Analytical Methods : Advancing Methods and Applications

Dithiocarbamate fungicides (DTCs) have been widely used all over the world. Some of them show toxicities, such as growth toxicity and teratogenicity. Therefore, the analysis of DTCs in environments or crops is very significant. However, their direct and individual analysis was difficult, because most of them are metal complex compounds and have macromolecular properties and a low solubility in water or organic solvents. In the conventional analytical methods for DTCs, the total amount of DTCs was obtained by the quantification of the derivatives of the ligand or by measuring the carbon disulfide formed by the decomposition of the fungicides...

An elevated level of homocysteine (Hcy) in serum is closely related to the development of various diseases. Therefore, homocysteine has been widely employed as a biomarker in medical diagnosis and the on-site detection of homocysteine is highly desired. In this study, a truncated highly specific aptamer for homocysteine was screened and used to design a lateral flow strip (LFS) for the detection of homocysteine. The aptamer was derived from a previously reported sequence. Based on the result of molecular docking, the original sequence was subjected to truncation, resulting in a reduction of the length from 66 nt to 55 nt...

The detection of liquid electrical conductivity has board applications in food safety testing, water quality monitoring, and agricultural soil analysis. Electrodes used in traditional liquid electrical conductivity detection come into direct contact with liquid, leading to electrode contamination and affecting the accuracy of the detection results. The capacitively coupled contactless conductivity detection (C4 D) method effectively addresses this issue. However, impurity particles present in the solution can compromise the consistency and repeatability of detection results...

The development of paper-based devices has drawn a significant amount of attention, ranging from the creation of paper electronics to microfluidic devices. The flow of fluids through the paper substrate can be controlled by establishing a variety of barriers, which can be accomplished by either cutting or producing layers that are hydrophobic. Through the utilisation of this feature, a number of investigations, including mixing, modifying, and analytical studies, have been carried out on the paper substrate...

Facile electro-activated glassy carbon electrodes (e-GCEs), which are prepared in electrolyte solution with a certain potential for a few seconds, have been verified to improve analytical performance toward not a few electro-active molecules recently. Nevertheless, how and why the potential plays an important role is not clear, and has even not received enough consideration. In this paper, we found that the mode and the range of applied potential significantly impacted the sensitivity of methyl parathion (MP), which is a typical pesticide with the electro-active group of -NO2 ...

Sweet tea is a functional herbal tea with anti-inflammatory, anti-diabetic, and other effects, in which phloridzin and trilobatin are two functional compounds. However, the current methods for their quantification are time-consuming, costly, and environmentally unfriendly. In this paper, we propose a rapid method that integrates online pressurized liquid extraction and high-performance liquid chromatography featuring a superficially porous column for fast separation. Moreover, we employ an equal absorption wavelength method to eliminate using multiple standard solutions and relative calibration factors...

Solid phase extraction (SPE) and liquid chromatographic (LC) separation of nucleobases and nucleosides are challenging due to the high hydrophilicity of these compounds. Herein we report a novel on-line SPE-LC-MS/MS method for their quantification after pre-column derivatization with chloroacetaldehyde (CAA). The method proposed is selective and sensitive with limits of detection at the nano-molar level. Analysis of urine and saliva samples by using this method is demonstrated. Adenine, guanine, cytosine, adenosine, guanosine, and cytidine were found in the range from 0...

This work describes an electrochemical sensor for the fast noninvasive detection of uric acid (UA) in saliva. The sensing material was based on a cobalt-containing Prussian blue analogue (Na2- x Co[Fe(CN)6 ]1- y , PCF). By optimizing the ratio of Co and Fe as 1.5 : 1 in PCF (PCF1.5,0 ), particles with a regular nanocubic morphology were formed. The calcination of PCF1.5,0 produced a carbon-coated CoFe alloy (CCF1.5 ), which possessed abundant defects and achieved an excellent electrochemical performance...

A novel fluorescence sensor based on a porphyrinic zirconium-based metal-organic framework, L-cysteine-modified PCN-222 (L-Cys/PCN-222), was developed to selectively recognize histidine enantiomers and sensitively detect Hg2+ . The dual-functional sensor was successfully prepared via the solvent-assisted ligand incorporation method and characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), 1 H nuclear magnetic resonance (1 H NMR) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, circular dichroism (CD), X-ray photoelectron spectroscopy (XPS), and nitrogen adsorption-desorption analyses...

This study presents a novel approach for the detection of carbofuran (CBF) insecticide by systematically exploring a calix[4]arene-derived fluorescence probe, CouC4S, functionalized with two coumarin-labelled cystamine linkages at the narrow edge of the calix[4]arene platform. The proposed method showed a fluorescence "signal - off" effect when CBF binds with CouC4S by quenching the fluorescence intensity of CouC4S. Its limit of detection was as low as 5.55 μM according to the emission study. The working concentration range for this ligand was observed to be up to 5-65 μM...

Using silver nitrate as the silver source and sodium borohydride as the reducing agent, we synthesized negatively charged silver nanoparticles (AgNPs). Subsequently, the AgNPs solution was mixed with positively charged lead ions, resulting in AgNPs aggregation via electrostatic interactions. This led to a color change in the solution from yellow to purple and eventually to blue-green. Our study focused on a colorimetric method that exhibited high selectivity and sensitivity in detecting cysteine using AgNPs-Pb2+ as a sensing probe...

Microfluidic technology has great advantages in the precise manipulation of micro-nano particles, and the hybrid microfluidic separation technology has attracted much attention due to the advantages of both active and passive separation technology at the same time. In this paper, the hydrophoresis sorting technique is combined with the dielectrophoresis technique, and a dielectrophoresis-assisted hydrophoresis microdevice is studied to separate blood cells. By using the dielectrophoresis force to change the suspension position of the cells in the channel, the scope of the hydrophoresis device for sorting particles is expanded...

Herein, a magnetic bead-based chemiluminescence assay is reported to detect type IV collagen (col-IV) in serum samples. Magnetic beads (MBs) exhibit biocompatibility. Taking advantage of this property, they were conjugated with the col-IV antibody. For the determination of col-IV, the interaction of the col-IV sample, anti-(col-IV)-alkaline phosphatase (anti-(col-IV)-ALP) and anti-col-IV-magnetic beads (anti-(col-IV)-MBs) was performed to generate chemiluminescence. Under the optimized conditions, the developed method displayed good linearity in the concentration range of 20-2000 ng mL-1 with the limit of 0...

A simple and inexpensive method is presented to efficiently integrate light sheet illumination in a microfluidic chip for dark-field microscopic tracking and sizing of nanoparticles. The basic idea is to insert an optical fiber inside a polydimethylsiloxane (PDMS) elastomer microfluidic chip and use it as a cylindrical lens. The optical fiber is in this case no longer seen as only an optical waveguide but as a ready-made micro-optical component that is inexpensive and easy to source. Upon insertion, the optical fiber stretches the PDMS microchannel walls, which has two effects...

In previous reports, we described a PCR cycle control approach in which the hybridization state of optically labeled L-DNA enantiomers of the D-DNA primers and targets determined when the thermal cycle was switched from cooling to heating and heating to cooling. A consequence of this approach is that it also "adapts" the cycling conditions to compensate for factors that affect the hybridization kinetics of primers and targets. It assumes, however, that the hybridization state of the labeled L-DNA analogs accurately reflects the hybridization state of the D-DNA primers and targets...

Sartans, as a class of antihypertensive drugs, pose a threat to human health when illegally added to herbal beverages. It is crucial to detect sartans in herbal beverages. We have developed a highly sensitive monoclonal antibody against candesartan (CAN), olmesartan medoxomil (OLM), and irbesartan (IRB), with 50% inhibitory concentrations (IC50 ) that were obtained via indirect enzyme-linked immunosorbent assay (ic-ELISA) as 0.178 ng mL-1 , 0.185 ng mL-1 , and 0.262 ng mL-1 against CAN, OLM, and IRB, respectively...

The CN bond isomerization/modulation as a fluorescence signalling mechanism was explored by studying the photophysical properties of conformationally restricted molecules. From the beginning, the CN bond isomerization method has attracted the attention of researchers owing to its simplicity, high selectivity, and sensitivity in fluorescence evaluation. Continuous developments in the field of sensing using CN bond-containing compounds have been achieved via the customization of the isomerization process around the CN bond in numerous ways, and the results were obtained in the form of specific discrete photophysical changes...

Carbon dot (CD)-based fluorimetric sensors have attracted immense attention for the detection of metal ions. Among the available works in this direction, more than 70% of the studies reported the detection of Fe3+ through luminescence quenching. Ferric ions are significant species from environmental and biological point of view. Excited-state electron transfer from carbon dots to ferric ions is suggested as the reason for the luminescence quenching. However, to date, no solid proof was provided to demonstrate this electron transfer process...

Carotenoids are yellow, orange, and red pigments commonly found in plants. In leaves, these molecules are essential for photosynthesis, but they also play a major role in plant growth and development. Efficiently monitoring concentrations of specific carotenoids in plant tissues could help to explain plant responses to environmental stressors, infection and disease, fertilization, and other conditions. Previously, Raman methods have been used to demonstrate a correlation between plant fitness and the carotenoid content of leaves...

The presence of paraquat in the environment poses a danger to human health, leading to a growing demand for an uncomplicated and highly responsive method to detect paraquat. This work reports a new, simple, and sensitive colorimetric aptasensor based on the designed aptamers containing 1-5 paraquat binding sites (R1-R5) in combination with gold nanoparticles (AuNPs). Although the aptamers with more binding sites exhibited greater paraquat interaction capability, the aptasensor based on the R3 aptamer showed the highest detection sensitivity for paraquat in a linear range of 5-50 nM with a limit of detection of 1...