Significant role of supercritical fluid chromatography - mass spectrometry in improving the matrix effect and analytical efficiency during multi-pesticides residue analysis of complex chrysanthemum samples

Determination of chlordimeform and its metabolite residue in milk by gas chromatography-tandem mass spectrometry

Herein, the determination of chlordimeform and its metabolite 4-chloro-2-methylaniline residue in milk was performed for the first time using gas chromatography-tandem mass spectrometry (GC-MS/MS). Samples were extracted using acetonitrile, and cleaned using a quick, easy, cheap, effective, rugged, and safe (QuEChERS) method. Separation was performed using the DB-17 MS column. It was detected in a selected reaction monitoring (SRM) mode and quantified using a matrix-matched isotope internal standard method. Under optimal conditions, a good linear relationship was observed in the concentration range of 10-200 µg/kg. The limit of quantitation was 10.0 µg/kg. The spiked recoveries for the target substance ranged from 84.5 % to 107.3 %, with relative standard deviations (RSD) of <7.2 %. The spiked samples were further confirmed by gas chromatography-quadrupole-Orbitrap high-resolution mass spectrometry (GC-Orbitrap HRMS). The combined method resulted in high accuracy and sensitivity and was suitable for the determination of chlordimeform and its metabolite 4-chloro-2-methylaniline residue in milk.

Optimization of QuEChERS method for determination of pesticide residues in vegetables and health risk assessment

The present study focused on the optimization of the QuEChERS extraction method for the determination of 61 pesticide residues and associated health risk assessment in 144 samples of commonly consumed vegetables, viz., eggplant, cabbage, green chilli, okra, and tomato. The samples were collected between January and April 2022 from three different districts within Gujarat, India. The QuEChERS method was optimized and utilized for the extraction of samples. The samples were analyzed by UHPLC-q-TOF/MS and GC-MS/MS. The modified QuEChERS method was successfully validated, and the obtained results were satisfactory as per the 2021 SANTE guidelines. The residue analysis of the vegetable samples showed that about 4% of total samples contained single pesticide residues. Pesticide residues below the quantitation limit (BQL) were observed in eggplant, cabbage, and okra samples. In total, 15.62% (n = 5) samples of green chilli showed the presence of pesticides such as azoxystrobin, bifenthrin, cypermethrin, fenpropathrin, and propargite whereas 3% (n = 1) tomato samples contained cyfluthrin. In total, 97.22% of the samples had residues that were below the European Union Maximum Residue Limit (EU MRL). Two samples of green chilli had pesticide residues above EU MRL. The Hazard Index (HI) and Hazard Quotient (HQ) were used to assess the health risks associated with green chilli and tomato consumption. The HI and HQ values for adolescents and adults were found to be less than 1. The modified QuEChERS method was found to be easy and effective and can be implemented for routine sample analysis. The study revealed the presence of pesticide residues in tomato and green chilli samples. Further, the outcome provided information pertaining to current pesticide status, concluding that consumption of these commodities is unlikely to pose any health risk, though long-term monitoring studies focusing on dietary health risk assessment must be initiated.

Acetylcholine triggered enzymatic cascade reaction based on Fe7S8 nanoflakes catalysis for organophosphorus pesticides visual detection

BACKGROUND

Organophosphorus pesticides (OPs) play important roles in the natural environment, agricultural fields, and biological prevention. The development of OPs detection has gradually become an effective strategy to avoid the dangers of pesticides abuse and solve the severe environmental and health problems in humans. Although conventional assays for OPs analysis such as the bulky instrument required analytical methods have been well-developed, it still remains the limitation of inconvenient, inefficient and lab-dependence analysis in real samples. Hence, there is an urgent demand to develop efficient detection methods for OPs analysis in real scenarios.

RESULTS

Here, by virtue of the highly efficient catalytic performance in Fe7S8 nanoflakes (Fe7S8 NFs), we propose an OPs detection method that rationally integrated Fe7S8 NFs into the acetylcholine (ACh) triggered enzymatic cascade reaction (ATECR) for proceeding better detection performances. In this method, OPs serve as the enzyme inhibitors for inhibiting ATECR among ACh, acetylcholinesterase (AChE), and choline oxidase (CHO), then reduce the generation of H2O2 to suppress the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) that catalyzed by Fe7S8 NFs. Benefiting from the integration of Fe7S8 NFs and ATECR, it enables a sensitive detection for OPs (e.g. dimethoate). The proposed method has presented good linear ranges of OPs detection ranging from 0.1 to 10 μg mL-1. Compared to the other methods, the comparable limits of detection (LOD) of OPs are as low as 0.05 μg mL-1.

SIGNIFICANCE

Furthermore, the proposed method has also achieved a favorable visual detection performance of revealing OPs analysis in real samples. The visual signals of OPs can be transformed into RGB values and gathered by using smartphones, indicating the great potential in simple, sensitive, instrument-free and on-site analysis of pesticide residues in environmental monitoring and biosecurity research.

Pesticide residue detection technology for herbal medicine: current status, challenges, and prospects

The domains of cancer therapy, disease prevention, and health care greatly benefit from the use of herbal medicine. Herbal medicine has become the mainstay of developing characteristic agriculture in the planting area increasing year by year. One of the most significant factors in affecting the quality of herbal medicines is the pesticide residue problem caused by pesticide abuse during the cultivation of herbal medicines. It is urgent to solve the problem of detecting pesticide residues in herbal medicines efficiently and rapidly. In this review, we provide a comprehensive description of the various methods used for pesticide residue testing, including optical detection, the enzyme inhibition rate method, molecular detection methods, enzyme immunoassays, lateral immunochromatographic, nanoparticle-based detection methods, colorimetric immunosensor, chemiluminescence immunosensor, smartphone-based immunosensor, etc. On this basis, we systematically analyze the mechanisms and some of the findings of the above detection strategies and discuss the challenges and prospects associated with the development of pesticide residue detection tools.

Matrix effect in bioanalytical assay development using supercritical fluid chromatography-mass spectrometry

Matrix effect (ME) is commonly caused by coelution of compounds with target analytes, resulting in either suppression or enhancement of analyte ionization. Thus, to achieve the desired accuracy, precision, and sensitivity, ME needs to be evaluated and controlled during bioanalytical method development. As the application of supercritical fluid chromatography-mass spectrometry (SFC-MS) for analysis of biological samples has increased, ME using SFC-MS has also been investigated with a focus on the difference in ME in SFC-MS compared to other chromatographic techniques used for achiral separation in biological samples. Here, we provide a summary of the status of ME evaluation and mitigation in SFC-MS methods. This review presents an overview of the phenomenon of ME and methods for evaluating ME in bioanalysis. Next, the factors that can impact ME in SFC-MS-based bioanalytical methods are discussed in detail with an emphasis on SFC. A literature review of the evaluation of ME in targeted bioanalytical methods using SFC-MS is included at the end. Robust instrumentation, effective sample preparation, and superb separation selectivity are the foundations of reliable analytical methods as well as the ability to mitigate detrimental ME in SFC-MS methods.

Comprehensive multiresidue chromatographic methods for monitoring pesticides in agricultural areas and corresponding plant protection zones

This article reports a comprehensive analytical method for the identification and quantification of a broad range of pesticides in green plant crops. The sample preparation method for pesticides involved an optimization of the QuEChERS-based extraction protocol, with sample mass, volume of added water, and the type of cleanup sorbent as variables. A sorbent combination based on ENVI-Carb and ChloroFiltr was examined. A highly efficient method was developed for the purification of plant extracts with 900 mg MgSO4, 150 mg PSA, and 15 mg ENVI-Carb at the d-SPE stage, combined with gas chromatography and liquid tandem mass spectrometry for the determination of 197 pesticides in crop plants containing chlorophyll. The method was validated in accordance with the requirements of international guidelines SANTE/11312/2021. The method was applied to quantify pesticide residues in 29 pairs of green crop plants and plants from the corresponding crop protection zone to verify whether the zones are effective barriers to prevent pesticides from penetrating outside agricultural areas. The number and types of agrochemical preparations were chosen by farmers. In total, more than 60 one- and several-component pesticide formulations were applied to the crops included in the study. The pesticide residues were detected in 21 crop samples and 3 samples from protection zones. Epoxiconazole, an active substance that was banned for use in 2021, was found in a spring barley sample. Based on the conducted research, the effectiveness of the protection zones has been clearly demonstrated, and it has been proven that environmental migration of pesticides and unauthorized agricultural practices pose a risk to ecosystems.

Spatiotemporal dynamics and modeling of thiacloprid in paddy multimedia systems with the effect of wetting-drying cycles

The widespread presence of thiacloprid (THI), a neonicotinoid, raises concerns for human health and the aquatic environment due to its persistence, toxicity, and bioaccumulation. The fate of THI in paddy multimedia systems is mainly governed by irrigation practices, but the potential impacts remain poorly documented. This study investigated the effects of water management practices on THI spatiotemporal dynamics in paddy multimedia systems by combining soil column experiments and a non-steady-state multimedia model. The results indicated the wetting-drying cycle (WDC) irrigation reduced THI occurrences in environmental phases (i.e., soil, interstitial water, and overlying water) and accelerated the THI loss through the THI aerobic degradation process. THI occurrences in the soil and water phases decreased from 18.8% for conventional flooding (CF) treatment to 9.2% for severe wetting-drying cycle (SW) treatment after 29 days, while the half-lives shortened from 11.1 days to 7.3 days, respectively. Meanwhile, the WDC decreased THI outflow from leakage water, which reduced the THI risk of leaching. There was no significant difference in THI plant uptake and volatilization between CF and WDC treatments. The mean proportions of THI fate in paddy multimedia systems followed the order: THI degradation (57.7%), outflow from leakage water (25.5%), occurrence in soil (12.4%), plant uptake (3.4%), occurrence in interstitial water (0.7%), occurrence in overlying water (0.3%), volatilization (<0.1%) after 29 days. The sensitivity analysis identified the soil organic carbon partition coefficient (KOC) as the most sensitive parameter affecting THI's fate. In addition, the topsoil layers of 0-4 cm were the main sink of THI, holding 67% of THI occurrence in the soil phase. The THI occurrence in interstitial water was distributed evenly throughout the soil profile. These findings made beneficial theoretical supplements and provided valuable empirical evidence for water management practices to reduce the THI ecological risk.

Evaluation of supercritical fluid chromatography coupled to tandem mass spectrometry for the analysis of pesticide residues in grain

A supercritical fluid chromatography-tandem mass spectrometry (SFC-MS/MS) technique was developed for the rapid and simultaneous detection of nine pesticides (carbendazim, isoprocarb, paclobutrazol, isoprothiolane, flusilazole, quinalphos, piperonylbutoxide, propargite, and bioresmethrin) in rice, wheat, and maize. The cereal samples were extracted with a solution of 0.5% acetic acid in acetonitrile and purified using quick, easy, cheap, effective, rugged, and safe method. The samples were characterized using multi-reaction monitoring and quantified with the external standard method. Excellent linearities (R2  > 0.9991) and limits of quantification (0.4-40.0 μg/kg) were established for all nine pesticides. Satisfactory pesticide recovery rates (62.2%-107.4%) were obtained at three standard concentrations (50, 100, and 200 μg/kg), with relative standard deviations in the range of 2.1%-14.3%. The results confirmed that the proposed method was suitable for the routine detection of these pesticides in grain samples. Compared with high-performance liquid chromatography-MS/MS, the overall test run time and the amount of solvent required were reduced by 66% and 90%, respectively, when SFC-MS/MS was applied. Therefore, the use of SFC-MS/MS permits a shorter run time and affords greater analytical efficiency, such that it is both economical and environmentally sustainable.

Highly sensitive determination of multiple pesticide residues in foods by supercritical fluid chromatography coupled with ion mobility quadrupole time-of-flight mass spectrometry

This experiment aimed to establish a green, simple and highly sensitive method (supercritical fluid chromatography (SFC) coupled with ion mobility quadrupole time-of-flight mass spectrometry (IM-Q-TOF/MS)) for the detection of multiple pesticides in foods. During the experiments, several important SFC parameters, such as stationary phase, modifier, make-up solution, back-temperature and back-pressure were optimized. Here, single-field collision cross section (CCS) values and multifield CCS values of 20 pesticides were examined by IM-Q-TOF/MS as highly specific parameters with excellent experimental precision. In addition, based on accurate mass matching and fragment ion comparison, mass fragments were obtained by IM-Q-TOF/MS, which elucidated the regularities of compound structure and characteristic fragment ions. Under the optimized conditions, satisfactory linearity (R2 ≥ 0.9989) and recoveries (79.60 % to 112.97 %) were obtained. The intra- and interday precisions were favorable, with RSDs lower than 4.91 and 7.65 %, respectively. Additionally, the method showed low limits of detection (0.1-8.8 ng/mL). The proposed method has been successfully applied to the highly sensitive detection of phenylurea herbicide, triazine herbicides, organophosphorus pesticide, pyrethroid insecticide and acaricide in yam and potato.

Plasma-Excited Nebulizer Gas-Assisted Electrospray Ionization: Enhancing the Sensitivity of Pesticide in Mass Spectrometry

Liquid chromatography-mass spectrometry (LC-MS) is widely used in the detection of pesticide residues. However, the detection sensitivity of low-polarity pesticides by commonly used electrospray ionization may be severely suppressed, which greatly affects the limit of detection and repeatability. Herein, a plasma-excited nebulizer gas-assisted electrospray ionization (PENG-ESI) device has been developed. By introducing the discharge plasma formed by Tesla coil into the electrospray nebulizer gas channel, the sensitivity of low-polarity pesticides was significantly increased while maintaining sensitivity to polar pesticides. Under the optimized conditions, the limit of detection for S-bioallethrin was achieved at the level of 100 pg/g with good linearity (R2 > 0.99) and precision (RSD ≤ 4.61%). The matrix effect of a series of spiked matrix samples is less than 13.1%. Finally, different pyrethroid pesticide residues were successfully analyzed without separation, highlighting that the technology has potential application prospects in food quality control, environmental monitoring, and other fields.

Phenolic-based non-ionic deep eutectic solvent for rapid determination of water soluble neonicotinoid insecticides in tea infusion

Challenges were raised to established analytical method for monitoring water soluble neonicotinoid insecticide (NEOs) residues in tea infusion. Phenolic-based non-ionic deep eutectic solvent (NIDES) composed by a mixture of DL-menthol and thymol (molar ratio of 1:3) was applied to achieve the determination of selected NEOs. Factors influenced extraction efficiency have been evaluated and molecular dynamics approach was conducted aming to provide a new insight to explain its extraction mechanism. It is found that Boltzmann averaged solvation energy of NEOs was negatively correlated with extraction efficiency. The method validation results indicated good linearities (R² ≥ 0.99), sensitive LOQs (0.05 μg L^-1), high precisions (RSD < 11%) and satisfactory recoveries (57.7%∼98%) at 0.05 μg L^-1 ∼ 100 μg L^-1. The intake risk of NEOs in tea infusion samples were acceptable which residues in range of 0.1 μg L^-1 ∼ 3.5 μg L^-1 for thiamethoxam imidacloprid and thiacloprid. This method showed advantages of rapid, green, and easy operation.

Fabrication of magnetic magnesium oxide cleanup adsorbent for high-throughput pesticides residue analysis coupled with supercritical fluid chromatography-tandem mass spectrometry

A rapid and accurate analytical method was established for multiple pesticide residues in complex matrices based on magnetic dispersive solid phase extraction (d-SPE) and supercritical fluid chromatography-tandem mass spectrometry (SFC-MS/MS). To develop an efficient magnetic d-SPE method, magnetic adsorbent modified with magnesium oxide (Fe₃O₄-MgO) was prepared via layer-by-layer modification and used as cleanup adsorbent for removal of interferences that contain a large number of hydroxyl or carboxyl groups in the complex matrix. The obtained Fe₃O₄-MgO coupled with 3-(N,N-Diethylamino)-propyltrimethoxysilane (PSA) and octadecyl (C18) were used as d-SPE purification adsorbents and their dosages were systematically optimized with Paeoniae radix alba as the matrix model. Combined with SFC-MS/MS, rapid and accurate determination of 126 pesticide residues in the complex matrix was achieved. Further systematic method validation showed good linearity, satisfactory recovery, and wide applicability. The average recoveries of the pesticides at 20, 50, 80, and 200 μg kg^-1 were 110, 105, 108, and 109%, respectively. The proposed method was applied to complex medicinal and edible root plants, such as Puerariae lobate radix, Platycodonis radix, Polygonati odorati rhizoma, Glycyrrhizae radix, and Codonopsis radix. The average recoveries of the pesticides at 80 μg kg^-1 in these matrices were 106, 106, 105, 103, and 105%, respectively with an average relative standard deviation range of 8.24-10.2%. The results demonstrated the feasibility and wide matrix applicability of the proposed method, which is promising for pesticide residue analysis in complex samples.

Recent advances in perovskite oxides for non-enzymatic electrochemical sensors: A review

Non-enzymatic electrochemical sensors with significant advantages of high sensitivity, long-term stability, and excellent reproducibility, are one promising technology to solve many challenges, such as the detection of toxic substances and viruses. Among various materials, perovskite oxides have become a promising candidate for use in non-enzymatic electrochemical sensors because of their low cost, flexible structure, and high intrinsic catalytic activity. A comprehensive overview of the recent advances in perovskite oxides for non-enzymatic electrochemical sensors is provided, which includes the synthesis methods of nanostructured perovskites and the electrocatalytic mechanisms of perovskite catalysts. The better sensing performance of perovskite oxides is mainly due to the lattice O vacancies and superoxide oxygen ions (O₂^2-/O^-), which are generated by the transfer of lattice oxygen to adsorbed -OH and have performed excellent properties suitable for electrooxidation of analytes. However, the limited electron transfer kinetics, stability, and selectivity of perovskite oxides alone make perovskite oxides far from ready for scientific development. Therefore, composites of perovskite oxides with other materials like graphitic carbon, metals, metal compounds, conducting organics, and biomolecules are summarized. Furthermore, a brief section describing the future challenges and the corresponding recommendation is presented in this review.

Determination of Multi-pesticides Residues in Jasmine Flower and Its Scented Tea

For minor crops such as jasmine, the lack of pesticide registration and maximum residue limits are important issues that need to be solved in order to facilitate trading and ensure food safety. Meanwhile, reliable and quick analytical methods for multi-pesticide residues in these commodities are few, but required by various stakeholders. In this study, a method for detecting twenty-five most frequently used pesticides in jasmine flower and its scented tea by multi-plug filtration cleanup and ultra-high-performance liquid chromatography-tandem mass spectrometry was developed and validated. The cleanup process was optimized and compared with the dispersive solid phase extraction procedure. The method was validated, showing that except for methomyl, recoveries of twenty-five pesticides were 64%-108%, with relative standard deviations (n = 5) of 0.33%-10%. The method was successfully applied to detect pesticide residues in marketed samples. The results showed that some flower and tea samples contained a combination of different pesticide residues.

Simultaneous Determination of 108 Pesticide Residues in Three Traditional Chinese Medicines Using a Modified QuEChERS Mixed Sample Preparation Method and HPLC-MS/MS

A rapid, efficient, simple, and high-throughput method for the simultaneous determination of 108 pesticide residues in three traditional Chinese medicines (TCMs) was established, comprising an improved QuEChERS method in combination with HPLC-MS/MS based on mixed samples. A quantity of 10 mL of acetonitrile was used as extraction solvent, and 10 mg of amino-modified multi-walled carbon nanotubes (MWCNTs-NH2) and 150 mg of anhydrous magnesium sulfate (MgSO4) were selected as sorbents for dispersive solid phase extraction. The performance of the method was verified according to the analytical quality control standards of SANTE/11813/2017 guidelines. With good linearity (R2 > 0.9984) in the range of 2−200 μg/L for all pesticides in the selected matrices, and good accuracy, precision, and high sensitivity, the recoveries were in the range of 70−120% for more than 95% of the pesticides, with a relative standard deviation (RSD) of less than 16.82% for all. The limit of detection (LOD) and limit of quantification (LOQ) of the method were 0.01−3.87 μg/kg and 0.07−12.90 μg/kg, respectively, for Fritillaria thunbergii Miq (F. thunbergii), Chrysanthemum Morifolium Ramat (C. morifolium), and Dendrobium officinale Kimura et Migo (D. officinale). The method was successfully applied to 60 batches of actual samples from different regions.

Magnetic polymer particles as a highly efficient and facile cleanup adsorbent for multi-pesticide residues analysis in aquatic products

A novel and efficient sample pretreatment procedure using magnetic particles was exploited for the determination of multi-pesticide residues in aquatic products. The magnetic adsorbent was prepared using divinyl benzene and N-vinyl pyrrolidone as functional monomers modified on the Fe₃O₄ @SiO₂. The obtained magnetic adsorbent, octadecylsilane sorbents, and graphitized carbon black were employed as effective adsorbents to remove matrix interferences in aquatic products, and their dosages were optimized. Satisfactory levels of accuracy and precision were procured under optimum conditions. The method limits of quantification ranged from 0.1 to 2.0 μg/kg. The analytical accuracy of the developed method for the analysis of multi-pesticide residues in freshwater and seafood products was validated. It was found to be suitable for the analysis of multi-pesticide residues in different types of aquatic products. Additionally, the method was successfully applied for the analysis of pesticide residues in fish samples obtained from aquaculture plants located in Zhejiang Province, China. The detected concentrations of pesticides ranged from 0.14 to 0.95 μg/kg. In general, this method shows promising application prospects for the rapid determination of multi-pesticide residues in aquatic products.

Reduction of pesticide residues in Chrysanthemum morifolium by nonthermal plasma-activated water and impact on its quality

This study investigated the efficiency of plasma-activated water (PAW) on the reduction of pesticides, namely, metribuzin and metobromuron, and the effect of PAW treatment on the quality of fresh chrysanthemums. The reduction efficiencies reached 74.3% for metribuzin and 38.2% for metobromuron after 240 s of PAW treatment. Compared with reverse osmosis (RO) water, PAW achieved significantly higher pesticide reductions because of its higher acidity, enhanced oxidizing ability, and increased formation of reactive species. Moreover, when compared with metobromuron, metribuzin was reduced more efficiently irrespective of the RO water or PAW treatments because of its higher water solubility, lower log octanol-water partition coefficient, and more oxidizable chemical structure. Additionally, the PAW treatment did not cause adverse changes to the chrysanthemums' color, total flavonoid content, radical scavenging, or metal chelating activities, but it did cause a slight decrease in the chrysanthemums' aroma compounds and total reducing power. This study successfully demonstrated the effectiveness of PAW for reducing pesticides in herbal flowers like chrysanthemums and reveals PAW's promising potential to treat foods with non-smooth surfaces.

[Rapid screening of 84 pesticide residues in dendrobium by Sin-QuEChERS Nano purification column with gas chromatography-tandem mass spectrometry]

A rapid screening method for 84 pesticide residues in dendrobium perfringens parent material with different polarities was developed using a Sin-QuEChERS Nano clean-up column combined with gas chromatography-tandem mass spectrometry (GC-MS/MS). The differences in extraction efficiency of the targets were compared with different extraction solvents (acetonitrile containing 1% acetic acid, acetone) and methods (immersion with or without water). The purification effect and extraction recoveries of Sin-QuEChERS Nano method and classical dispersive solid-phase extraction (dSPE), solid-phase extraction (SPE) and QuEChERS were systematically compared using Dendrobium nobile samples. The differences in matrix effects between the Sin-QuEChERS Nano method, which was more effective in purification, and the dSPE method were also analyzed. The purification effects of three commercially available Sin-QuEChERS Nano purification columns (simple matrix purification column, complex matrix purification column and herbal purification column) were compared. The applicability of the purification methods were also verified by using different parts of Dendrobium nobile samples (stems, leaves and flowers). From the results, it could be concluded that weighing 2.00 g and the samples in 5 mL of water for 20 min, followed by extraction with acetonitrile containing 1% acetic acid was more effective. The average extraction recovery of the target components by Sin-QuEChERS Nano purification method was 90.5%, which further identified Sin-QuEChERS Nano-Chinese medicine purification column as the preferred purification column for dendrobium purification. The target components were separated by a DB-1701MS quartz capillary column (30 m×0.25 mm×0.25 μm) with programmed temperature rise, detected by multiple reaction monitoring (MRM) mode, and quantified by matrix-matched solution external standard method. The GC-MS/MS assay was used for the methodological validation of the 84 representative pesticides within Dendrobium officinale and Dendrobium nobile was carried out by GC-MS/MS detection method. The results indicated that the targets showed excellent linear correlation in different scopes with correlation coefficients (r2) >0. 990. The limits of detection (LODs, S/N=3) of the method were 1.5 to 5.8 μg/kg, and the limits of quantification (LOQs, S/N=10) ranged from 5.0 to 15.0 μg/kg. The spiked recoveries of the target pesticides under different spiked levels were 68.7%-116.2%, and the relative standard deviations (RSDs, n=6) were less than 15%. Compared to other typical pretreatment methods, the Sin-QuEChERS Nano method provided better performance in terms of purification. The method not only effectively removed pigments, organic acids, and alkaline interferents, but also saved preparation time. Losses due to solvent transfer were also avoided and no further vortexing or centrifugation was required, making it a simplified and effective extraction and purification procedure. The method was sensitive, rapid, simple and reliable. It effectively improved the detection efficiency during the rapid screening of pesticides in dendrobium and presented a strong practical application value. In addition, the developed method could further expand the types of target pesticides and could be used to detect more pesticide residues in foods and Chinese herbal medicine. The established Sin-QuEChERS Nano method was used for the analysis of authentic samples. The applicability of the method was evaluated by analyzing a total of 80 samples collected from Anlong, Libo, Dushan, and Yanhe County in Guizhou Province. The types of samples included dendrobium maple, Dendrobium nobile (flowers, stems, leaves) and Dendrobium officinale (flowers, stems, leaves, powder, tablets). At least one pesticide residue was detected in 12 samples, with a detection rate of 15%. The five pesticides with higher detection rates and residues were chlorpyrifos (0.08-0.5 mg/kg), chlorothalonil (0.06-3.2 mg/kg), propanil zinc (0.03-0.15 mg/kg), methyl parathion (0.04-0.23 mg/kg) and cyhalothrin (0.10-2.68 mg/kg). Except for the pesticides in maximum residue limits (MRLs), the pesticide residues detected from dendrobium samples were below the limits set by Chinese national standard (GB 2763-2021) and local standard DBS 52/048-2020.

Determination of Tropomyosin in Shrimp and Crab by Liquid Chromatography–Tandem Mass Spectrometry Based on Immunoaffinity Purification

A UPLC-MS/MS method was developed for the detection of tropomyosin (TM) in shrimp and crab. After simple extraction, the samples were purified by immunoaffinity column and then digested by trypsin. The obtained sample was separated by Easy-nLC 1000-Q Exactive. The obtained spectrums were analyzed by Thermo Proteome Discoverer 1.4 software and then ANIQLVEK with high sensitivity was selected as the quantitative signature peptide. Isotope-labeled internal standard was used in the quantitative analysis. The method showed good linearity in the range of 5–5,000 μg/L with a limit of quantification (LOQ) of 0.1 mg/kg. The average recoveries were 77.22–95.66% with RSDs ≤ 9.97%, and the matrix effects were between 88.53 and 112.60%. This method could be used for rapid screening and quantitative analysis of TM in shrimp and crab. Thus, it could provide technical support for self-testing of TM by food manufacturers and promote further improvement of allergen labeling in China.

Research and Application of In Situ Sample-Processing Methods for Rapid Simultaneous Detection of Pyrethroid Pesticides in Vegetables

A novel rapid and cost-effective pre-processing method for the simultaneous determination of pyrethroid pesticides in vegetables has been developed and validated. The process of pesticide extraction was carried out by the QuEChERS (quick, easy, cheap, effective, rugged and safe) method combined with filtration by filter paper, and cleanup was carried out by the multi-plug-filtration-cleanup (m-PFC) method with no centrifuge program during the whole process. The pre-processing method is optimized for gas chromatography (GC). The process is convenient and time saving, requiring just a few seconds per sample. The recovery rate (70–120%), limit of detection (0.0001–0.007 mg/kg), precision (0.2–9.3%) and accuracy for each analyte were determined in 10 representative vegetables with good results. Finally, the feasibility of the developed method was further confirmed by the successful determination of pyrethroid-pesticide residues in pyrethroid-containing practical samples within the processing method coupled with thin-layer chromatography and a colloidal-gold test strip.

Preparation of lightweight daisy-like magnetic molecularly imprinted polymers via etching synergized template immobilization for enhanced rapid detection of trace 17β-estradiol

17β-estradiol (E2), as one of the pharmaceutical and personal care product, frequently contaminates environmental water as estrogen pollutant and possesses great risk to human survival as well as the sustainable development of the ecosystem. Herein, to achieve an effective adsorbent system for the selective removal of E2 from the environmental water, Fe₃O₄ nanoparticles are subjected to chemical etching to reduce the overall mass and then employed as carriers to prepare a novel type of lightweight daisy-like magnetic molecularly imprinted polymers (LD-MMIPs) adopting template immobilization strategy. The LD-MMIPs based etched magnetic nanoparticles not only exhibit light mass but also have plentiful imprinted sites in the etched channels, which significantly increases the adsorption capacity for E2. The daisy-like LD-MMIPs own strong magnetic responsiveness, well crystallinity, fast binding kinetics, high adsorption amount, and excellent selectivity. Moreover, combining with HPLC, the LD-MMIPs as adsorbents have been successfully used to specifically recognize and detect trace E2 in environmental water. Thus, the proposed LD-MMIPs with high adsorption capacity hold great potential in monitoring water pollution. Additionally, this work also provides an alternative strategy for improving the adsorption capacity of magnetic molecularly imprinted polymers through a convenient chemical etching technology.

Development of magnetic solid phase extraction using magnetic amphiphilic polymer for sensitive analysis of multi-pesticides residue in honey

A sensitive and time-saving method for the determination of multi-pesticide residues in honey was developed using magnetic solid phase extraction (MSPE) coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS). Magnetic polymer (N-vinyl pyrrolidone-divinyl benzene) (MVP-DB) was fabricated and employed as the adsorbent for extraction and enrichment of multi-pesticide residues in honey. MVP-DB contains lipophilic benzene ring, divinyl group, and hydrophilic pyrrolidone group. The good hydrophilic and hydrophobic structure of MVP-DB not only ensures sufficient dispersion in honey samples, but also enhances the ability to enrich target analytes. The predominant factors affecting the recoveries of analytes were systematically investigated, affording a rapid and highly efficient MSPE method. Under the optimal conditions, the method was verified, including the recovery, precision, linearity, sensitivity, and matrix effects. The results displayed that these pesticides showed good linearity in the range of 2-250 µg L^-1. The MLOQs were 0.5 µg kg^-1. The recoveries of pesticides in honey at the pre-spiked concentrations of 0.5-25 µg kg^-1 were 61.6%-112% with RSDs less than 18.2%. Hence, the developed method displayed good application prospect for the determination of multi-pesticide residues in honey samples.

A technical overview of supercritical fluid chromatography-mass spectrometry (SFC-MS) and its recent applications in pharmaceutical research and development

In this paper, we review the growing development and applications of supercritical fluid chromatography-mass spectrometry (SFC-MS) for the analysis of small molecular analytes and biomarkers in drug discovery. As an alternative chromatographic technique, SFC instrumentation and methodology have dramatically advanced over the last decade. Mass spectrometry (MS) provides the powerful detection capability as it couples with SFC. A growing number of SFC-MS/MS applications were reported over the last decade and the application areas of SFC-MS/MS is rapidly expanding. The first part of this review is devoted to the different aspects of SFC-MS development and recent technological advancements. In the second part of this review, we highlight the recent application areas in pharmaceutical research and development.

Rapid Screening of 350 Pesticide Residues in Vegetable and Fruit Juices by Multi-Plug Filtration Cleanup Method Combined with Gas Chromatography-Electrostatic Field Orbitrap High Resolution Mass Spectrometry

A new method for screening pesticide residues in vegetable and fruit juices by the multi-plug filtration cleanup (m-PFC) method combined with gas chromatography-electrostatic field orbitrap high resolution mass spectrometry(GC-Orbitrap/MS) was developed. The samples were extracted with acetonitrile, purified with m-PFC and determined by GC-Orbitrap/MS. Qualitative analysis was confirmed by retention time, accurate molecular mass and quantitative analysis were performed with the matrix standard calibration. It could eliminate matrix interference effectively. Eight kinds of typical samples (orange juice, apple juice, grape juice, strawberry juice, celery juice, carrot juice, cucumber juice, tomato juice) were evaluated. The linear ranges of the 350 pesticides were from 5 to 500 μg/kg, with good correlation coefficients greater than 0.990. The limits of detection (LODs) were 0.3-3.0 μg/kg and the limits of quantification (LOQs) were 1.0-10.0 μg/kg. The average recoveries at three spiked levels of 10, 100, 200 μg/kg were in the range of 72.8-122.4%, with relative standard deviations (RSDs) of 2.0-10.8%. The method has effectively improved the determination efficiency of pesticide residue screening by high-resolution mass spectrometry in vegetable and fruit juices.

Removal of Matrix Interferences by Nano-MgO and Co-Adsorbents for Accurate Multi-Pesticide Residue Analysis in the Chinese Medicinal Herb, Paeoniae Radix Alba

A simple, accurate, and high-throughput analytical method was developed to detect 123 pesticide residues in Chinese medicinal herb Paeoniae Radix Alba (PRA) by introducing nano-MgO as a highly efficient purification material based on quick, easy, cheap, effective, rugged, and safe (QuEChERS) design concept. Various PRA samples were extracted using 8 mL 0.5% acetic acid-acetonitrile solution and purified by a dispersive solid-phase extraction method with 30 mg nano-MgO, 40 mg primary secondary amine (PSA), and 40 mg octadecylsilane (C18) as the cleanup adsorbents, followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). 70.7% of pesticides showed a weak matrix effect after the purification process, indicating that this method can give the precise quantitative analysis of trace pesticides residue. The method was systematically validated under optimal conditions in five different kinds of PRA samples; good linearity was observed in the concentration range of 0.5-250 μg/L or 1-250 μg/L. Pesticide recovery in each sample spiked at concentrations of 20, 50, and 200 μg/kg ranged from 98.0% to 111% and the mean relative standard deviation ranged from 2.72% to 5.70%. Furthermore, the method comparison with the traditional QuEChERS method suggested the feasibility, advantages, and potential application prospect of the present method for the multi-pesticide residue analysis in various PRA samples.

Simultaneous determination of 114 pesticides in complex Chinese herbal medicine Fritillaria using ordered mesoporous carbon CMK-3 as a reversed-dispersive solid phase extraction sorbent

Fritillaria, a traditional Chinese herbal medicine, is classified into many medicinal species and contains numerous complex components. It is thus difficult to simultaneously detect multiple pesticide residues in different Fritillaria species. An easy, reliable, and widely applicable analytical method based on a modified Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) method coupled with LC-MS/MS was developed to solve these problems encountered during pesticide residue analysis in complex Fritillaria matrices. Ordered mesoporous carbon CMK-3 and a primary secondary amine (PSA) were used as efficient purification sorbents by optimization of the QuEChERS process. Systematic method validation was performed for four species of Fritillaria. The matrix effect of pesticides varied among different Fritillaria species, and matrix-matched standard solutions were thus employed for quantitative analysis. The mean recoveries of all pesticides ranged from 88.6% to 95.5%, with mean relative standard deviations (RSD) lower than 6% at spiked concentrations of 30, 120, and 240 μg kg⁻¹. The limits of quantification (LOQ) for the developed method were in the range of 30–120 μg kg⁻¹. This method was further used to analyze 47 Fritillaria samples from Zhejiang province, China, and seven pesticides were detected in 22 Fritillaria samples. These results demonstrate that the developed method is suitable for an accurate analysis of multiple pesticide residues in various Fritillaria.

Fritillaria, a traditional Chinese herbal medicine, is classified into many medicinal species and contains numerous complex components.

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.

Determination of 107 Pesticide Residues in Wolfberry with Acetate-buffered Salt Extraction and Sin-QuEChERS Nano Column Purification Coupled with Ultra Performance Liquid Chromatography Tandem Mass Spectrometry

A multi-residue method for the determination of 107 pesticide residues in wolfberry has been developed and validated. Similar pretreatment approaches were compared, and the linearity, matrix effect, analysis limits, precision, stability and accuracy were validated, which verifies the satisfactory performance of this new method. The LODs and LOQs were in the range of 0.14–1.91 µg/kg and 0.46–6.37 µg/kg, respectively. The recovery of analytes at three fortification levels (10 µg/kg, 50 µg/kg, 100 µg/kg) ranged from 63.3–123.0%, 72.0–118.6% and 67.0–118.3%, respectively, with relative standard deviations (RSDs) below 15.0%. The proposed method was applied to the analysis of fifty wolfberry samples collected from supermarkets, pharmacies and farmers’ markets in different cities of Shandong Province. One hundred percent of the samples analyzed included at least one pesticide, and a total of 26 pesticide residues was detected in fifty samples, which mainly were insecticides and bactericide. Several pesticides with higher detection rates were 96% for acetamiprid, 82% for imidacloprid, 54% for thiophanate-methyl, 50% for blasticidin-S, 42% for carbendazim, 42% for tebuconazole and 36% for difenoconazole in wolfberry samples. This study proved the adaptability of the developed method to the detection of multiple pesticide residues in wolfberry and provided basis for the research on the risks to wolfberry health.