Dispersive Liquid-Liquid Microextraction Combined with Microwave Demulsification for Determination of FAME Residuals in Biodiesel Wastewater.

Biodiesel consists of various fatty acid methyl esters (FAMEs) that are mainly produced through transesterification of plant oil or animal fat. It is essential for biodiesel to be purified utmostly to meet its product standard before being traded, while the universal purification method has been water washing. However, water washing inevitably causes the residual of FAMEs in wastewater, which represents a loss of industrial profits.

Differentiating wild, lake-farmed and pond-farmed carp using stable isotope and multi-element analysis of fish scales with chemometrics.

Stable carbon (δC) and nitrogen (δN) isotope ratios and multi-element signatures of pooled fish scales were used to differentiate wild, lake-farmed and pond-farmed carp from Dongting Lake, China. Fish scales were found to be important archives for the dietary history and trophic level of wild and farmed fish, indicating their food sources. δC and δN values of pond-farmed carp scales were comparatively enriched to wild and lake-farmed carp due to their animal protein-derived feeds.

Differentiating Westlake Longjing tea from the first- and second-grade producing regions using ultra high performance liquid chromatography with quadrupole time-of-flight mass spectrometry-based untargeted metabolomics in combination with chemometrics.

There are numerous articles published for geographical discrimination of tea. However, few research works focused on the authentication and traceability of Westlake Longjing green tea from the first- and second-grade producing regions because the tea trees are planted in a limited growing zone with identical cultivate condition. In this work, a comprehensive analytical strategy was proposed by ultrahigh performance liquid chromatography-quadrupole time-of-flight mass spectrometry-based untargeted metabolomics coupled with chemometrics.

Mechanism of interactions between organophosphorus insecticides and human serum albumin: Solid-phase microextraction, thermodynamics and computational approach.

Organophosphates insecticides (OPs) are one of the major environmental pollutants and their interaction with human serum albumin (HSA) has been shown to have significant effects on their bioavailability which is related to toxicokinetics and toxicodynamics in human body. In this research, solid-phase microextraction methods were developed to analyse the free concentrations of three OPs (chlorpyrifos, parathion-methyl and malathion) in buffered HSA solution and that provide a useful method for the determination of binding affinity constants (K), binding forces and binding location. Polydimethylsiloxane fibers were selected for analysing the free concentrations of OPs, with an external calibration approach.

Study of photodegradation kinetics of aflatoxins in cereals using trilinear component modeling of excitation-emission matrix fluorescence data.

In this work, a smart analytical strategy that combines excitation-emission matrix (EEM) fluorescence detection with alternating trilinear decomposition (ATLD) algorithm was developed for fast, on-line and interference-free study on the photodegradation kinetics of aflatoxin B (AFB) and aflatoxin G (AFG) in rice and wheat under UV-Vis light (λ = 250-500 nm) treatment. With the aid of prominent "second-order advantage" of ATLD method, pure fluorescence signals of two targeted analytes can be directly resolved out from heavily overlapping spectral environment and accurately quantified even in the presence of unknown matrix interferences. Cereal samples in kinetic processing of photodegradation were detected without complex pretreatment steps except for a simple extraction using methanol/water solution (4:1, v/v), which solves the problem facing varied matrix interferences in the case of on-line monitoring of aflatoxins.

High-throughput determination of fungicides in grapes using thin-film microextraction coupled with liquid chromatography-tandem mass spectrometry.

A high-throughput and environmentally friendly method based on 96-well plate thin-film microextraction was established to determine 14 fungicides in grapes and grape juice using liquid chromatography-tandem mass spectrometry. The thin-film microextraction optimized method consisted of 60 min of extraction at pH 6.0 with the addition of sodium chloride (2-5%).

Comparison of three second-order multivariate calibration methods for the rapid identification and quantitative analysis of tea polyphenols in Chinese teas using high-performance liquid chromatography.

Retention time shifts in second-order calibration-assisted chromatographic analysis seriously impact the modeling and quantitative accuracies in complex systems. In this work, three second-order methods, i.e.

Long-Term Agricultural Effects on the Authentication Accuracy of Organic, Green, and Conventional Rice Using Isotopic and Elemental Chemometric Analyses.

Organically farmed rice is believed to be healthier, safer, and eco-friendlier than its conventionally farmed counterparts and sells for a premium price in global markets. Deliberate mislabeling of organic rice has become a critical consumer concern in China and elsewhere, and there is an increased risk of buying fraudulent organic rice in the market place. In this study, stable isotopic and multielemental analysis combined with chemometrics was used to differentiate organically farmed rice from green and conventional rice in a 4-year experimental field trial from 2014 to 2017.

Dissipation behavior, residue distribution and risk assessment of three fungicides in pears.

Background: Fungicides are often applied to pears before they are kept in storage facilities. The scientific application of pesticides can reduce unnecessary exposure, which in turn could benefit both humans and the environment.

Results: We investigated dissipation behavior and residue distribution, and conducted risk assessments for prochloraz, pyraclostrobin, and tebuconazole in pears stored under different conditions using ultra-performance liquid chromatography (UPLC).

Target-based metabolomics for fast and sensitive quantification of eight small molecules in human urine using HPLC-DAD and chemometrics tools resolving of highly overlapping peaks.

Chemometrics multivariate calibration coupled with high performance liquid chromatography-diode array detection (HPLC-DAD) analytical strategy was applied for fast and sensitive quantification of the eight small molecules (uric acid, creatinine, tyrosine, homovanillic acid, hippuric acid, indole-3-acetic acid, tryptophan and 2-methylhippuric acid) in human urine. The objective of this work was to get the successful resolution of the complex matrix with minimum experimental time in the presence of highly overlapping peaks, of distortions in the time and baseline aspects among chromatograms, and of the presence of unknown and background interferences. All the analysis were based on a short C18 column with the chromatographic system operating in isocratic mode and all analytes can be successfully quantified within 6 min.

Geographical traceability of Chinese green tea using stable isotope and multi-element chemometrics.

Rationale: Deliberate and fraudulent origin mislabeling of Chinese green tea motivated by large price differences often brings significant food safety risks and damages consumer trust. Currently, there is no reliable method to verify the origin of green tea produced in China. Stable isotope and multi-element analyses combined with statistical models are widely acknowledged as useful traceability techniques for many agro-products, and could be developed to confirm the geographical origin of Chinese green tea and, more importantly, combat illegal green tea mislabeling and fraud.

Influence of leaf age, species and soil depth on the authenticity and geographical origin assignment of green tea.

Rationale: Stable isotope fractionation occurring during leaf growth provides internal characteristics for identifying the geographical origin, traceability and authentication of tea. Studying the influence of leaf age, species and the relationship with the cultivated soil may reveal previously undocumented stable isotope fractionation mechanisms, and provide a deeper understanding of the physiological isotopic effects on the tractability and authentication accuracy of green tea to combat mislabeling and fraudulent conduct.

Methods: A total of 36 pairs of young (one bud with one leaf) and mature growth (older leaf) samples from two species of Longjing tea (Longjing #43 and Colonial cultivar) and corresponding cultivation soil samples from two different depth layers (0-20 cm and 20-40 cm) were collected in Westlake district, Hangzhou, Zhejiang province, China.

Differentiating Organically Farmed Rice from Conventional and Green Rice Harvested from an Experimental Field Trial Using Stable Isotopes and Multi-Element Chemometrics.

Chemometric methods using stable isotopes and elemental fingerprinting were used to characterize organically grown rice from green and conventionally grown rice in experimental field trials in China. Carbon, nitrogen, hydrogen, and oxygen stable isotopes as well as 26 other elements were determined. Organic rice was found to be more depleted in C than green or conventionally grown rice because of the uptake of enriched C from carbon dioxide and methane respiring bacteria and more enriched in N because of the volatilization of the nitrogen from the urea and ammonium of the animal manures used to manufacture the organic composts.

Tracking Changes of Hexabromocyclododecanes during the Refining Process in Peanut, Corn, and Soybean Oils.

Hexabromocyclododecanes (HBCDs) are harmful compounds, which could be taken up by plants and occur in vegetable oils. In this study, we systematically tracked the changes of HBCDs during different refining processes in peanut, corn, and soybean oils in China. The refining processes were efficient at removing the concentrations of total HBCDs (∑HBCDs), although the levels did increase for peanut and corn oils during the neutralization and bleaching steps.

The dissipation and risk assessment of 2,4-D sodium, a preharvest anti-fruit-drop plant hormone in bayberries.

Preharvest fruit-drop is a challenge to bayberry production. 2,4-D sodium as a commonly used anti-fruit-drop hormone on bayberry can reduce the yield loss caused by preharvest fruit-drop. The persistence and risk assessment of 2,4-D sodium after applying on bayberries were investigated.

Improved Discrimination for Brassica Vegetables Treated with Agricultural Fertilizers Using a Combined Chemometric Approach.

Multielement and stable isotope (δ(13)C, δ(15)N, δ(2)H, δ(18)O, (207)Pb/(206)Pb, and (208)Pb/(206)Pb) analyses were combined to provide a new chemometric approach to improve the discrimination between organic and conventional Brassica vegetable production. Different combinations of organic and conventional fertilizer treatments were used to demonstrate this authentication approach using Brassica chinensis planted in experimental test pots. Stable isotope analyses (δ(15)N and δ(13)C) of B.

The effect of biochar and crop straws on heavy metal bioavailability and plant accumulation in a Cd and Pb polluted soil.

Biochar derived from various materials has been investigated with regard to its ability to decrease the bioavailability of heavy metals in contaminated soils, and thus reduce their potential to enter the food chain. However, little attention has been given to the adsorption capacity of untreated crop straws, which are commonly used as a biochar feedstock, especially in soils. Hence, this study was conducted to investigate the effect of crop straws on heavy metal immobilization and subsequent heavy metal uptake by maize and ryegrass in a soil artificially polluted by Cd and Pb.

Variations in the natural ¹⁵N abundance of Brassica chinensis grown in uncultivated soil affected by different nitrogen fertilizers.

To further investigate the method of using δ(15)N as a marker for organic vegetable discrimination, the effects of different fertilizers on the δ(15)N in different growing stages of Brassica chinensis (B. chinensis) grown in uncultivated soil were investigated with a pot experiment. B.

Effect of different fertilizers on nitrogen isotope composition and nitrate content of Brassica campestris.

The effect of different fertilizers on the δ(15)N value, nitrate concentration, and nitrate reductase activity of Brassica campestris and the δ(15)N value of soil has been investigated through a pot experiment. The δ(15)N mean value of B. campestris at the seedling stage observed in the composted chicken treatment (+8.