Dispersive Solid-Liquid Extraction Coupled with LC-MS/MS for the Determination of Sulfonylurea Herbicides in Strawberries

Colorimetric - Fluorescence - Photothermal tri-mode sensor array combining the machine learning method for the selective identification of sulfonylurea pesticides

Though cholinesterase-based method could detect two types of pesticides (organophosphorus and carbamate), they had weak sensing on sulfonylurea pesticides. In our previous work, the peroxidase-like reaction system of nanozyme - H2O2 - TMB showed selective detection of sulfonylurea pesticides, but the single-signal output sensing platform was easily affected by complex matrix background, cross-contamination and human error. Therefore, this work used colorimetric, photothermal, and fluorescent signals of the nanozyme reaction as sensing units for the detection of pesticides. This is the first time that photothermal signals have been used to construct a sensor array. When the concentration of interfering substances was 25 times that of pesticides, the method was still unaffected and had excellent selectivity and anti-interference performance. Meanwhile, a concentration-independent differentiation mode was established based on the K-nearest neighbor (KNN) algorithm. The pesticides were detected and distinguished with 100% accuracy. This work contributed to the detection of sulfonylurea pesticides in complex environmental/food matrices, bridging the gap of existing pesticide detection methods and providing an effective method for food safety detection.

Facile and selective recognition of sulfonylurea pesticides based on the multienzyme-like activities enhancement of nanozymes combining sensor array

Traditional identification methods based on cholinesterase inhibition are limited to recognizing organic phosphorus and carbamate esters, and their response to sulfonylurea pesticides is weak. Residual sulfonylurea pesticides can pose a threat to human health. So, it is very important to develop an effective, rapid and portable method for sulfonylurea pesticides detection. Herein, we first found that sulfonylurea pesticides have activity-enhancing effects on copper-based nanozymes, and then combined them with the array technology to construct a six-channel sensing array method for selectively identifying sulfonylurea pesticides and detecting total concentration of sulfonylurea pesticides (the limit of detection was 0.03 µg/mL). This method has good selectivity towards sulfonylurea pesticides. In addition, a smartphone-based colorimetric paper sensor analysis method was developed to achieve the on-site detection of the total concentration of sulfonylurea pesticides. And this array can also be used for individual differentiation (1-100 µg/mL). Our work not only investigates the specific responses of copper-based nanozymes to sulfonylurea pesticides, but also develops a simple method that contributes to directly detect sulfonylurea pesticides at the source of pollution, providing insights for further research on sulfonylurea pesticides detection and filling the gap in pesticide residue studies.

A novel Zn2+-coordination fluorescence probe for sensing HPPD inhibitors and its application in environmental media and biological imaging

Mesotrione, topramezone, tembotrione, and sulcotrione are four types of 4-hydroxyphenylpyruvate dioxidase (HPPD) inhibitor herbicides that are extensively employed in agricultural practices, but their usage also leads to environmental pollution and poses risks to human health. A probe (E)-1-((2-(pyridin-2-yl) hydrazineylidene) methyl) naphthalen-2-ol (CHMN) based on chelation enhancement (CHEF) effect synthesized. CHMN was first chelated with Zn2+ to form a probe system with green, which can be further used to detect mesotrione, topramezone, tembotrione and sulcotrione in complicated environment. CHMN-Zn2+ detection of four pesticides was accurate, with an excellent linear relationship between 0 and 100 μM. The detection limits were LODmesotrione = 7.79 μM, LODtopramezone = 1.91 μM, LODtembotrione = 1.38 μM and LODsulcotrione = 2.43 μM. The detection time is 1 min, and it is successfully applied in real water sample and bioimaging. This work can provide a novel method for studying the migration and behavior of environmental pollutants.

A Review on Recent Innovations of Pretreatment and Analysis Methods for Sulfonylurea Herbicides

Sulfonylurea herbicides (SUHs) are widely used in agriculture because of their low dosage, low cost, and high selectivity. However, due to improper use and lack of effective management, their residues pose a threat to the human health through environment and food pollution. Therefore, there is a need for simple, quick, economical, and effective methods to analyze SUHs in plant-derived foods, crops, and environmental samples. The present article presents a comprehensive review of the pretreatment and analytical technologies used for SUHs in various sample matrices, focusing on the developments since 2010. The main pretreatment methods include liquid-liquid extraction, solid-phase extraction, QuEChERS, and different microextraction methods, whereas analytical methods mainly include liquid chromatography coupled with different detectors, capillary electrophoresis, among others. In addition, the present study also compared the advantages and disadvantages of the methods and the future development is prospected.

An alternative analytical strategy based on QuEChERS and dissolvable layered double hydroxide dispersive micro-solid phase extraction for trace determination of sulfonylurea herbicides in wolfberry by LC-MS/MS

In this work, a combination of QuEChERS and dispersive micro-solid phase extraction (D-μ-SPE) based on dissolvable layered double hydroxide (LDH) has been established for preconcentration and enrichment of sulfonylurea herbicides (SUHs) in wolfberry samples. The QuEChERS was used for extraction and purification of SUHs, followed by D-μ-SPE for further enrichment of targeted analytes to obtain superior extraction performance. Dissolvable LDH nanosheets were used as absorbents, thus eliminating the elution step needed in traditional D-μ-SPE. The main influence experimental variables including pH of sample solution, amount of LDH, vortex time and volume of acidic solution were optimized in detail. Under the optimized conditions, the proposed method shows high precision (RSDs < 12.7%), low limits of detection (0.01-0.5 ng/g) and limits of quantitation (0.1-2.0 ng/g), acceptable recovery (80.1%-97.1%), thus making it a good alternative analytical strategy for the determination of SUHs residues at the low nanogram per gram range with desirable sensitivity.

Determination of Residual Triflumezopyrim Insecticide in Agricultural Products through a Modified QuEChERS Method

A rapid and simple analytical method for triflumezopyrim, a new class of mesoionic insecticides and commercialized molecules from DuPont, was developed with a modified QuEChERS method. The pH adjustment was used to improve the extraction efficiency of acetonitrile solvent, and dispersive solid-phase extraction was employed for the clean-up process. The five selected food commodities were used to verify the present optimized method, which displayed good linearity with an excellent correlation coefficient (R² = 0.9992–0.9998) in the 0.003–0.30 mg/kg calibration range. The method limits of detection (LOD) and quantification (LOQ) were determined to be a value of 0.003 and 0.01 mg/kg, respectively. The mean recovery for the triflumezopyrim was in the 89.7–104.3% range. The relative standard deviations were ≤9.8% for intra- (n = 5) and inter-day (n = 15) precisions at concentrations of 0.01, 0.1, and 0.5 mg/kg in the five representative samples. The matrix effect has been calculated to confirm the effect during ionization of the analyte in the UPLC-MS/MS. The matrix effects of the instrumental analysis showed that triflumezopyrim was less susceptible to matrices. The proposed analytical method in this study has effectively improved the accuracy, selectivity, and sensitivity for the determination of triflumezopyrim in agricultural commodities; therefore, it can serve as a reference method for the establishment of maximum residue limits (MRLs).

Rapid MSPD-LC-MS/MS Procedure for Determination of Pesticides in Potato Tubers

The program of potato protection recommended by the producers of agrochemicals requires application: thiamethoxam, lambda-cyhalothrin, deltamethrin, rimsulfuron and metalaxyl. Therefore, there is a risk that these pesticides are present in tubers, thus posing a toxicological risk to the consumer. In this respect, it is necessary to monitor the presence of these compounds in edible plants. Therefore, the aim of this paper was to develop a novel, simple and robust analytical procedure for simultaneous determination of above-mentioned pesticides in potato tubers. To develop an analytical procedure that fulfills SANTE demands, quick, easy, cheap, effective, rugged and safe method and matrix solid phase dispersion technique were investigated. The final determination was conducted by liquid chromatography with tandem mass spectrometry. The obtained experimental data were analyzed by analysis of variance. For the extraction of analytes, matrix solid phase dispersion with octadecyl sorbent and methanol as eluent was chosen, since it provides the validation parameters according to SANTE requirements (recovery: 77-111%, relative standard deviation: 1-10%, limit of quantification: 0.9-5.0 μg/kg). This innovative analytical procedure is a practical analytical tool, which was successfully proven by applying it for target pesticides determination in potato tuber samples of different varieties randomly chosen at local markets.

Multiresidue method for determining multiclass acidic pesticides in agricultural foods by liquid chromatography-tandem mass spectrometry

A reliable multiresidue method was developed for determining multiclass acidic pesticides in cereal grains, legumes, vegetables, and fruits. The target pesticides comprise 75 compounds, including phenoxy acid, sulfonylurea, imidazoline, and triazolopyrimidine herbicides, with acidic dissociation constant (pK_a) values of 1.9-5.9. The method includes extraction with acidified acetonitrile, salting out, cleanup with octadecyl silica and primary secondary amine cartridges, and subsequent liquid chromatography-tandem mass spectrometry. The analytical performance of the developed method was validated for nine foods (i.e., brown rice, soybeans, peanuts, spinach, cabbage, eggplant, potatoes, apples, and oranges) at a concentration of 0.01 mg kg^-1. Because matrix effects were negligible for most pesticide and food combinations, solvent-based calibration curves were used for quantification purposes. Most of the target compounds exhibited satisfactory analytical performance with trueness values of 70-100% and relative standard deviations below 14%. The high selectivity of the developed method was evidenced by the absence of interfering peaks near those of the target analytes. With the exception of 1-naphthaleneacetic acid, for which linearity was observed at 2.5-100 ng mL^-1, linear calibration curves were constructed for the target compounds in the 1-100 ng mL^-1 range, with coefficients of determination exceeding 0.995. The limits of detection were 3 μg kg^-1 or below in the examined matrices. The results demonstrate that the developed method is suitable for monitoring acidic pesticides in a variety of foods.

Development and Application of a Multi-Residue Method to Determine Pesticides in Agricultural Water Using QuEChERS Extraction and LC-MS/MS Analysis

Agricultural water is closely linked to surface and ground water as well as soil; hence, ensuring its safety is an important endeavor. We used the “quick, easy, cheap, effective, rugged, and safe” (QuEChERS) method to analyze multi-residue pesticides in agricultural water by using a combined-sorbent-based clean-up procedure. Among the various sorbents examined, clean-up using ENVI-Carb combined with a primary secondary amine sorbent delivered the highest recovery of multi-residue pesticides (>93.9%). While the developed method showed satisfactory linearity (R2 > 0.9991), precision, and specificity, recovery was low for pyrazolate (29.1%) and thidiazuron (59.2%). The limits of detection and quantification for the 55 pesticides targeted in this study were in 0.02–3.0 μg L−1 and 0.1–9.9 μg L−1, respectively. The developed method was used to identify and quantify multi-residue pesticides during sample analysis. The results suggest that the QuEChERS method employing a combination of ENVI-Carb and another sorbent can be applied for the effective analysis of multi-residue pesticides in agricultural water.

Analytical methods to analyze pesticides and herbicides

This paper reviews studies published in 2019, in the area of analytical techniques for determination of pesticides and herbicides. It should be noted that some of the reports summarized in this review are not directly related to but could potentially be used for water environment studies. Based on different methods, the literatures are organized into six sections, namely extraction methods, electrochemical techniques, spectrophotometric techniques, chemiluminescence and fluorescence methods, chromatographic and mass spectrometric techniques, and biochemical assays. PRACTITIONER POINTS: Totally 141 research articles have been summarized. The review is divided into six parts. Chromatographic and mass spectrometric techniques are the most widely used methods.

Preparation of polydopamine-coated, graphene oxide/Fe3 O4 - imprinted nanoparticles for selective removal of sulfonylurea herbicides in cereals

BACKGROUND

Sulfonylureas are potentially toxic broad-spectrum herbicides. They pose a persistent threat to food safety and the environment. It is therefore important to develop a rapid and efficient pretreatment and detection method to prevent their harmful effects on human health.

RESULTS

In the present work, a novel and highly selective absorbent for chlorosulfuron (CS) detection was prepared by the simple self-polymerization of dopamine on the surface of magnetic graphene oxide using a CS template. The resultant imprinted nanoparticles (MGO@PDA-MIPs) were characterized by transmission electron microscopy, X-ray diffraction, vibrating-sample magnetometry, thermogravimetric analysis, and nitrogen adsorption-desorption. The adsorption experiments demonstrated that the MGO@PDA-MIPs have excellent selectivity with regard to CS, with a high imprinting factor of 3.41 compared with a non-imprinted polymer. The nanoparticles rapidly achieve adsorption equilibrium and efficient desorption because there are numerous binding sites on the thin polydopamine imprinting layer. Under optimized conditions, the MGO@PDA-MIPs can be used to detect sulfonylurea residues in cereal samples by magnetic solid phase extraction coupled with high performance liquid chromatography (HPLC). The nanoparticles have a satisfactory recovery rate (80.65-101.01%) with a relative standard deviation (RSD) of less than 7.15%, and a limit of detection with regard to CS of 1.61 μg kg^-1 (S/N = 3). They can also be re-used at least seven times.

CONCLUSION

The MGO@PDA-MIPs have outstanding recognition performance, and can be prepared by a facile, single-step, and environmentally friendly process. They therefore have excellent potential for the recognition and separation of trace sulfonylurea herbicides in complex matrices. © 2020 Society of Chemical Industry.