Materials and methodsExternal quality assessment (EQA) and internal quality control data from 18 assays in a biochemical laboratory were collected from January to June 2020. The sigma values of each assay were calculated, based on the bias, total error allowable, and coefficient of variation, appropriate quality control rules were selected. According to the quality goal index, the main causes of poor performance were determined to guide quality improvement.ResultsAt IQC material level 1, seven of the 18 assays achieved five sigma (excellent), and five assays (UA, Crea, AMY, TC and Na) showed world‐class performance. At IQC material level 2, 14 of the 18 assays achieved 5 sigma (excellent), and thirteen assays (UA, ALT, CK, Crea, AMY, K, AST, ALP, Na, LDH, Mg, TC and GGT) showed world‐class performance. The quality goal index (QGI) was calculated for items with analysis performance <5 sigma, and the main causes of poor performance were determined to guide quality improvement.ConclusionsWestgard sigma rules with run size are an effective tool for evaluating the performance of biochemical assays. These rules can be used to more simply and intuitively select the quality control strategy of related items and reduce the risk to patients.

Paralytic shellfish toxins and associated toxin profiles in bivalve mollusc shellfish from Argentina

Paralytic Shellfish Poisoning is a potentially fatal syndrome, resulting from the filter-feeding activities of marine molluscs accumulating harmful neurotoxins naturally occurring in microalgae. Outbreaks are well recognised throughout most regions of the world, but with the highest levels of toxicity to date recorded in mussels from Argentina. Whilst toxicity has been documented for selected outbreaks over the years, testing has been conducted using a mouse bioassay. Consequently there is a need to establish baseline data utilising modern chemical detection methods, which also facilitate the quantification of individual toxin analogues, giving useful data on toxin profiles as well as total sample toxicity. In this study, 151 shellfish samples harvested from the marine waters of Argentina between 1980 and 2012 were subjected to analysis by liquid chromatography with fluorescence detection, since Jan 2019 the European Union reference method for PSP determination. Total PST concentrations were found to vary enormously throughout the coastline of Argentina, with higher levels of toxins found in the central regions of Rio Negro and Chubut. Toxin profiles in terms of molar percentage of total concentrations were dominated by the gonyautoxins GTX1&4 and GTX2&3, followed by C1&2, STX and dcGTX2&3, with minor levels of other analogues previously not reported in the country. Profiles were found to vary significantly, with statistical clusters of profile types associated with a wide range of factors, including species, spatial and temporal differences, as well as likely source microalgae species and potential toxin transformation pathways. Overall application of the chemical detection method has confirmed both the significant risk to shellfish consumers in Argentina with periodic outbreaks of extremely high toxin levels and a large variability in toxin profiles relating in part to previously reported variabilities in microalgal toxin content. The study has demonstrated the potential for the method to systematically study the relationships between toxicity, toxin profile, source phytoplankton and other environmental factors.

Nerve agents: chemical structures, effect mechanisms and detection methods

With the discovery of chemical weapons, mankind has faced a great threat. These weapons are also called weapon of mass destruction and cause mass human deaths in the region where they are used, regardless of whether they are soldiers or civilians. Countries have focused on chemical defense activities because of the easy production and development of chemical weapons and negative psychological effects on the public. Many people were killed or injured due to the use of chemical weapons during World War I. Nerve agents started to be used in making chemical weapons before World War II began. Thus, the threat of chemical weapons on humanity has reached a much more critical point. Especially during World War II and the Cold War, the development of chemical weapons and the production of nerve agents increased more than ever.In this review, various sensor systems developed for detecting nerve agents have been investigated and these sensors have been compared in terms of operating principles and detection limits.

Hybrid Operational Concept with Chemical Detection UAV and Stand-off Chemical Detector for Toxic Chemical Cloud Detection

Early-detection and monitoring of toxic chemical gas cloud with chemical detector is essential for reducing the number of casualties. Conventional method for chemical detection and reconnaissance has the limitation in approaching to chemically contaminated site and prompt understanding for the situation. Stand-off detector can detect and identify the chemical gas at a long distance but it cannot know exact distance and position. Chemical detection UAV is an emerging platform for its high mobility and operation safety. In this study, we have conducted chemical gas cloud detection with the stand-off chemical detector and the chemical detection UAV. DMMP vapor was generated in the area where the cloud can be detected through the field of view(FOV) of stand-off chemical detector. Monitoring the vapor cloud with standoff detector, the chemical detection UAV moved back and forth at the area DMMP vapor being generated to detect the chemical contamination. The hybrid detection system with standoff cloud detection and point detection by chemical sensors with UAV seems to be very efficient as a new concept of chemical detection. Keywords: UAV, Chemical Detection, CWA, Stand-off Detection

Using Histological and Chemical Methods for Detection of Unauthorized Tissues Addition in Emulsion Type Meat Product

Total twenty different processed meat plant producing emulsion type sausage were histologically and chemically examined for detection of adulteration with unauthorized tissues. Results revealed that samples were adulterated with different types of animal tissues included; hyaline cartilage, tendon, spongy bone, peripheral nerve trunk, basophilic matrix, lymphatic tissue, fascia, fibrocartilage and vascular tissue. Moreover, these samples were adulterated Also, adulterated with plant tissue included; plant stem, leaves and root. Chemical analysis showed a significant difference in their chemical composition (moisture, fat, protein, ash and calcium) content. Moisture and fat content varied around the permissible limit of E.S.S. while low protein, high ash and calcium content was detected in the examined samples. Therefore, Histological and chemical examinations can be used as reliable methods to detect adultration using unauthorized addition of both animal and plant tissues in processed meat product samples which revealed a high level of falsification.

The study progress and application of dithionite reduction technology in the treatment of environmental pollutants

Environmental pollution has seriously influenced the human health and ecological security. As a strong reducing agent, dithionite has been gradually drawing the attention of researchers and engineers in the environmental field. Studies had been conducted by employing dithionite to treat the pollutants such as halogenated organic compounds, oxyacid salts, and heavy metals. However, few works were focusing on the dithionite reduction, especially the dithionite detection. This report aimed to review the characteristic of dithionite including the chemical properties and detection methods. The research progressing on the treatment of environmental pollutants by the reactive species generated from dithionite was also summarised. However, ultraviolet seemed to be the only choice of the dithionite activation methods, no matter what pollutant was to be degraded. Accordingly, the research, on the development of dithionite detection and activation methods, was prospected.

Functionalized PProDOT@nitrogen-doped carbon hollow spheres composites for electrochemical sensing of tryptophan

In this study, the functional groups (-OH,-SH) grafted poly (3,4-proplenedioxy thiophene)@nitrogen-doped carbon hollow spheres (N-HCS) composites were prepared by a chemical oxidative polymerization method for the electrochemical detection of tryptophan. The relationship between the structure and electrochemical performance were systematically studied. The improvement of synergetic effect resulted from strong non covalent bonding effect between the functional groups of N-HCS and polymers, as well as the interaction between functional groups (-OH,-SH) of polymers and small biomolecules enhanced the sensitivity and catalytic properties of the composites. The constructed sensors from composites of functionalized polymers@N-HCS modified glassy carbon electrodes displayed higher electrochemical sensing behavior for detection of tryptophan than unfunctionalized polymer@N-HCS. Furthermore, the composites of functional groups (-OH, –SH) grafted poly (3,4-proplenedioxy thiophene)@N-HCS exhibited a wide range (0.2–90 μM and 0.1–100 μM), low detection limit (4.16 nM and 9.2 nM) and good sensitivity (382.16 μAmM−1cm−2 and 433.12 μAmM−1cm−2), suggesting that the functional groups (-OH,-SH) grafted poly (3,4-proplenedioxythiophene)@N-HCS could be a promising and convenient material for the electrochemical sensing of tryptophan.

Chemical probes and methods for single-cell detection and quantification of epichaperomes in hematologic malignancies.

Detection of protein connectivity dysfunctions in biological samples, i.e., informing on how protein-protein interactions change from a normal to a disease state, is important for both biomedical research and clinical development. The epichaperome is an executor of protein connectivity dysfunction in disease, and thus a surrogate for its detection. This chapter will detail on published methods for epichaperome detection and quantification that combine the advantages of multiparameter flow cytometry with those of the PU-FITC fluorescently labeled epichaperome detection probe. It will offer a comprehensive method description that includes the synthesis and characterization of an epichaperome detection probe and of the negative control probe, the preparation of the biospecimen for epichaperome analysis, the execution of the epichaperome detection and quantification assay and lastly, the data acquisition and analysis. The method provides, at single-cell level, the functional signature of cells, differentiating itself from other single-cell methods that provide a catalog of molecules.

Sigma Metrics used to Evaluate the Performance of Internal Quality Control in a Clinical Biochemistry Laboratory.

The performance of 17 routine chemical detection methods was evaluated by the Sigma (σ) index, and separate quality control standards were established according to the sigma values of different detection methods. The internal quality control (IQC) and external quality assessment (EQA) data of 17 assays in the biochemical laboratory of our hospital were collected from January to June 2019. Referring to the total allowed error (TEa) standards established in the Health Industry Standards of the People's Republic of China (WS/T 403-2012), the sigma metric of each assay was calculated, the performance level for inspection was evaluated, the quality goal index (QGI) was calculated for items with analysis performance < 5 sigma, and the main causes of poor performance were determined to guide quality improvement. For level 1 internal quality control (IQC), five assays (AMY, Crea, UA, TP, and Na) showed a performance of ≥ 6 sigma levels. Five assays (GGT, LDH, ALP, K, and Ca) had a performance lower than 3 sigma. For level 2 IQC, nine assays (ALT, AST, CK, AMY, Crea, UA, TP, Na, and Mg) achieved 6 sigma, and four assays (GGT, LDH, ALP, and K) achieved less than 3 sigma. Among the 12 assays with a sigma value < 5, the precision of 1 assay should be improved first, the accuracy of 6 assays should be improved next, and both the precision and the accuracy of 5 assays should be improved. The sigma metric is the best tool for evaluating the performance of different test methods. Assays with high sigma values can be evaluated with single-rule quality control, while assays with low values should be evaluated with strict quality control rules.

Electron Microscopic Detection of Single Membrane Proteins by a Specific Chemical Labeling.

SummaryElectron microscopy (EM) is a technology that enables visualization of single proteins at a nanometer resolution. However, current protein analysis by EM mainly relies on immunolabeling with gold-particle-conjugated antibodies, which is compromised by large size of antibody, precluding precise detection of protein location in biological samples. Here, we develop a specific chemical labeling method for EM detection of proteins at single-molecular level. Rational design of α-helical peptide tag and probe structure provided a complementary reaction pair that enabled specific cysteine conjugation of the tag. The developed chemical labeling with gold-nanoparticle-conjugated probe showed significantly higher labeling efficiency and detectability of high-density clusters of tag-fused G protein-coupled receptors in freeze-fracture replicas compared with immunogold labeling. Furthermore, in ultrathin sections, the spatial resolution of the chemical labeling was significantly higher than that of antibody-mediated labeling. These results demonstrate substantial advantages of the chemical labeling approach for single protein visualization by EM.

Construction of Cu doped ZnO nanorods by chemical method for Low temperature detection of NO2 gas

In this report, we have prepared Cu-doped ZnO nanorods by a simplistic wet chemical method with subsequent annealing. The phase formation, optical, surface morphological studies along with the electrical properties of the Cu doped ZnO thin films were characterized by X-ray diffraction (XRD), photoluminescence (PL), field emission scanning electron microscopy (FESEM) and Hall measurements, respectively. The addition of copper (Cu) in to the matrix of ZnO influenced the surface morphology of the product dramatically. The regular hexagonal nanorods-like surface morphology of ZnO becomes a broken rod-like morphology, after addition of copper. Owing to the complexes surface morphology of Cu doped ZnO, the system was used to detect the toxic gases like NO2. The effect of doping on the gas-sensing properties of ZnO was slightly counterintuitive in that they initially increased up to Cu concentrations of 1% before beginning to decline. Meanwhile, the Cu doped ZnO exhibited the gas response of ˜ 71 for 1 ppm of NO2 gas at low operating temperatures. This higher gas sensing response is due to the defect states observed in Cu doped ZnO films. In addition to above mentioned findings, the transformation of n-type ZnO to p-type Cu doped ZnO was also observed. The p-type conductivity is attributed to the holes created in the merging of Cu on Zn sites.

An automated flow-batch analyzer based on spectrophotometry for the determination of nitrite

An automated flow-batch analyzer (FBA) based on spectrophotometry was developed for the determination of nitrite (NO2−) in environmental waters. The FBA consists of a homemade flow cell, light source, detector and a mini-syringe pump, which was controlled by self-designed software written in LabVIEW. Two LEDs and a light-to-voltage converter were used as the light source and detector respectively. The chemical detection method was based on spectrophotometry and modified Griess reaction. With the optimized conditions, the limit of detection (LOD) was 0.018 µmol·L−1 and the relative standard deviations (RSDs) at different concentrations (0–12 µmol·L−1) were 0.54%–3.63% (n=3). Measurements of different aqueous samples (n=21) showed no significant difference between results obtained by developed FBA and a commercial spectrophotometer.

Convergent Evolution of Mucosal Immune Responses at the Buccal Cavity of Teleost Fish.

SummaryThe buccal mucosa (BM) is a critical first line of defense in terrestrial animals. To gain further insights into the evolutionary origins and primordial roles of BM in teleosts here we show that rainbow trout, a teleost fish, contains a diffuse mucosal associated lymphoid tissue (MALT) within its buccal cavity. Upon parasite infection, a fish immunoglobulin specialized in mucosal immunity (sIgT) was induced to a high degree, and parasite-specific sIgT responses were mainly detected in the buccal mucus. Moreover, we show that the trout buccal microbiota is prevalently coated with sIgT. Overall our findings revealed that the MALT is present in the BM of a non-tetrapod species. As fish IgT and mucus-producing cells are evolutionarily unrelated to mammalian IgA and salivary glands, respectively, our findings indicate that mucosal immune responses in the BM of teleost fish and tetrapods evolved through a process of convergent evolution.

Photoelectrochemical Biosensing

Photoelectrochemical sensing represents a unique means for chemical and biological detection, with foci of optimizing semiconductor composition and electronic structures, surface functionalization layers, and chemical detection methods. Here, we have briefly discussed our recent developments of nanowire‐based photoelectrochemical sensing, with particular emphasis on three main detection mechanisms and corresponding examples. We have also demonstrated the use of the photoelectrochemical sensing of real‐time molecular reaction kinetic measurements, as well as direct interfacing of living cells and probing of cellular functions. Figure 1

Preparation of silver nanoparticles coated ZnO/Fe3O4 composites using chemical reduction method for sensitive detection of uric acid via surface-enhanced Raman spectroscopy

In this study, silver nanostructures decorated magnetic nanoparticles for surface-enhanced Raman scattering (SERS) measurements were prepared via heat induced catalytic activity of ZnO nanostructures. The ZnO/Fe3O4 composite was first prepared by dispersing pre-formed magnetic nanoparticles into alkaline zinc nitrate solutions. After annealing of the precipitates, the formed ZnO/Fe3O4 composites were successfully decorated with silver nanostructures by dispersing the composites into silver nitrate/ethylene glycol solution at 95 °C in water bath. To find the optimal condition when preparing Ag/ZnO/Fe3O4 composites for SERS measurements, factors such as reaction time and concentration of silver nitrate were studied. Results indicated that the formation of silver nanoparticles (AgNPs) on ZnO/Fe3O4 was significantly improved with the assistance of ZnO. The concentration of silver nitrate and reaction time affected the morphologies and sizes of the formed composites and optimal condition in preparation of the composites for SERS measurement was found using 100 mM of silver nitrate with a reaction time of 20 min. Under optimized conditions, the obtained SERS intensities were highly reproducible. The substrates were applied for quantitative analysis of uric acid in aqueous solution and a linear response for concentrations up to 10 μM was obtained. Successful application of these prepared composites to determine uric acid in urine sample without any pretreatment of the urine sample was done.

A three-dimensional ratiometric sensing strategy on unimolecular fluorescence\u2013thermally activated delayed fluorescence dual emission

Visualized sensing through fluorescence signals is a powerful method for chemical and physical detection. However, the utilization of fluorescent molecular probes still suffers from lack of precise signal self-calibration in practical use. Here we show that fluorescence and thermally activated delayed fluorescence can be simultaneously produced at the single-molecular level. The thermally activated delayed fluorescence serves as a sensing signal with its wavelength and lifetime both altered correlating to polarity, whereas the fluorescence always remains unchanged as an internal reference. Upon the establishment of a three-dimensional working curve upon the ratiometric wavelength and photoluminescence lifetime vs. polarity, disturbance factors during a relevant sensing process can be largely minimized by such a multiple self-calibration. This strategy was further applied into a precise detection of the microenvironmental polarity variation in complex phospholipid systems, towards providing new insights for convenient and accurate diagnosis of membrane lesions.

A new catalyst Ti doped CdO thin film for non-enzymatic hydrogen peroxide sensor application

A new material, Ti doped CdO (Ti: CdO) semiconductor, is firstly reported by this work for electrochemical non-enzymatic hydrogen peroxide (H2O2) sensor applications which was deposited by a simple, versatile and cost-effective chemical spray pyrolysis method on indium doped tin oxide (ITO) substrate. In the basic studies, first, the withstanding of cubic crystal phase along with worthy crystalline nature is discerned on CdO film after Ti doping, here only the preferentially orientated (200) diffraction plane shifted to (111). Subsequently, the irregular spherically shaped CdO nanoparticles (NPs) morphology changed as nearly uniform size with Ti doping is noticed under thermal pyrolytic decomposition process. The existence of Ti atoms in Ti: CdO film is authentically identified and confirmed using EDX and XPS studies respectively. The absorption and emission properties of CdO and Ti: CdO films are studied and confirmed their narrow band gap nature. Importantly, the Ti: CdO film shows pronounced electrocatalytic activity for the reduction of hydrogen peroxide (H2O2) than pure CdO. Hence, the non-enzymatic electrochemical sensing of Ti: CdO electrode shows a lower detection limit, broad linear range, rapid response time and high sensitivity toward H2O2 detection. This result will boost exploring a new opportunity for the deposition of other metal oxides and semiconductors by using a simple chemical spray pyrolysis method for detection of non-enzymatic H2O2 sensor applications.

Seawater chemical oxygen demand optical detection method based on Raman spectroscopy

Seawater chemical oxygen demand optical detection method based on Raman spectroscopy