Multiresidue method for determination of 88 pesticides in berry fruits using solid-phase extraction and gas chromatography–mass spectrometry: Determination of 88 pesticides in berries using SPE and GC–MS

Quantification of trace fenuron in waste water samples by matrix matching calibration strategy and gas chromatography-mass spectrometry after simultaneous derivatization and preconcentration

This study presents a highly sensitive and accurate analytical strategy for the determination of fenuron in wastewater samples using gas chromatography-mass spectrometry (GC-MS). Simultaneous derivatization and spray-based fine droplet formation-liquid phase microextraction (SFDF-LPME) method was developed and performed to achieve low detection limits. The parameters of the derivatization and SFDF-LPME method were optimized by univariate approach to improve sensitivity and selectivity. Under the optimum SFDF-LPME-GC-MS conditions, the limit of detection (LOD) and limit of quantitation (LOQ) were found to be 0.15 and 0.49 mg/kg, respectively. In addition, the linear range was calculated as 0.51-24.50 mg/kg. Recovery studies were carried out on wastewater samples to determine the accuracy of the developed method and its applicability to real sample matrix. Matrix matching calibration strategy was applied to eliminate/reduce any possible interference effects caused by the complexity of the wastewater matrix and to increase the accuracy of the analytical results. Percent recovery results varied between 85.9 and 120.9% with small percent relative standard deviation values. These results were satisfactory in terms of the accuracy and applicability of the proposed method for wastewater samples.

Pesticide Residues in Mandarins: Three-Year Monitoring Results

The demand of plant production product use has increased because of the current system of citrus production, which prioritizes high agricultural yields. Therefore, the monitoring of pesticide residues in citrus fruits and other agricultural products and their impacts on human health and food security are of great concern. This study aims to determine multi-class pesticides including highly polar residues in satsuma mandarins. A total of 226 mandarin samples were collected over three consecutive harvesting years from 2019 to 2021 in the Izmir region of Turkey. Targeted compounds included pesticides and metabolites with European Union (EU) regulatory levels, plus other non-approved residues and highly polar compounds. The residues excluding highly polar substances were analyzed by applying the quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction and liquid chromatography-triple quadrupole mass spectrometry (LC-MS/MS) determination for 434 analytes and gas chromatography-triple quadrupole mass spectrometry (GC-MS/MS) determination for 71 analytes. For six highly polar pesticides, sample preparation was based on Quick Polar Pesticides (QuPPe) extraction. The polar residues were determined by LC-MS/MS using internal standards. Forty different residues, including two highly polar substances, were recorded in mandarin samples through three harvesting years. In 8.4% of the samples, no quantifiable residues were detected, whereas 207 samples contained at least one residue. The maximum residue level (MRL) exceedances were recorded for 22.1% of the samples. The two most frequently found pesticides were phosphonic acid and spirotetramat, with an incidence rate of 48.7% and 46.5%, respectively. The concentration of phosphonic acid and spirotetramat in mandarin samples varied from 0.026 to 39.386 mg kg^-1 and from 0.010 to 1.485 mg kg^-1, respectively. The results will enable researchers and regulatory authorities to assess the extent of pesticide presence, identify potential risks, and take necessary measures to ensure the safety of satsuma mandarins for consumers.

Magnetic dispersive solid-phase extraction of some pesticides from fruit juices using monodisperse nanosorbent combined with dispersive liquid-liquid micro-extraction

In this study, the new synthesized magnetic nanoparticles based on amorphous carbon have been used as a sorbent in magnetic dispersive solid-phase extraction prior to dispersive liquid-liquid micro-extraction. The developed method was applied for analysis of ten pesticides from different fruit juice samples by gas chromatography-flame ionization detection. In this work, a few mg of the sorbent is added into an aqueous solution containing the analytes. Adsorption and desorption of the compounds of interest are accelerated by vortexing and sonication, respectively. To achieve high enrichment factors, a suitable organic solvent (iso-propanol) is used to elute the target analytes from the nanosorbent. The obtained iso-propanol is phased and 1,1,2-trichloroethane are employed as the disperser and extraction solvents, respectively, in the following micro-extraction procedure. The synthesized magnetic nanoparticles were characterized by scanning electron microscope, X-ray diffraction, vibrating sample magnetometer, and Fourier-transform infrared spectrophotometer. To achieve the high extraction efficiency and optimum conditions, all parameters that could affect the extraction yield were investigated. Under optimum conditions, the method had broad linear ranges with a proper linearity (r² ≥ 0.9987). Limits of detection and quantification for analysis of the selected pesticides were found in the ranges of 0.5-1.0 and 1.7-3.3 µg L^-1, respectively. High enrichment factors and extraction recoveries were obtained in the ranges of 321-438 and 64-88%, respectively. To evaluate repeatability of the method, it was performed on two sets of standard solutions at the concentrations of 10 and 50 µg L^-1 (each analyte). Relative standard deviations varied in the ranges of 2-6% and 4-7% for intra- (n = 6) and inter-day (n = 5) precisions, respectively.

Quantification of 363 Pesticides in Leafy Vegetables (Dill, Rocket and Parsley) in the Turkey Market by Using QuEChERS with LC-MS/MS and GC-MS/MS

Contamination of agricultural products with pesticide residues is a growing concern due to their adverse health effects and increasing worldwide usage of pesticides. In 2021 a total of 200 samples of green leafy vegetables, including 80 dill, 80 rocket and 40 parsley, purchased from greengrocer shops, markets and bazaars in Corum Province, Turkey, were monitored for pesticide residues. In green leafy vegetables, 363 pesticides were analyzed using a quick, easy, cheap, effective, rugged, and safe (QuEChERS) sample preparation, followed by liquid chromatography coupled to mass spectrometry (LC-MS/MS) for 311 residues and gas chromatography coupled to mass spectrometry (GC-MS/MS) for 52 residues. The method was in-house validated at two fortification levels, and satisfactory recoveries and precisions were achieved for all residues. No quantifiable residues were found in 35% of the samples, whereas 43 residues belonging to 24 different chemical classes were detected in 130 green leafy vegetables. Among the green leafy vegetables, the highest occurrence frequency was recorded in the rocket, followed by dill and parsley. In 46% of the green leafy vegetables, the residue levels exceeded European Union Maximum Residue Levels (EU MRLs). The most frequently detected pesticides were pendimethalin (22.5%), diuron (38.7%) and pymetrozine (52.5%) in dill, rocket and parsley, respectively.

Extraction and quantification of pesticides and metals in palm wines by HS-SPME/GC-MS and ICP-AES/MS

In this study, HS-SPME/GC-MS and ICP-AES/MS methods are presented to extract and quantify pesticides and metals in palm wines. Various parameters affecting the extraction were investigated: SPME fiber, equilibrium and extraction time, extraction temperature, salinity, and stirring, through an experimental design with 45 trials. The developed method allowed to identify 35 pesticides and quantify 29 of them, from different families of pesticides in 32 palm wine samples. Method performance was evaluated in terms of linearity, repeatability, LOD, LOQ, and accuracy. Among the 32 samples analyzed in 3 replicates, 7 pesticides were detected in 10 samples. Dichlorvos was the only pesticide detected at levels above the European maximal limits. Additionally, 10 of the 19 metals explored by ICP-AES and ICP-MS were found in all samples. Six metals were detected in different samples at levels above the European or OIV maximal limits for drinking water or wine.

A review of the modern principles and applications of solid-phase extraction techniques in chromatographic analysis

Analytical processes involving sample preparation, separation, and quantifying analytes in complex mixtures are indispensable in modern-day analysis. Each step is crucial to enriching correct and informative results. Therefore, sample preparation is the critical factor that determines both the accuracy and the time consumption of a sample analysis process. Recently, several promising sample preparation approaches have been made available with environmentally friendly technologies with high performance. As a result of its many advantages, solid-phase extraction (SPE) is practiced in many different fields in addition to the traditional methods. The SPE is an alternative method to liquid–liquid extraction (LLE), which eliminates several disadvantages, including many organic solvents, a lengthy operation time and numerous steps, potential sources of error, and high costs. SPE advanced sorbent technology reorients with various functions depending on the structure of extraction sorbents, including reversed-phase, normal-phase, cation exchange, anion exchange, and mixed-mode. In addition, the commercial SPE systems are disposable. Still, with the continual developments, the restricted access materials (RAM) and molecular imprinted polymers (MIP) are fabricated to be active reusable extraction cartridges. This review will discuss all the theoretical and practical principles of the SPE techniques, focusing on packing materials, different forms, and performing factors in recent and future advances. The information about novel methodological and instrumental solutions in relation to different variants of SPE techniques, solid-phase microextraction (SPME), in-tube solid-phase microextraction (IT-SPME), and magnetic solid-phase extraction (MSPE) is presented. The integration of SPE with analytical chromatographic techniques such as LC and GC is also indicated. Furthermore, the applications of these techniques are discussed in detail along with their advantages in analyzing pharmaceuticals, biological samples, natural compounds, pesticides, and environmental pollutants, as well as foods and beverages.

Development of a new and facile method for determination of chlorpyrifos residues in green tea by dispersive liquid-liquid microextraction

In this work a simple, rapid, and environmentally friendly method has been established for the determination of chlorpyrifos residue in green tea by dispersive liquid-liquid microextraction and gas chromatography-flame photometric detection. Some experimental parameters that influence extraction efficiency, such as the kind and volume of disperser solvents and extraction solvents, extraction time, addition of salt and pH, were investigated. And the optimal experimental conditions were obtained, quantitative analysis was carried out using external standard method. The correlation coefficient of the calibration curves was 0.999 with in 0.05 mg/kg to 5 mg/kg. The results showed that under the optimum conditions, the enrichment factors of the chlorpyrifos was about 554.51, the recoveries for standard addition fell in the range from 91.94 to 104.70% and the relative standard deviations was 4.61%. The limit of quantification of chlorpyrifos in green tea was 0.02 μg/mL at the signal/noise ratio of 3.

Optimization of an Analytical Method for Indoxacarb Residues in Fourteen Medicinal Herbs Using GC–μECD, GC–MS/MS and LC–MS/MS

Pesticide residue analysis in medicinal herbs is a challenging task because of the matrix effect and its influence on quantitative analysis despite the continuous development of several new analytical methods and instrumentations. In this study, a modified QuEChERS method was developed for the analysis of indoxacarb residue in medicinal herbs by using the conventional instrument, gas chromatography micro-electron-capture-detector (GC–μECD), and comparing it with gas chromatography–tandem mass spectrometry (GC–MS/MS) and liquid chromatography–tandem mass spectrometry (LC–MS/MS). Samples were extracted with acetonitrile and purified using an NH2 cartridge. The optimized method efficiently removes the co-extractives and offered a limit of quantification of 0.01 mg kg−1. The GC–μECD analysis results of indoxacarb in seven medicinal herbs out of fourteen species at a fortification level of 0.01 mg kg−1 showed a recovery range of 79.7–117.6%, while the rest showed recovery > 120%. Similarly, the recovery of indoxacarb by GC and LC–MS/SM were 74.1–105.9 and 73.0–99.0%, respectively, with a relative standard deviation of <20%. Matrix effects for the majority of medicinal herbs analyzed by GC–MS/MS were >±20%. Whereas the results for LC–MS/MS were <20%, which was within the acceptable range according to the SANTE/11312/2021 guidelines. Considering the performance of the method and alignment with the regulatory guidelines, LC–MS/MS is recommended for the analysis of indoxacarb in selected medicinal herbs.

Advancement and New Trends in Analysis of Pesticide Residues in Food: A Comprehensive Review

Food safety is a rising challenge worldwide due to the expanding population and the need to produce food to feed the growing population. At the same time, pesticide residues found in high concentrations in fresh agriculture pose a significant threat to food safety. Presently, crop output is being increased by applying herbicides, fungicides, insecticides, pesticides, fertilizers, nematicides, and soil amendments. A combination of factors, including bioaccumulation, widespread usage, selective toxicity, and stability, make pesticides among the most toxic compounds polluting the environment. They are especially harmful in vegetables and fruits because people are exposed to them. Thus, it is critical to monitor pesticide levels in fruits and vegetables using all analytical techniques available. Any evaluation of the condition of pesticide contamination in fruits and vegetables necessitates knowledge of maximum residue levels (MRLs). We set out the problems in determining various types of pesticides in vegetables and fruits, including the complexity and the diversity of matrices in biological materials. This review examines the different analytical techniques to determine the target analytes that must be isolated before final consumption. Many processes involved determining pesticide residues in fruits and vegetables and their advantages and disadvantages have been discussed with recommendations. Furthermore, MRLs of target pesticide residues in fruit and vegetable samples are discussed in the context of data from the literature. The review also examines MRLs' impact on the international trade of fruits and vegetables. Accurate, sensitive, and robust analytical procedures are critical to ensuring that pesticide levels in food products are effectively regulated. Despite advances in detection technology, effective sample preparation procedures for pesticide residue measurement in cereals and feedstuffs are still needed. In addition, these methods must be compatible with current analytical techniques. Multi-residue approaches that cover a wide range of pesticides are desired, even though pesticides' diverse natures, classes, and physio-chemical characteristics make such methods challenging to assemble. This review will be valuable to food analysts and regulatory authorities to monitor the quality and safety of fresh food products.

Integrated QuEChERS strategy for high-throughput multi-pesticide residues analysis of vegetables

An integrated QuEChERS strategy was developed by combining the extraction and purification processes into a single step. All of the pretreatment procedures could be performed in one tube within 5 min with the aid of magnetic nanoparticles and careful optimization of the key parameters, including the dosages of the sorbents (magnetic nanoparticles, C18, and graphitized carbon black), dehydrating and salting out reagents. The optimal method was validated and compared with the conventional QuEChERS method, demonstrating its clear superiority in terms of operating procedure, sample pretreatment time, and reagent dosages while affording equivalent pesticide recoveries and matrix effects. Further application of this method was performed to analyze 127 pesticide residues in solanaceous vegetables (tomato, pepper, and eggplant), leafy vegetables (brassica campestris and cabbage), legumes (green beans and cowpea), melon-type vegetables (cucumber and towel gourd), and a root vegetable (water bamboo), with the mean recoveries of the pesticides in the individual vegetable samples ranging from 70.6 to 92.8%. The method LOQs for these pesticides ranged from 10 to 50 μg/kg depending on the matrix. These results fully confirmed its wide applicability and versatility for achieving robust, rapid, and high-throughput multi-pesticide residues analysis in vegetable samples. More importantly, the developed strategy provides a greener and more "QuEChERS" design concept, which could be applied to the analysis of numerous types of pesticide residues in various matrices.

Polychlorinated Diphenyl Sulfides: An Emerging Class of Persistent, Bioaccumulative, and Toxic Substances in the Environment

Polychlorinated diphenyl sulfides (PCDPSs) have recently attracted increasing attention due to their potential adverse effects on human and ecosystem health. We present a review regarding their environmental occurrence, persistence, bioaccumulation, toxicity, and biotransformation. The existing literature demonstrates that PCDPSs are ubiquitous in various environmental matrices, are persistent in the environment, and have long-range transport potential. In addition, the high bioaccumulation potential of these emerging pollutants, especially the low chlorinated PCDPS congeners, has been confirmed based on both theoretical calculations and experimental investigations. Moreover, a spectrum of adverse effects, such as acute liver injury, retardation of development, reproductive disorders, and increased mortality have been widely reported in vertebrates. These adverse outcomes were associated with oxidative stress and activation of aryl hydrocarbon receptors. Given these findings, PCDPSs represent candidate persistent, bioaccumulative, and toxic substances and thus deserve further research to fully elucidate their environmental behavior and fate, and evaluate the risks to human and ecosystem health. Environ Toxicol Chem 2021;40:2657-2666. © 2021 SETAC.

Development of a method based on dispersive liquid-liquid microextraction followed by partial vaporization of the extract for ultra-preconcentration of some pesticide residues in fruit juices

A new simple and efficient method has been developed for the ultra-preconcentration of multiclass pesticide residues including penconazole, chlorpyrifos, ametryn, clodinafop-propargyl, diniconazole, oxadiazon, and fenpropathrin from some fruit juice samples based on evaporation of the sedimented organic phase obtained from dispersive liquid-liquid microextraction. The enriched target analytes were analyzed by gas chromatography-flame ionization detection. In the microextraction procedure, a mixture of iso-propanol as a disperser and 1,2-dibromoethane as an extraction solvent is quickly injected into an aqueous phase containing the analytes and centrifuged. Afterward, the sedimented phase is transferred into a special shaped vaporization vessel and vaporized with nitrogen gas stream until remaining about 2 µL of it. Eventually, 1 µL of the remained sedimented phase is removed and analyzed by separation system. The optimum extraction and disperser solvents were found to be 1,2-dibromoethane and iso-propanol, respectively. In addition, the optimum pH range was 6-8, and nitrogen gas stream at a flow rate of 90 mL min^-1 in a downward oriented vessel was applied. Eventually, the limits of detection and quantification were obtained in the ranges of 45-78 and 149-261 ng L^-1, respectively. Relative standard deviations at the concentrations of 300, 500 and 1000 ng L^-1 of each analyte were ranged between 2.2% and 5.8% for intra-day (n = 6) precision. Inter-day (n = 3) precision at a concentration of 500 ng L^-1 of each analyte was obtained in the range of 4.9-7.1%. In addition, enrichment factors and extraction recoveries were ranged from 1382-2246 and 55-89%, respectively. Finally, the method was successfully utilized in analysis of the target pesticides in the selected juices.

Multiclass Pesticide Residue Analysis in Fruit and Vegetable Samples by Combining Acetone-Based Salting-Out Assisted Extraction with Dispersive Liquid-Liquid Microextraction

Isolation and enrichment of multiclass pesticides’ residue, namely, fungicides (benalaxyl), herbicides (atrazine), carbamate insecticides (carbofuran), organophosphate insecticides (chlorpyrifos), organochlorine insecticides (4,4′-DDT), and pyrethroid insecticides (bifenthrin), were made by combining acetone-based salting-out assisted extraction with the dispersive liquid-liquid microextraction (SADLLME) method, followed by high-performance liquid chromatography-diode array detection (HPLC-DAD). The effect of the type and volume of the extraction solvent in the pretreatment step, the volume of the disperser solvent (acetone extract), the type and volume of the extraction solvent, pH, and salt addition in the DLLME procedure was studied. Good coefficient of determination (R2 ≥ 0.9964) was obtained for all the target analytes. The limits of detection and quantification limits were between 2.1 and 4.5 and 5.7 and 12.9 µg/kg, respectively, with adequate enrichment factors ranging from 37.6 to 191. The recoveries of spiked blank tomato ranged from 86.8 to 109.5%. The limit of quantification of the proposed method was lower than the maximum residue limits set by the European Union. The repeatability and reproducibility of precisions ranged between 2.9 and 8.0 and 4.9 and 9.5%, respectively. The optimized and validated method was applied to quantify pesticides in tomato, pear, apple, and melon obtained from different markets. However, all target compounds studied in this work were not detected in any real samples applied. Overall, the work results revealed that the proposed method is useful for the sample extraction and preconcentration of the target analytes from fruits and vegetables.

Optimization and application of QuEChERS and SPE methods followed by LC-PDA for the determination of triazines residues in fruits and vegetables from Pietermaritzburg local supermarkets

QuEChERS and solid phase extraction (SPE) methods were optimized and applied for the extraction of triazines in fruit and vegetables. These extraction methods are easy, effective, rugged and safe. Also, they have the ability to purify the extracts which leads to lower detection limits and higher recoveries of the analytes. The analysis were conducted using liquid chromatography coupled to photodiode array detector. The limits of detection and quantification ranged from 0.4 -1.4 µg/kg and 1.5 - 4.5 µg/kg, respectively, for QuEChERS and 0.3 - 1.8 µg/kg and 1.4 - 4.9 µg/kg respectively, for SPE. The recoveries ranged from 84 to 102% for QuEChERS and 76-119% for SPE, with relative standard deviation less than 20% for both methods. The fruits and vegetables analysed were apples, pears, carrots, potatoes, tomatoes, avocado, cucumber, spinach, bananas, and oranges. The concentrations detected ranged between 6 and 46 µg/kg in fruits and 4 - 84 µg/kg in vegetables. Simazine was detected in all fruits and vegetable samples except in pear, while terbutylazine was not detected in all samples analysed. Propazine and ametryn were only found in carrot while pear sample only had atrazine. The proposed methods proved to be sensitive and accurate indicating their applicability for detection and monitoring of the selected triazines in fruits and vegetables. However, QuEChERS can be recommended for routine analysis of these triazines due to its fewer extraction steps compared to SPE which is important for turn-around time.

Effects of common inorganic anions on the ozonation of polychlorinated diphenyl sulfides on silica gel: Kinetics, mechanisms, and theoretical calculations

In this work, the ozonation properties of 2,2',3',4,5-pentachlorodiphenyl sulfide (PeCDPS) was systematically studied, with special emphasis on the underlying mechanism for the effects of inorganic ions. Kinetic experiments show that common ions can significantly reduce the oxidative properties of ozone, except for SO₃^2- and Cu²⁺. The inhibition effect of anions has been explained through the scavenging effect of free radicals and the generation of other free radicals with weaker oxidation potentials, but no research has reported on the effect of free radicals generated by anions on the degradation pathway. However, SO₃^2- and Cu²⁺ exerted a promoting effect through enhanced formation of ·OH via the hydrolysis effect and the catalyzed decomposition of O₃, respectively. According to the intermediate products identified by high performance liquid chromatography-mass spectrometry/mass spectrometry (HPLC-MS/MS) analysis, direct oxidation of S atom, substitution of Cl atom with -OH group, and hydroxylation of the benzene ring were commonly observed. The addition of NO₂^- and SO₃^2- produced new free radicals like ·NO₂, ·SO₃ and ·SO₄^-, which would attack the parent compound or its primary product, thus influencing the degradation efficiency and pathways. The radicals initiated reactions and the structures of the corresponding products were further rationalized by density functional theory (DFT) calculations. These findings provide new insights into the effects of common anions on ozone oxidation of organic compounds.

Determination of fipronil and bixafen pesticides residues using gas chromatography mass spectroscopy with matrix matching calibration strategy after binary dispersive liquid-liquid microextraction

The objective of this study was to determine bixafen and fipronil residues in domestic and industrial wastewater, soil and mint samples by binary dispersive liquid-liquid microextraction method (BDLLME) prior to gas chromatography-mass spectrometry (GC-MS). Extraction efficiency for the selected analytes was improved by optimizing the parameters such as solvent type, ratio and volume, dispersive solvent type/volume, mixing type and duration to increase overall analytical performance. Under the optimum chromatographic and extraction conditions, limits of detection values for bixafen and fipronil were determined as 7.3 and 6.1 µg L^-1, respectively. Spiking experiments were performed for domestic and industrial wastewater, soil and mint samples to evaluate applicability and accuracy of the proposed method. Recovery results for the samples were calculated in the range of 89.4%-112.6% via matrix matching calibration strategy. It was determined that the detection power of GC-MS system was improved 7.8 times for bixafen and 119 times for fipronil over LOD comparisons of conventional GC-MS and B-DLLME-GC-MS systems.

In vitro assessment of pesticide residues bioaccessibility in conventionally grown blueberries as affected by complex food matrix

The aim of this study was to investigate the bioaccessibility of pesticide residues in blueberries (commercial and sample from controlled field trial) from Serbia, involving the presence of a complex food matrix and to assess the potential risk to human health. The presence of nine active substances (azoxystrobin, boscalid, fludioxonil, cyprodinil, pyrimethanil, pyridaben, pyriproxyfen, acetamiprid and thiametoxam) in initial blueberry samples was determined in concentration range from 5.15 μg/kg for thiametoxam to 187 μg/kg for azoxystrobin. Clothianidin, metabolite of thiametoxam, was not detected in any blueberry sample. However, after in vitro digestion, the content of initially detected pesticides residues was significantly decreased or it was below limit of quantification resulting in the total bioaccessibility of about 15%. Azoxystrobin, pyrimethanil and fludioxonil was quantified in digestive juice at concentrations which were about 81%, 37% and 10% less than the inital concentration, respectively. The presence of food matrix during digestion of blueberries even more severely reduced concentration of pesticide residues (total bioaccessibility was about 7%) compared to digestion without the food matrix. Only azoxystrobin was quantified after digestion with food matrix in concentration of 27 μg/kg in sample from controlled field trial and detected in two commercial samples but below the limit of quantification. Furthermore, chronic risk assessment indicated that risk is acceptable for the health of different human subpopulation groups. The current study on pesticides residues, most commonly applied on blueberries, provides for the first time an insight into their bioaccessibility under conditions that mimic physiological environment of human digestive tract.

Determination of 66 pesticide residues in livestock products using QuEChERS and GC-MS/MS

Determinations of 66 pesticide residues in different matrices including beef, pork, chicken, eggs, and milk were conducted using GC-MS/MS combined with the quick easy cheap effective rugged safe (QuEChERS) method for sample extraction. A high linearity was achieved in the concentration range from 2.5 to 1000 µg/L (R ² ≥ 0.99), and the limit of quantification for multi-class pesticides ranged from 0.74 to 23.1 µg/kg. The recovery ranged from 70.0 to 120%, while the reproducibility of the measurements was between 0.23 and 19.9%. Monitoring was conducted for livestock products purchased from local markets. Chlorpyrifos and fenitrothion in beef and chlorpyrifos in pork were detected below the maximum residue limits for the respective samples. No detectable residues were found in the other samples. Due to its high efficiency, reproducibility, and simple analytical operation, the proposed method can be applied to the regular monitoring of multi-residue pesticides in livestock products.

Trace analysis of organophosphorus pesticide residues in fruit juices and vegetables by an electrochemically fabricated solid-phase microextraction fiber coated with a layer-by-layer graphenized graphite/graphene oxide/polyaniline nanocomposite

Herein, a solid-phase microextraction pencil lead fiber coated with a layer-by-layer graphenized graphite/graphene oxide/polyaniline nanocomposite (GG/GO/PANI) was fabricated by an in situ electrochemical technique for the trace analysis of organophosphorus pesticide residues in packed grape and apple juice and also fresh tomato samples. The effects of various parameters, including the type of desorption solvent, adsorption time, desorption time, pH, salt addition, and stirring rate, on the extraction efficiency of the studied pesticides were investigated and accordingly, these parameters were optimized. The proposed fiber demonstrated desirable linear ranges (0.01-300 μg L-1) with good correlation coefficients (R2 ≥ 0.996) as well as low limits of detection (0.003-0.03 μg L-1) for the studied pesticides. The relative standard deviations (n = 5) for the extraction of 50 μg L-1 of each analyte were less than 7 and 11.5% for inter and intra-day precisions, respectively. This fast, facile, and repeatable electrochemical fabrication method produced a porous and homogeneous coating. The proposed fiber demonstrated good extraction efficiency, high stability, and long life-time despite being low cost. The successful application of the proposed fiber for the trace determination of pesticides in complex food matrices was proven by the satisfactory relative recoveries of 80.7-116.5%.

Enhancing levoglucosan production from waste biomass pyrolysis by Fenton pretreatment

Levoglucosan is served as a significant versatile product to generate high value-added chemicals and pharmaceutical additives. Levoglucosan was predominately produced from pyrolysate of cellulose. However, the direct fast pyrolysis of waste biomass produces a small quantity of levoglucosan in comparison with the theoretical value of cellulose. This study explored Fenton pretreatment as a possible route to enhance levoglucosan yield during the fast pyrolysis of the waste corncob. The experimental results showed that different Fenton pretreated conditions and pyrolytic temperatures played vital roles in the formation of levoglucosan. The levoglucosan yield from fast pyrolysis at 500 °C of corncob pretreated by Fenton reaction of 14 mL/g H₂O₂ and 16 mM FeSO₄ was about 95% higher than that of the untreated corncob. Additionally, Fenton pretreated corncob was capable of obtaining the levoglucosan at a low pyrolytic temperature (300 °C). It was mainly attributed to the effective disrupting of biomass structures and the selective degradation of lignin and hemicellulose during pretreatment. Furthermore, the powerful removal of alkali and alkaline earth metals during Fenton pretreatment was beneficial to increasing the levoglucosan yield. These findings demonstrate that Fenton pretreatment can provide a novel effective method to enhance levoglucosan yield during biomass fast pyrolysis.

High-throughput simultaneous analysis of multiple pesticides in grain, fruit, and vegetables by GC-MS/MS

A multi-component quantitative GC-MS/MS method for monitoring and inspecting agricultural products was developed for the simultaneous determination of 365 pesticide residues in grain, beans, fruit and vegetables. Twenty-six pesticides that have been authorised in foreign countries but not in Korea were included in the newly adapted Korean positive list system. The method was validated by analysing spiked samples at three concentrations (0.01, 0.05, and 0.1 mg/kg) for brown rice, soy beans, mandarin orange, potato and green pepper matrice, which represented grain, beans, fruit, and vegetables. More than 95% of 365 compounds satisfied the validation criteria of 70-120% recovery and ≤20% relative standard deviation obtained through the proposed simultaneous multi-component analysis. Twenty-two types of pesticides were detected in 76 food samples, whose concentrations were below the maximum residue limits. Among the newly added pesticides, lambda-cyhalothrin, an analogue of cyhalothrin, was detected in peaches. The method can be applied to the analysis and inspection of pesticide residues in domestic and imported agricultural products for safety control.

A Novel CdSe/ZnS Quantum Dots Fluorescence Assay Based on Molecularly Imprinted Sensitive Membranes for Determination of Triazophos Residues in Cabbage and Apple

In the present study we have developed a direct competitive CdSe/ZnS quantum dot (QD) fluorescence assay based on micro-array-imprinted membranes for the determination of triazophos in cabbage and apple. The imprinted membranes were directly synthesized on the surface of a 96-well plate by thermal polymerization using triadimefon as the dummy template. Under optimal conditions, the assay showed an excellent linear response over the concentration ranges of 0.1-10,000 μg L-1 with a good coefficient of determination (R 2= 0.982). The sensitivity (IC50) and limit of detection (LOD, expressed as IC15) of the developed assay were 3.63 mg L-1 and 0.31 μg L-1, respectively. The applicability of the developed approach was tested for detecting triazophos in incurred samples. The method showed excellent recoveries (109.6-118.9%) and relative standard deviations (RSDs) between 9.9 and 19.5%. The obtained results correlated well with those obtained by LC-MS/MS (R 2= 0.9995). The competitive assay using CdSe/ZnS QDs as fluorescence-labeled probe showed good sensitivity, steady and fast response, and excellent anti-interference ability compared to conventional fluorescence-quenching methods. Finally, the feasibility of the proposed methodology was successfully applied for detection of triazophos in real samples.

Analysis of pesticide residues in commercially available chenpi using a modified QuEChERS method and GC-MS/MS determination

To ensure the safety of the commercially available chenpi, a convenient and fast analytical method was developed for the determination of 133 pesticide residues in chenpi using gas chromatography-tandem mass spectrometry (GC-MS/MS). In this study, different extraction solvents, redissolution solvents and adsorbents were tested according to the recovery and purification effect to obtain a modified QuEChERS method. The samples were extracted with acetonitrile. During the clean-up step, octadecyl-modified silica (C18) and graphitized carbon black (GCB) were selected, and aminopropyl (NH₂) was used instead of primary secondary amine (PSA) because of its weaker ion exchange capacity which had little effect on the recovery of ditalimfos. Samples were quantified by matrix-matched calibration with internal standards. All pesticides showed good linearity in the respective range, both with values of r² > 0.99. The average recoveries of the pesticides spiked samples ranged from 70.0% to 112.2% with the RSDs of 0.2%–14.4%. The modified QuEChERS method was validated and applied to twenty real samples. Five pesticides were found in eight batches, but no pesticide exceeded the maximum residue limits (MRL, MRL reference to European commission).

Down-Regulation of hspb9 and hspb11 Contributes to Wavy Notochord in Zebrafish Embryos Following Exposure to Polychlorinated Diphenylsulfides

It is hypothesized that key genes, other than ahr2, are present and associated with the development of a unique type of notochord malformation known as wavy notochord in early life stages of zebrafish following exposure to polychlorinated diphenylsulfides (PCDPSs). To investigate the potential mechanism(s), time-dependent developmental morphologies of zebrafish embryos following exposure to 2500 nM 2,4,4',5-tetra-CDPS, 2,2',4-tri-CDPS or 4,4'-di-CDPS were observed to determine the developmental time point when notochord twists began to occur (i.e., 21 h-postfertilization (hpf)). Simultaneously, morphometric measurements suggested that PCDPS exposure did not affect notochord growth at 21 or 120 hpf; however, elongation of the body axis was significantly inhibited at 120 hpf. Transcriptome analysis revealed that the retardation of body growth was potentially related with dysregulation of transcripts predominantly associated with the insulin-associated Irs-Akt-FoxO cascade. Moreover, knockdown and gain-of-function experiments in vivo on codifferentially expressed genes demonstrated that reduced expression of hspb9 and hspb11 contributed to the occurrence of wavy notochord. The results of this study strongly support the hypothesis that the notochord kinks and twists are triggered by the down-regulation of hspb9 and hspb11, and intensified by body growth retardation along with normal notochord length in PCDPS-exposed zebrafish embryos.

Simultaneous Determination of Pesticides in Fruits by Using Second-Order Fluorescence Data Resolved by Unfolded Partial Least-Squares Coupled to Residual Bilinearization

In the present work, a chemometric-assisted spectrofluorimetric method has been developed for the simultaneous determination of natural fluorescent pesticides, carbaryl, carbendazim, and thiabendazole, in orange and banana. Only a simple extraction with methanol was required as sample pretreatment. Emission-excitation fluorescence matrices were obtained and resolved by using a second-order multivariate calibration method based on unfolded partial least-squares combined with residual bilinearization (U-PLS/RBL) for achieving “second-order advantage.” In this way, pesticides were determined in fruits even in the presence of inner filter effects, background interactions, strong spectral overlapping, and unexpected components. U-PLS can cope with effects that cause trilinearity loss such as, inner filter effects, including background in the calibration set; meanwhile, RBL allows to resolve the presence of unexpected components. The extraction technique was validated against a commonly applied technique based on the use of ethyl acetate and sodium sulfate. Besides, results obtained for real samples were statistically compared with those obtained by using HPLC. LODs of 0.038, 0.054, and 0.018 mg·kg−1 and 0.044, 0.072, and 0.020 mg·kg−1 were obtained for carbaryl, carbendazim, and thiabendazole in banana and orange samples, respectively; values were in accordance with the MRLs (Maximum Residue Limits) established by different official control organizations such as National Food Safety and Quality Service (SENASA), Codex Alimentarius (based on Food and Agriculture Organization (FAO) of the United Nations and World Health Organization (WHO), and Environmental Protection Agency (EPA).

Analytical method validation for terbutryn using gas chromatography/ion trap, gas chromatography/mass selective detector, and liquid chromatography/triple quadrupole mass spectrometers

Analytical methods including solvent extraction followed by gas chromatography/ion-trap (GC/IT) with scan and MS/MS mode, a GC/mass selective detector (GC/MSD), and liquid chromatography/triple quadrupole mass spectrometers (LC/MS/MS) were optimized to identify and quantify terbutryn. The spike recovery was 96.5% using GC/IT with scan mode and 103.5% with MS/MS mode, 90.3% by GC/MSD, and 92.5% by LC/MS/MS. The limit of detection (LOD) was 0.0015 mg/kg by GC/IT with scan, 0.026 mg/kg with MS/MS mode, 0.015 mg/kg with GC/MSD, and 0.026 mg/kg by LC/MS/MS. Of the four methods, GC/IT with scan mode was determined to be the most sensitive (with LOD: 0.0015 mg/kg and limit of quantitation (LOQ): 0.0047 mg/kg), rapid (retention time: 9.6 min) and the most precise method (relative standard deviation: 17%) for the quantification of terbutryn. GC/IT with scan mode proved to be the more sensitive analytical method for terbutryn than other methods in this study, showing better accuracy and rapid analysis.

Novel magnetic hollow zein nanoparticles for preconcentration of chlorpyrifos from water and soil samples prior to analysis via high-performance liquid chromatography (HPLC)

Herein, magnetically hollow zein nanoparticles were synthesized and used as a magnetic sorbent for the preconcentration of chlorpyrifos and its analysis by high-performance liquid chromatography (HPLC). Morphology of the sorbent was characterized by transmission electron microscopy (TEM). In this study, the effects of important parameters such as pH of the solution, adsorption and desorption time, type and volume of desorption solvent, and salt addition were investigated. Under optimized experimental conditions, the linear range was from 50 to 2000 μg mL-1, and an LOD of 25 μg L-1 was calculated. The relative standard deviations (RSD) varied from 3.8 to 5.1% (n = 5). The enrichment factors for 50 and 100 μg L-1 samples were calculated as 187 and 210, respectively. The developed method was successfully applied in soil and water samples and showed good extraction recoveries.

An optimized band-target entropy minimization for mass spectral reconstruction of severely co-eluting and trace-level components

Gas chromatography-mass spectrometry (GC-MS) is a versatile analytical method but its data is usually complicated by the presence of severely co-eluting and trace-level components. In this work, we introduce an optimized band-target entropy minimization approach for the analysis of complex mass spectral data. This new approach enables an automated mass spectral analysis which does not require any user-dependent inputs. Moreover, the approach provides improved sensitivity and accuracy for mass spectral reconstruction of severely co-eluting and trace-level components. The accuracy of our approach is compared to the automatic mass spectral deconvolution and identification system (AMDIS) with two controlled mixtures and a sample of Eucalyptus essential oil. Our approach was able to putatively identify 130 compounds in Eucalyptus essential oil, which was 46% in excess of that identified by AMDIS. This new approach is expected to benefit GC-MS analysis of complex mixtures such as biological samples and essential oils, in which the data are often complicated by co-eluting and trace-level components. Graphical abstract ᅟ.

An efficient cleanup method coupled with gas chromatography and mass spectrometry for multi-pesticides residue analysis in complex plant matrices

We aimed to develop an efficient cleanup method for multi-pesticides residue analysis in complex plant matrices, shallot, ginger, garlic, onion, leek, and celery. Column chromatography was used as the cleanup method and fabricated with florisil and graphitized carbon black as the adsorbents. The amount of the graphitized carbon black adsorbent and the choice of the elution solvent were systematically investigated for exploring the best combination. The target pesticides covered organochlorine, pyrethroid, and organophosphorus pesticides, and were 38 in total. The method validation and comparison were performed to verify its feasibility and advantages in operation convenience and purification efficiency. The method limit of quantitation varied from 0.01 to 0.03 mg/kg, which depends on the pesticides and the sample matrices. The recoveries of the pesticides ranged from 60.5 to 128% (RSD ≤ 19.0%) at the spiked concentration level of 0.01 (or 0.03) mg/kg and 62.9 to 130% (RSD ≤ 13.0%) at 0.1 mg/kg. Compared with the commercial cleanup solid-phase extraction cartridges, the present adsorbent combination displayed better purification effect and shorter sample pretreatment time, demonstrating potential application prospect in the complex matrix sample analysis.