Fast Dispersive Liquid-Liquid Microextraction Based on Temperature Switching Deep Eutectic Solvent as A Green Extractant

With the development of research, it was found that the dispersive liquid-liquid microextraction (DLLME) was limited by the tedious extraction process and toxic extractant. A thermo-switchable deep eutectic solvent (DES) was applied to the DLLME as a green extractant in this paper. The DES can be dispersed and aggregated by shaking and heating in the water during the extraction process due to the surfactant and thermo-switchable properties, which shortened the extraction time as low as 5 minutes. The feasibility of the developed method was verified using 4 organophosphorus pesticides and 5 pyrethroids as targets in simulated water samples, which showed good precision (RSD%, 0.8-9.7, n=3) and low detection limit (0.16-0.81 µg L−1, S/N = 3) under the optimal extraction conditions. This method was used to detect the pesticide content in four natural rivers in Xi'an, and the recoveries of these spiked samples at three concentrations levels were among 81–113%. This is the first time to combine the toxic-free and thermo-switchable properties of DES in DLLME to proposes a simple, fast, effective, and green pretreatment method.

Improvement of field-deployable metagenomic virus detection by a simple pretreatment method.

As both the current COVID-19 pandemic and earlier pandemics have shown, animals are the source for some of the deadliest viral pathogens, which can spread to humans. Therefore, early detection at the point of incidence is crucial to both prevent and understand the threats posed to human health from pathogens in animal reservoirs. Often, the exact genetic nature of these zoonotic pathogens is unknown and advanced laboratory facilities do not exist in most field settings and therefore the development of methods for unbiased metagenomic and point of incidence detection is crucial in order to identify novel viral pathogens in animals with zoonotic and pandemic potential. Here we addressed some of these issues by developing a metagenomic Nanopore next-generation sequencing (mNGS) method for nucleic acids extracted from clinical samples from patients with SARS-CoV-2. To reduce the non-RNA viral genetic components in the samples, we used DNase pretreatment in a syringe followed by filtration and found that these pretreatments increased the number of SARS-CoV2 reads by > 500-fold compared with no pretreatment. The simple protocol, described here, allows for fast (within 6 hours) metagenomic detection of RNA viruses in biological samples exemplified by SARS-CoV-2 detection in clinical throat swabs. This method could also be applied in field settings for point of incidence detection of virus pathogens, thus eliminating the need for transport of infectious samples, cold storage and a specialized laboratory.

Potential Application of Pin-to-Liquid Dielectric Barrier Discharge Structure in Decomposing Aqueous Phosphorus Compounds for Monitoring Water Quality

Here, we proposed a pin-to-liquid dielectric barrier discharge (DBD) structure that used a water-containing vessel body as a dielectric barrier for the stable and effective treatment of aqueous solutions in an open atmosphere. To obtain an intense pin-to-liquid alternating current discharge using a dielectric barrier, discharge characteristics, including the area and shape of a ground-plate-type electrode, were investigated after filling the vessel with equivalent amounts of water. Consequently, as the area of the ground electrode increased, the discharge current became stronger, and its timing became faster. Moreover, we proposed that the pin-to-liquid DBD reactor could be used to decompose phosphorus compounds in water in the form of phosphate as a promising pretreatment method for monitoring total phosphorus in water. The decomposition of phosphorus compounds using the pin-to-liquid DBD reactor demonstrated excellent performance—comparable to the thermochemical pretreatment method—which could be a standard pretreatment method for decomposing phosphorus compounds in water.

Validation of an HPLC Method for Pretreatment of Steviol Glycosides in Fermented Milk

Steviol glycosides are used in food and beverages worldwide as natural sweeteners, serving as a low-calorie sugar substitute. The acceptable daily intake of steviol is 0–4 mg/kg body weight. The rising demand for dairy products has led to a corresponding increase in the use of steviol glycosides in such products. Therefore, it is important to analyze the levels of steviol glycosides in dairy products. Dairy products have high fat contents and unique emulsion characteristics, conferred by a mixture of fat globules, casein micelles, whey proteins, and numerous other small molecules. These characteristics may interfere with the estimation of steviol glycoside levels; therefore, dairy samples require pretreatment. We aimed to develop an objective test for measuring the levels of steviol glycosides through the development of an efficient pretreatment method. In this study, the steviol glycoside content in dairy products was evaluated by using various methods, and an optimal pretreatment method was determined. We used high-performance liquid chromatography to assess the selectivity, linearity, limit of detection, limit of quantification, accuracy, precision, and recovery rate. Calibration curves were linear in the range of 1–50 mg/kg, with a coefficient of determination of ≥0.999. The limit of detection and limit of quantification were in the ranges of 0.11–0.56 and 0.33–1.69 mg/kg, respectively. The relative standard deviation (%) represents the precision of a measurement. The RSD relative standard deviationof recovery varied between 0.16% and 2.83%, and recovery of the analysis varied between 83.57% and 104.84%. These results demonstrate the reliability of the method for measuring the steviol glycoside content. This method can be used for the simple pretreatment of steviol glycosides and can provide an accurate determination of steviol glycoside content in emulsified food matrices, such as dairy products.

Pretreatment of Natural Lignocellulose With Inorganic Salts Improves Ligninase Production Fermented By Aspergillus Fumigatus

This work screened out the optimal conditions for pretreatment of natural lignocellulose with inorganic salts and provided a simple, easy-to-operate, low-cost, clean and efficient pretreatment method for the efficient degradation of natural lignocellulose by strains. The results showed that the optimal pretreatment inorganic salt was FeCl2 with a concentration of 11%, pretreatment at 60°C for 48 h, and the solid-liquid ratio was 1:11 (g/mL). According to the characterization results, after pretreatment of FeCl2 solution, the smooth and dense structure of natural lignocellulose surface became rough and irregular, and surface fiber bundles showed spalling and fracture. Subsequently, the enzymes produced by solid-state fermentation of Aspergillus fumigatus were easier to enter the interior, which increased the contact area between materials and enzymes, and increased the amount of enzymatic loads, thereby improving the biodegradation effect.

Enhanced the Efficiency of Enzymatic Hydrolysis on Wheat Straw via Freeze-thawing Pretreatment

This research was investigated to enhance the efficiency of enzymatic hydrolysis on wheat straw via freeze-thawing pretreatment, and to find the physicochemical structural changes after this pretreatment. Results show that, this pretreatment enhances the enzymatic hydrolysis efficiency of cellulose and hemicellulose, and hemicellulose is more susceptible to this pretreatment. The highest enzymatic hydrolysis efficiency of cellulose and hemicellulose was 57.06% and 70.66% occurred on -80℃, 24 h and -10℃, 24 h pretreated samples, with an improvement of 2.23 and 3.13 folds of control. SEM images exhibited that transverse cracks appeared before longitudinal cracks as pretreated conditions aggravated, and holes can be found on every sample after this pretreatment. FTIR and XRD analysis implied that freeze-thawing pretreatment had effect both on the crystalline and amorphous regions, and disrupted the hydrogen bonds among them. This study provided a physical pretreatment method to improve the efficiency of enzymatic hydrolysis on wheat straw.