A simple, quick and environmentally friendly microwave-assisted synthesis method was developed to produce MoS2 nanoparticles (MoS2NP) for the preconcentration of thallium. The characteristics of the synthesized MoS2NP were validated by x-ray diffraction (XRD) and scanning electron microscopy (SEM). The determination of thallium was achieved with MoS2NP based preconcentration and a flame atomic absorption spectrophotometer (MoS2NP-PM-FAAS). A detection limit of 14.6 µg/kg was achieved for thallium using the optimum conditions by the MoS2-PM-FAAS method. The developed method provided an improvement in the detection power of the FAAS system by approximately 20-fold. The applicability of the method was validated with tea samples through spike recovery experiments.

Peak detection is an important step in mass spectrometry as accurately identifying characteristic peaks is key to data analysis. In order to address the issue of false peak detection, while simultaneously ensuring accurate detection of weak and overlapped peaks, this paper introduces an improved algorithm for mass spectrometry integrating weighted continuous wavelet transform with particle swarm optimization-based Otsu (WWTPO). The algorithm applies the weighted continuous wavelet transform (WCWT) to compress the frequency spectrum signal into a smaller scale range, which allows for the acquisition of more distinct and informative peak information. Moreover, the algorithm employs the particle swarm optimization (PSO) algorithm to iteratively evaluate the optimal image segmentation threshold, which addresses the challenge of inaccurate Otsu image segmentation. The method was applied to detect simulated peaks as well as matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) datasets. The performance evaluation was conducted using receiver operating characteristic (ROC) curves, F1 measure and F-scores. Through comparison with continuous wavelet transform (CWT) and genetic algorithm-based threshold segmentation (WSTGA), multi-scale peak detection (MSPD) and CWT and image segmentation (CWT-IS), the results demonstrate that WWTPO exhibits excellent performance in peak detection. The determination of 4-isopropyltoluene also demonstrates that WWTPO has excellent practical application. This method not only maintains a low false peak identification rate but also detects more weak peaks and overlapping peaks, further improving the accuracy and efficiency of peak detection in mass spectrometry.

Near-infrared (NIR) spectroscopy is a nondestructive technique extensively employed in various fields. Despite its advantages, near-infrared spectroscopy still faces significant challenges due to the intricate physical and chemical phenomena that arise from the interaction between light and matter. This interaction typically results in light absorption and scattering, leading to the NIR signal containing comprehensive information about these phenomena’s interactions. Accurate determination of and in cement raw meal requires minimizing scattering effects from the spectrum, but selecting an appropriate pretreatment technique is often challenging. In this paper, we enhance the predictive ability of NIRS for determining the four oxides in cement raw meal by implementing sequential preprocessing through orthogonalization (SPORT). The SPORT method uses sequential orthogonal partial least squares (SO-PLS) to integrate data blocks obtained from different preprocessing techniques. We compare our method with conventional pretreatment methods for determining the content of four oxides in raw materials of cement using near-infrared spectroscopy. The results suggest that the SPORT method exhibits commendable calibration performance and distinctive characteristics. Moreover, SPORT demonstrates significant preprocessing selectivity, making it effective in addressing the challenges associated with complex interactions in near-infrared spectral analysis. In conclusion, the utilization of SPORT sequential pretreatment in near-infrared spectroscopy shows promising results for enhancing the accuracy and efficiency of determining oxide content in raw materials of cement. The findings of this study help promote the application of near-infrared spectroscopy in the cement industry, especially quality control. Further exploration of the SPORT method’s potential in other materials analysis fields may open new avenues for nondestructive techniques in various scientific disciplines.

This work highlights using a domestic microwave oven to determine moisture in fish tissues. Also, it compares it with other gravimetric methods established employing a conventional oven (AOAC) and infrared radiation. The optimization of the microwave method was performed utilizing a two-level full factorial design. The AOAC method, which uses a temperature of 105 °C, requires 130 min for the analysis, while the microwave method can be done in 2 min. Intraday and interday tests evaluated the precision of both methods. The determination of the moisture of the fishes Cynoscion acoupa, Argyrosomus regius, Carassius auratus, Sardinella longiceps, Thunnus, Merluccius, Caranx latus, and Brachyplatystoma vaillantii was performed using the microwave and AOAC methods. The analysis of variance and the paired t-test showed no significant differences in the results obtained using these two methods. Also, moisture in other fish tissues was quantified using microwave radiation.

A lab-on-a-tip (LOT) has been constructed as a sensing platform for the detection of lead using a disposable pipette tip. The LOT has been constructed with optical fiber spectroscopy where the inside wall of a pipette tip is modified with a polymeric inclusion membrane (PIM) immobilized with dithizone as a chemical sensor for Pb(II) in herbal samples. Under optimal conditions, the LOT determined Pb(II) across a linear concentration range from 1.9 to 20 mg/L with a detection limit of 0.621 mg/L. The analysis of samples shows good agreement with the flame atomic absorption spectroscopy (FAAS).

Polygonum Amplexicaule Radix is a traditional Chinese medicine for promoting blood circulation and removing blood stasis, which is often used to treat thrombotic diseases. However, its potential anticoagulant active ingredients have been unexplored. In this study, a method for rapid screening of anticoagulant active ingredients from P. amplexicaule by affinity-ultrafiltration (AUF) and high-performance – tandem mass spectrometry (HPLC-MS/MS) was established, which using thrombin as an affinity receptor target. 5 potential anti-thrombin active components were screened: gallic acid, procyanidin B2-3''O-gallate, 11-O-galloylbergenin, (-)-epicatechin gallate and di-galloyl-O-bergenin by AUF and HPLC-MS/MS. The inhibitory ability of these active ingredients to thrombin was confirmed by in vitro activity experiments and molecular docking, hence justifying that P. amplexicaule is a traditional Chinese medicine with excellent anticoagulation effects. Meanwhile, it has been shown that AUF-MS could be a way rapid screening for active substances.

Detection and removal of trace amounts of toxic organic and inorganic pollutants in water and wastewater is important for the entire ecosystem. The development of new materials for the determination and removal of contaminants is constantly necessary. Layer double- hydroxides (LDHs) form a broad class of nanomaterials that represent anionic clay composite material used in research and development applications to protect the environment from pollutants. LDH structures functionalized with carbon-based materials are promising adsorbents in the extraction of organic and inorganic pollutants through adsorption and ion exchange mechanisms due to their increased versatility. This review describes recent studies on carbon-containing structure-based LDH composites used in the determination and removal of organic and inorganic pollutants in water and wastewater. Thus, it will lead to the realization of new studies for the determination and removal of different pollutants in other matrices besides water samples of LDHs.

Carbon quantum dots (CQDs) were derived from saponin and introduced into polyacrylamide hydrogel to prepare a novel bifunctional material (CQDs@HG). This hydrogel emitted strong blue fluorescence under ultraviolet light (365 nm) and exhibited stable adsorption and detection of iron(III) in water samples. The morphological characteristics, chemical composition, Fe3+ adsorption performance, and optical properties of CQDs@HG were characterized. Depending upon the Fe3+ concentration, CQDs@HG exhibited different quenching effects to allow Fe3+ determination. The limit of detection was 0.115 μM, and the adsorption was as high as 12.13 mg/g. The mechanism was due to both static and dynamic quenching. Notably, the sensor based on CQDs@HG successfully determined Fe3+ in water samples, with spiked recoveries between 95.32% and 103.11%. When combined with software image analysis, the sensor semi-quantitatively determined Fe3+ in the field. This fluorescent hydrogel provides a reference for constructing portable sensors for monitoring hazardous substances in water.

Viola dalatensis, belonging to the Violaceae family, is an endemic species to Vietnam. The present study aimed to determine phenolic compounds in extracts from aerial parts of the plant species using high performance liquid chromatography with diode-array detection (HPLC-DAD). In addition, free radical scavenging and bovine albumin denaturation inhibition assays were performed to evaluate the antioxidant and in vitro anti-inflammatory activities of the extracts. Most of the phenolic compounds in the methanolic extract were detected at the greatest concentrations compared to the other extracts, which was also supported by the highest total phenolic content (26.70 ± 0.1059 mg GAE/g). In general, the antioxidant activities of the methanolic and ethanolic extracts were found to be stronger than those of the other extracts. The aqueous extract exhibited the most potent inhibitory effect on albumin denaturation (IC50 = 90.39 ± 8.415 µg/mL), comparable with that of diclofenac. Through principal component analysis, 88.60% of the total variance in the phenolic dataset was explained. The correlation analysis showed that chlorogenic acid, ferulic acid, epigallocatechin gallate, rutin, and kaempferol may play important roles in antioxidant activity while gallic acid could contribute to in vitro anti-inflammatory activity of the extracts. The findings of this study provide the first evidence of the bioactive compounds present in V. dalatensis and shed light on the potential health-promoting properties linked to its aerial parts.

Pyrolysis-gas chromatography-mass spectrometry (pyr-GC-MS) is emerging as a promising alternative for the detection and quantification of microplastic pollution. For a robust quantification it is essential to improve our understanding of interferences in the pyrolysis of microplastics. Here we investigate the effects of different soil matrices, mainly differing by their organic carbon content (Corg, 1.0–13.6%), and of the polymer molecular weight (Mw) on the pyr-GC-MS analysis of polystyrene (PS) microplastics. In addition, we evaluated the effectiveness of adding poly(4-fluorostyrene) (PSF) as internal standard to circumvent the matrix effects. The three main markers of PS pyrolysis, i.e., styrene, styrene-dimer and styrene-trimer, were monitored. The ratio between the dimer and the trimer significantly varied between the matrices and tended to decrease with the increasing of the Corg in the soil, mainly due to an increased trimer formation. A strong matrix effect affected the slope of the calibration curves by 2 to 8-fold and was correlated with the Corg in the soils. This effect was mitigated when the areas of the markers were normalized by the area of the corresponding marker of PSF. PS of low Mw (Mw 35,000) presented a reduced formation of the three markers compared to PS of high Mw (Mw 400,000), and styrene-dimer was proportionally less formed than the other two markers. Differences in the slopes of calibration curves depended on the marker chosen, highlighting the relevance of selecting the pyrolysis marker in the quantification of microplastics using pyr-GC-MS.