Flowerlike Ni-NiO composite as magnetic solid-phase extraction sorbent for analysis of carbendazim and thiabendazole in edible vegetable oils by liquid chromatography-mass spectrometry

Preparation of W-N-C single atom catalyst and Cu3(HHTP)2 metal-organic framework dual-decorated graphene nanoplatelet flexible electrode arrays for the rapid detection of carbendazim in vegetables

It is highly desirable to develop a low-cost and rapid detection method for trace levels of carbendazim fungicide residues, which would be beneficial for improving human health and mitigating environmental issues. Herein, isolated single tungsten atoms were implanted onto well-organized metal-organic framework (MOF)-derived N-doped carbons to form W-N-C single-site heterojunctions with ultrahigh electrocatalytic activity. The coupling of W-N-C with Cu3(HHTP)2, an electronically conductive MOF with a large surface area and porous structure, exhibited enhanced electrocatalytic performance for the oxidation of carbendazim (CBZ) when they were used for decorating graphene nanoplatelet flexible electrode arrays fabricated via template-assisted scalable filtration. A wide linear range (3.0 nM-50 μM) with an ultra-low detection limit of 0.97 nM and fast response was achieved for CBZ analysis. Moreover, the sensing platform has been utilised to monitor CBZ levels in vegetable samples with satisfactory recovery rates of 97.2-102% and a low relative standard deviation of 1.9%.

Integration of a biocompatible metal-phenolic network and fluorescence microspheres as labels for sensitive and stable detection of carbendazim with a lateral flow immunoassay

High fluorescence intensity microspheres such as aggregation-induced emission fluorescence microspheres (AIEFM) have improved the sensitivity of lateral flow immunoassay (LFIA). The preparation of immune probes in LFIA usually adopts the chemical coupling strategy with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide for antibody coupling, which has the problems of low coupling efficiency, tedious coupling process, and poor repeatability. A biocompatible metal-phenolic network (MPN), which contains large amounts of phenols and galloyl groups, could easily, quickly, and stably couple with antibodies. Herein, we proposed a strategy based on MPN modification on ultrabright AIEFM surface as a novel label for the rapid detection of carbendazim. The limit of detection of AIEFM@MPN-LFIA was 0.019 ng/mL, which was 4.9 times lower than that of AIEFM-LFIA. In spiked samples, the average recoveries of AIEFM@MPN-LFIA ranged from 80% to 118% (coefficient of variation <13.45%). Therefore, AIEFM@MPN was a promising signal label that could improve the detection performance of LFIA.

Optimization of QuEChERS cleanup for quantification of γ-oryzanol in vegetable oils by UHPLC-MS/MS

This study was based on QuEChERS cleanup coupled with UHPLC-MS/MS for the determination of γ-oryzanol compounds in vegetable oils. Several parameters of QuEChERS and UHPLC-MS/MS were studied for purification and detection of γ-oryzanol compounds in oil samples. Under the optimized conditions, the whole pretreatment procedure could be accomplished within 10 min without tedious procedure, larger volume of organic solvent and complicated apparatus. The limit of detections and the limit of quantifications for γ-oryzanol compounds were ranging from 0.1-0.3 µg kg-1 and 0.4-1.0 µg kg-1, respectively. Satisfactory recoveries of all analyts were ranging from 72.2 % to 101.3 %, and the intra-day and inter-day precision were less than 10.6 %. The validation indicated that rice band oil and corn oil were rich in 24-mCAF, CAF, β-SIF, CMF and STF. The QuEChERS-UHPLC-MS/MS simultaneously quantified five γ-oryzanol compounds in lipid matrices and assessed the nutritional and functional substances of vegetable oils.

Cobalt-Modified Black Phosphorus Nanosheets-Enabled Ferrate (VI) Activation for Efficient Chemiluminescence Detection of Thiabendazole

The development of chemiluminescence-based innovation sensing systems and the construction of a sensing mechanism to improve the analytical performance of compounds remain a great challenge. Herein, we fabricated an advanced oxidation processes pretreated chemiluminescence (AOP-CL) sensing system via the introduction of cobalt-modified black phosphorus nanosheets (Co@BPNs) to achieve higher efficient thiabendazole (TBZ) detection. Co@BPNs, enriched with lattice oxygen, exhibited a superior catalytic performance for accelerating the decomposition of ferrate (VI). This Co@BPNs-based ferrate (VI) AOP system demonstrated a unique ability to selectively decompose TBZ, resulting in a strong CL emission. On this basis, a highly selective and sensitive CL sensing platform for TBZ was established, which exhibited strong resistance to common ions and pesticides interference. This was successfully applied to detecting TBZ in environmental samples such as tea and kiwi fruits. Besides, the TBZ detection mechanism was explored, Co@BPNs-based ferrate (VI) AOP system produced a high yield of ROS (mainly 1O2), which oxidized the thiazole-based structure of TBZ, generating chemical energy that was transferred to Co@BPNs via a chemical electron exchange luminescence (CIEEL) mechanism, leading to intense CL emission. Notably, this study not only proposed an innovative approach to enhance the chemical activity and CL properties of nanomaterials but also offered a new pathway for designing efficient CL probes for pollutant monitoring in complex samples.

O-nitrobenzyl Caged Molecule Enables Photo-controlled Release of Thiabendazole

Pesticides are essential in agricultural development. Controlled-release pesticides have attracted great attentions. Base on a principle of spatiotemporal selectivity, we extended the photoremovable protective group (PRPG) into agrochemical agents to achieve controllable release of active ingredients. Herein, we obtained NP-TBZ by covalently linking o-nitrobenzyl (NP) with thiabendazole (TBZ). Compound NP-TBZ can be controlled to release TBZ in dependent to light. The irradiated and unirradiated NP-TBZ showed significant differences on fungicidal activities both in vitro and in vivo. In addition, the irradiated NP-TBZ displayed similar antifungal activities to the directly-used TBZ, indicating a factual applicability in controllable release of TBZ. Furthermore, we explored the action mode and microcosmic variations by SEM analysis, and demonstrated that the irradiated NP-TBZ retained a same action mode with TBZ against mycelia growth.

A SERS aptasensor based on a flexible substrate for interference-free detection of carbendazim in apple

Non-destructive and interference-free monitoring of pesticide residue on the surface of fruits is still a challenge. Herein, a SERS aptasensor based on a flexible substrate was established for effective carbendazim (CBZ) detection on apple peel. In this sensor, electrospun PVDF/CQDs film served as a flexible supporting substrate. AuNS@Ag was liquid-liquid self-assembled on the PVDF/CQDs film to form a uniform and highly active SERS substrate. During the detection process, aptamers specifically capture the CBZ molecules, while nitrile-mediated Raman tag (MMBN) linked to AuNPs provided optical anti-interference signals. The results showed that the developed sensor had high sensitivity, selectivity, reproducibility, and stability for CBZ detection. Importantly, the flexibility of the SERS substrate helped the sensor realize non-invasive CBZ detection at a concentration as low as 1.20 ng/cm2 on apple peel, which is much lower than the maximum residue limits of CBZ in apples.

ZIF-67-Derived Co/N-Doped Carbon-Functionalized MXene for Enhanced Electrochemical Sensing of Carbendazim

Herein, ZIF-67-derived Co and N-doped carbon (Co/NC) particle-modified multilayer MXene (MXene@Co/NC) was developed as remarkable electrode material for carbendazim (CBZ) detection. MXene as a substrate provides an excellent conductive framework and plentiful accessibility sites. Co/NC particles embedding in MXene can not only prevent the interlayer stacking of MXene but also contribute a great deal of metal catalytic active sites and finally improve the adsorption and catalytic properties of the composite. Accordingly, the MXene@Co/NC electrode displays excellent electrocatalytic activity toward CBZ oxidation. Experimental parameters such as pH value, accumulation time, MXene@Co/NC modification volume and constituent materials' mass ratios were optimized. Under optimal conditions, the as-prepared sensor based on MXene@Co/NC holds a broad linearity range from 0.01 μM to 45.0 μM with a low limit of detection (LOD) of 3.3 nM (S/N = 3, S means the detection signal, while N represents the noise of the instrument). Moreover, the proposed sensor displays excellent anti-interference ability, superior reproducibility, excellent stability, and successfully achieves actual applications for CBZ detection in a lettuce sample.

Review of Characteristics and Analytical Methods for Determination of Thiabendazole

Thiabendazole (TBZ) is a fungicide and anthelmintic drug commonly found in food products. Due to its toxicity and potential carcinogenicity, its determination in various samples is important for public health. Different analytical methods can be used to determine the presence and concentration of TBZ in samples. Liquid chromatography (LC) and its subtypes, high-performance liquid chromatography (HPLC) and ultra-high-performance liquid chromatography (UHPLC), are the most commonly used methods for TBZ determination representing 19%, 18%, and 18% of the described methods, respectively. Surface-enhanced Raman spectroscopy (SERS) and fluorimetry are two more methods widely used for TBZ determination, representing 13% and 12% of the described methods, respectively. In this review, a number of methods for TBZ determination are described, but due to their limitations, there is a high potential for the further improvement and development of each method in order to obtain a simple, precise, and accurate method that can be used for routine analysis.

Miniaturized kapok fiber-supported liquid extraction for convenient extraction of pesticide residues in vegetable oils: Determination of organochlorine pesticides as a proof-of-concept study

In this paper, a miniaturized kapok fiber-supported liquid extraction (mini-KF-SLE) method was proposed for selective extraction of pesticide residues in vegetable oils. The natural kapok fiber was used as an inert oil support material based on its hydrophobic and lipophilic properties, and the extraction device was conveniently constructed by loading 15 mg of kapok fiber at the lower middle part of a 1-mL pipette tip. The vegetable oil sample (150 mg) without any pretreatment was directly loaded, followed by the addition of 150 μL of acetonitrile (ACN) as the extractant. After static extraction for 30 min, the extractant was pipetted out with a pipettor. As the proof of concept, it was applied for extracting eight organochlorine pesticides (OCPs) from vegetable oils and the eluate was analyzed by gas chromatography-electron capture detector (GC-ECD). Under optimized conditions, the extraction recoveries of OCPs were calculated to be in ranges of 35.8-79.5%. The satisfied quantitation ability was verified by the established method with coefficients of determination (R²) being greater than 0.99. The limits of detection (LODs) were in ranges of 2.0-50.0 ng/g. The relative recoveries were in ranges of 78.3-117.0% with the inter-/intra-day relative standard deviation (RSD) both being less than 13.3%. The potential of mini-KF-SLE to extract other kinds of pesticides was further verified by the successful extracting three triazole pesticides in vegetable oils with good extraction recoveries (>41.4%). The proposed mini-KF-SLE in combination with instrument detection techniques has the great potential in the low-cost and high-throughput determination of various pesticide residues in vegetable oils.

A simple co-precipitation sorbent-based preconcentration method for the analysis of fungicides in water and juice samples by high-performance liquid chromatography coupled with photodiode array detection

A magnesium hydroxide co-precipitation sorbent-based method in the presence of an anionic surfactant (e.g., sodium dodecylbenzenesulfonate) and high-performance liquid chromatography were used to preconcentrate and analyze fungicides in water and apple juice samples. The preconcentration procedure can be accomplished in a single step based on the co-precipitation of target fungicides and magnesium chloride in the presence of surfactant in a sodium hydroxide solution (pH 11) and a white precipitate gel was simply obtained after centrifugation. The property of precipitate phase was subsequently characterized using Fourier-transform infrared spectroscopy, scanning electron microscopy, and X-ray diffractometry. Under the optimum conditions, the developed method exhibited good sensitivity, with an enrichment factor of 11–18 and limits of detection of approximately 1–5 μg/L for water samples and 7–10 μg/L for apple juices. High reproducibility was achieved with a relative standard deviation of less than 11%, and a good recovery range of 72% to 120% was also obtained. The proposed method was shown to be a simple preconcentration procedure for concentrating fungicides in the samples investigated.

Kapok fiber-supported liquid extraction for convenient oil samples preparations: A feasibility and proof-of-concept study

In this study, a novel kapok fiber-supported liquid extraction (KF-SLE) method was developed for conveniently extracting analytes from oil samples. Natural kapok fiber without any pretreatment was directly used as an oil support medium. The extraction device was conveniently constructed by directly packing some kapok fibers into a syringe tube. Due to the fibrous property of the kapok fiber, no filter plate was needed. The cost of a KF-SLE device was as low as 0.5 CNY. The KF-SLE process was conveniently conducted using a simple three-step protocol: (1) the oil sample without any pretreatment including dilution was added directedly; (2) then, the oil-immiscible extractant was added; (3) after waiting a certain time for static extraction, the extractant was eluted out by pressing the kapok fibers with the syringe plunger. The extractant could be directly transferred for subsequent instrumental detection. For the feasibility and proof-of-concept study, the method was applied to quantify four synthetic flavor chemicals in edible oils. Satisfied quantification results were obtained with the correlation coefficient (R²) being greater than 0.996, the relative recoveries ranging from 92.90% to 107.53% and intra- and inter-day RSDs being less than 7.56%. All in all, for the first time, the SLE technique was expanded to process oil samples and the method has the characteristics of low cost, environmental friendliness, high sample processing throughput and ease of automation, offering a promising approach for edible oil sample preparations.