A multi-residue method for pesticide residue analysis in rice grains using matrix solid-phase dispersion extraction and high-performance liquid chromatography–diode array detection

The fate and potential hazards of chlorfenapyr and one metabolite tralopyril in cabbages: A comprehensive investigation

The potential hazards of chlorfenapyr warrant attention owing to its widespread application on vegetables. A comprehensive investigation of the fate of chlorfenapyr in the ecosystem is imperative. This paper presents a method for detecting chlorfenapyr and tralopyril in cabbages, which exhibits good linearity (determination coefficients > 0.99) and satisfactory recoveries (82.50 %-108.03 %). Chlorfenapyr residues in cabbages demonstrate a positive correlation with its application dose and time. Tralopyril can inhibit the dissipation of chlorfenapyr, as evidenced by the half-lives of 5.67-11.14 d (chlorfenapyr) and 6.91-14.77 d (total chlorfenapyr). The results of terminal residues (<2.0 mg/kg) and dietary risk assessment (<100 %) suggest preharvest intervals of 14 d (greenhouse) and 10 d (open-field). Additionally, the uptake of chlorfenapyr in cabbages is limited (translocation factor < 1), while the downward translocation predominantly occurs through phloem transport. The findings provide valuable insights for understanding the fate and potential risks of chlorfenapyr in cabbages.

Technology for Rapid Detection of Cyromazine Residues in Fruits and Vegetables: Molecularly Imprinted Electrochemical Sensors

Cyromazine is an insect growth regulator insecticide with high selectivity and is widely used in the production and cultivation of fruits and vegetables. In recent years, incidents of excessive cyromazine residues in food have occurred frequently, and it is urgent to establish an accurate, fast, and convenient method for the detection of cyromazine residues to ensure the safety of edible agricultural products. To achieve rapid detection of cyromazine residues, we prepared a molecularly imprinted electrochemical sensor for the detection of cyromazine residues in agricultural products. Samples of tomato (Lycopersicon esculentum Miller), cowpea (Vigna unguiculata), and water were tested for the recovery rate of cyromazine. The results showed that the concentration of cyromazine showed a good linear relationship with the peak response current of the sensor developed in this study. The lower limit of detection for cyromazine was 0.5 µmol/L, and the sensor also had good reproducibility and interference resistance. This paper can be used as a basis for the study of methods for the detection of cyromazine residues in edible agricultural products.

Development, Validation and Application of an Ultra-High-Performance Liquid Chromatography-Tandem Mass Spectrometry (UHPLC-MS/MS) Method after QuEChERS Cleanup for Selected Dichloroanilines and Phthalates in Rice Samples

Dichloroanilines and phthalic acid esters (phthalates) are food contaminants, stable in solution even at high temperatures, which exhibit considerable toxic effects, while acting as endocrine disruptors. In the present study, a quick and easy UHPLC-MS/MS method for simultaneously analyzing two dichloroanilines (3,4-DCA and 3,5-DCA) and six phthalates (DMP, DnBP, BBP, DnOP, DEHP, and mBP) in commercial rice samples was developed, validated, and applied. For the cleanup process, the methodology of quick, easy, cheap, effective, rugged, and safe (QuEChERS) was applied, whereas different dispersants (GCB, C18, and PSA) were tested. What was developed and presented had limits of detection ranging from 0.017 up to 0.12 mg/kg, recoveries (trueness) below 120%, and relative standard deviations (RSD; precision) <15% for all target analytes, whilst no significant matrix effects occurred for all analytes. It was determined that the rice samples analyzed using this developed technique did not contain any of the two dichloroaniline compounds (3,4-DCA and 3,5-DCA) nor two of the six phthalate (DMP and mBP) compounds analyzed, while the levels of other phthalates (DEHP, BBP, DnBP and DnOP) were within the legal limits. The current method ensures a fast and easy approach for the high-throughput quantification of the selected food contaminants in rice.

Simultaneous Determination of Pyridate, Quizalofop-ethyl, and Cyhalofop-butyl Residues in Agricultural Products Using Liquid Chromatography-Tandem Mass Spectrometry

An analytical method was developed to simultaneously determine pyridate, quizalofop-ethyl, and cyhalofop-butyl in brown rice, soybean, potato, pepper, and mandarin using LC-MS/MS. Purification was optimized using various sorbents: primary−secondary amine, octadecyl (C18) silica gel, graphitized carbon black, zirconium dioxide-modified silica particles, zirconium dioxide-modified silica particles (Z-SEP), and multi-walled carbon nanotubes (MWCNTs). Three versions of QuECHERS methods were then tested using the optimal purification agent. Finally, samples were extracted using acetonitrile and QuEChERS EN salts and purified using the Z-SEP sorbent. A six-point matrix-matched external calibration curve was constructed for the analytes. Good linearity was achieved with a determination coefficient ≥0.999. The limits of detection and quantification were 0.0075 mg/kg and 0.01 mg/kg, respectively. The method was validated after fortifying the target standards to the blank matrices at three concentration levels with five replicates for each concentration. The average recovery was within an acceptable range (70−120%), with a relative standard deviation <20%. The applicability of the developed method was evaluated with real-world market samples, all of which tested negative for these three herbicide residues. Therefore, this method can be used for the routine analysis of pyridate, quizalofop-ethyl, and cyhalofop-butyl in agricultural products.

Residue, dissipation and dietary intake risk assessment of tolfenpyrad in four leafy green vegetables under greenhouse conditions

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A QuEChERS-GC–MS/MS method was used to detect tolfenpyrad in leafy green vegetables.

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Half-lives of tolfenpyrad were 2.0–6.8 d in greenhouse-grown leafy green vegetables.

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PHI of tolfenpyrad was suggested as 21 d in BCL and 28 d in BBL, SOL and LSL.

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The potential health risk of tolfenpyrad was acceptable in leafy green vegetables.

A novel and accurate analytical method for the determination of tolfenpyrad in four leafy green vegetables, Brassica bara L., Spinacia oleracea L., Lactuca sativa L. and Brassica chinensis L., was developed and applied to investigate the residue distribution and dietary risk under greenhouse conditions. The established approach was determined to be adequate, with recoveries of 79.2%–92.9% and relative standard deviations < 8%. Tolfenpyrad dissipated relatively rapidly in four leafy green vegetables. Terminal residues of tolfenpyrad were below 0.5 mg/kg (maximum residue limit for Brassica bara L. set by China) in leafy green vegetables collected 28 d after the last application. Due to risk quotient values < 100%, the residue levels of tolfenpyrad in leafy green vegetables collected 21 days after the last application were deemed safe for consumers. The results provide field data for the reasonable use and dietary risk assessment of tolfenpyrad in leafy green vegetables.

Residues Analysis and Dissipation Dynamics of Broflanilide in Rice and Its Related Environmental Samples

Herein, we present a method for the quantitative analysis of broflanilide residues in water, soil, and rice samples from a paddy field in Jiangxi Province, China. The quick, easy, cheap, effective, rugged, and safe (QuEChERS) method was optimized for the extraction and purification of broflanilide residues. Residual broflanilide concentrations in different matrices were then determined by high-performance liquid chromatography (HPLC). The calibration curve of broflanilide showed good linearity in all matrices for concentrations between 0.005 and 1 mg·L⁻¹, with a correlation coefficient greater than 0.99. The matrix effect varied from −69% to −54%, indicating matrix suppression. The average recoveries ranged between 85.82% and 97.46%, with relative standard deviations of 3.29%–8.15%. The limits of detection ranged from 0.16 to 1.67 μg·kg⁻¹, and the limits of quantification were in the range of 0.54 to 5.48 μg·kg⁻¹. Dissipation dynamic tests indicated broflanilide half-lives of 0.46–2.46, 2.09–5.34, and 1.31–3.32 days in soil, water, and rice straw, respectively. Broflanilide was dissipated more rapidly in water than in soil and rice straw. More than 90% of broflanilide residues dissipated within 14 days. The final residues of broflanilide in rice were all below LOQ at harvest.

Comparative study on the nutrients, heavy metals and pesticide composition of some locally produced and marketed rice varieties in Nigeria

The nutrients, heavy metals and pesticide concentrations of an imported (Gold) and three locally produced and marketed rice varieties (Samples B-mass, C-R8 and D-CP) in Nigeria were investigated using standard techniques. All the rice varieties contained considerable amounts of moisture, ash, protein, lipid and carbohydrate but were low in crude fibre. The local rice varieties contained higher (P < 0.05) amounts of tryptophan and tyrosine than the imported rice. Sample C had the highest amino acids contents compared with other rice varieties. The threonine contents of the control and sample B were higher than WHO standards. Lead and mercury were not detected in all the rice varieties while the levels of cadmium, arsenic, chromium and thallium were within permissible range. The rice varieties contained considerable amounts of selenium, calcium, iron, manganese, zinc, phosphorous, boron, cobalt, Vitamins A, D, B6, thiamine, riboflavin, niacin and cobalamin with insignificant amounts of pesticide residues.

Assessment of strobilurin fungicides' content in soya-based drinks by liquid micro-extraction and liquid chromatography with tandem mass spectrometry

Seven strobilurin fungicides were pre-concentrated from soya-based drinks using dispersive liquid-liquid micro-extraction (DLLME) with a prior protein precipitation step in acid medium. The enriched phase was analysed by liquid chromatography (LC) with dual detection, using diode array detection (DAD) and electrospray-ion trap tandem mass spectrometry (ESI-IT-MS/MS). After selecting 1-undecanol and methanol as the extractant and disperser solvents, respectively, for DLLME, the Taguchi experimental method, an orthogonal array design, was applied to select the optimal solvent volumes and salt concentration in the aqueous phase. The matrix effect was evaluated and quantification was carried out using external aqueous calibration for DAD and matrix-matched calibration method for MS/MS. Detection limits in the 4-130 and 0.8-4.5 ng g(-1) ranges were obtained for DAD and MS/MS, respectively. The DLLME-LC-DAD-MS method was applied to the analysis of 10 different samples, none of which was found to contain residues of the studied fungicides.

Ultra-high performance liquid chromatography tandem high-resolution mass spectrometry study of tricyclazole photodegradation products in water

This paper reports the study of the photodegradation reactions that tricyclazole can naturally undergo, under the action of sunlight, in aqueous solutions of standard tricyclazole and of the commercial BEAM(TM) formulation. The analyses are carried out by ultra-high performance liquid chromatography technique coupled with high-resolution tandem mass spectrometry. Analysis of both tricyclazole and BEAM(TM) water solutions undergone to hydrolysis does not evidence new chromatographic peaks with respect to the not treated solutions. On the contrary, analysis of the same samples subjected to sunlight irradiation shows a decreased intensity of tricyclazole signal and the presence of new chromatographic peaks. Two photodegradation products of tricyclazole have been identified, one of which has been also quantified, being the commercial standard available. The pattern is similar for the solutions of the standard fungicide and of the BEAM(TM) formulation. The results obtained from eco-toxicological tests show that toxicity of tricyclazole standard solutions is greater than that of the irradiated ones, whereas toxicity levels of all the BEAM(TM) solutions investigated (non-irradiated, irradiated, and hydrolyzed) are comparable and lower than those shown by tricyclazole standard solutions. Experiments performed in paddy water solution show that there is no difference in the degradation products formed.

Photocatalytic degradation of molinate in aqueous solutions

In this study, the degradation of molinate through heterogeneous photocatalysis, using two different types of the semiconductor TiO2 as photocatalyst, as well as through homogeneous treatment, applying the photo-Fenton reaction, has been investigated. As far as heterogeneous photocatalysis is concerned, the degradation of the pesticide follows apparent first-order kinetics, while the type of the catalyst and the pH value of the solution affect the degradation rate. The effect of the addition of electron scavengers (H2O2 and K2S2O8) was also studied. In the case of photo-Fenton-assisted system, the degradation also follows pseudo-first-order kinetics. Parameters such as iron's and electron scavenger's concentration and inorganic ions strongly affect the degradation rate. The extent of pesticide mineralization was investigated using dissolved organic carbon (DOC) measurements. The toxicity of the treated solution was evaluated using the Microtox test based on the luminescent bacteria Vibrio fischeri. The detoxification and mineralization efficiency was found to be dependent on the system studied, and although it did not follow the rate of pesticide disappearance, it took place in considerable extent. The study of the photodegradation treatment was completed by the determination of the intermediate by-products formed during the process, which was carried out using LC-MS/MS technique and led to similar compounds with both processes.

Ultrasensitive detection of deltamethrin by immune magnetic nanoparticles separation coupled with surface plasmon resonance sensor

Small molecules or analytes present in trace level are difficult to be detected directly using conventional surface plasmon resonance (SPR) sensor, due to its small changes in the refractive index induced by the binding of these analytes on the sensor surface. In this paper, a new approach that combines SPR sensor technology with Fe3O4 magnetic nanoparticles (MNPs) assays is developed for directly detecting of deltamethrin in soybean. The Fe3O4 MNPs conjugated with antibodies specific to antigen serves as both labels for enhancing refractive index change due to the capture of target analyte, and "vehicles" for the rapid delivery of analyte from a sample solution to the sensor surface. Meanwhile, SPR direct detection format without Fe3O4 MNPs and gas chromatography (GC) analysis were conducted for detection of deltamethrin in soybean to demonstrate the amplification effect of Fe3O4 MNPs. A good linear relationship was obtained between SPR responses and deltamethrin concentrations over a range of 0.01-1 ng/mL with the lowest measurable concentration of 0.01 ng/mL. The results reveal that the detection sensitivity for deltamethrin was improved by 4 orders of magnitude compared with SPR direct detection format. The recovery of 95.5-119.8% was obtained in soybean. The excellent selectivity of the present biosensor is also confirmed by two kinds of pesticides (fenvalerate and atrazine) as controls. This magnetic separation and amplification strategy has great potential for detection of other small analytes in trace level concentration, with high selectivity and sensitivity by altering the target-analyte-capture agent labeled to the carboxyl-coated Fe3O4 MNPs.

Rapid simultaneous detection of multi-pesticide residues on apple using SERS technique

A rapid and straightforward method has been employed to simultaneously detect two pesticides (thiram and methamidophos (MTD)) on apple surface using surface enhanced Raman scattering (SERS) technique. In the experiment, ethanol was dropped onto the contaminated apple surface for pesticide extraction and then gold@silver core-shell nanorods (Au@Ag NRs) were added to generate the SERS signals of the pesticides. Under a laser excitation at 632.8 nm, prominent SERS peaks of blended contaminants were observed, which were chosen to characterize and quantify their concentration. It was found that the SERS intensity of these two peaks changed as a function of the concentration ratio of thiram to MTD. In addition, a better SERS enhancement performance of Au@Ag NRs was demonstrated compared with that of gold nanorods. Our experimental results show that the lowest detectable concentration on apple surfaces is ∼4.6 × 10(-7) M for thiram and ∼4.4 × 10(-4) M for MTD. This study provides a straightforward method for the simultaneous detection of multiple pesticides on fruit surfaces, which is important for food safety and human health.

Laboratory and field dissipation of penoxsulam, tricyclazole and profoxydim in rice paddy systems

Rice cultivation relies on pesticide applications to ensure high yields. However, the regular use of pesticides seriously affects the quality of neighboring surface water systems. Thus complete knowledge of the environmental fate and dissipation of pesticides in the paddy rice environment should become available. So far only a few studies have provided comprehensive assessment of the dissipation of pesticides under the submerged cultivation conditions followed in rice. Thus, laboratory and 2-year field studies were performed to assess the dissipation of two new generation rice herbicides (penoxsulam and profoxydim) and one of the most important rice fungicides (tricyclazole). A good agreement between laboratory and field experiments was observed with a faster dissipation of penoxsulam and tricyclazole under field conditions. Profoxydim was the least persistent chemical (DT50 soil<1d; DT50 water 0.5-1.2d), followed by penoxsulam which persisted for longer particularly in the water compartment (DT50water=3.8-5.9d). Tricyclazole was the most persistent pesticide, especially in the soil compartment with DT50 values of 44.5-84.6 (field) and 197d (laboratory). These results could be utilized for the assessment of the environmental risk associated with the use of those pesticides in rice cultivation and the determination of potential mitigation measures for minimizing the risk for contamination of neighboring natural water resources.

HPLC method development and validation of chromafenozide in paddy

A simple and efficient HPLC-UV method was developed and validated for determination of chromafenozide in paddy as there was no previous report on record in this regard. The residue analysis method of chromafenozide, its dissipation and final residue in paddy along with soil were also studied after field treatment. Residues of chromafenozide were extracted and purified from paddy and soil followed by liquid/liquid partitioning, chromatographic column and determination by HPLC equipped with PDA detector. The separation was performed on a Phenomenex Luna RP C(18) (250 × 4.6 mm i.d, 5 μm particle size) column at room temperature. The mean accuracy of analytical method were 94.92 %, 95.38 %, 94.67 % and 96.90 % in straw, grain, soil and field water respectively. The precision (repeatability) was found in the range of 1.30 %-9.25 % for straw/grain, 1.27 %-11.19 % in soil; 1.0 %-9.25 % in field water. The precision (reproducibility) in straw/grain was ranging from 2.2 % to 12.1 %, in soil it from 2.0 % to 11.7 %. The minimum detectable concentration was 0.01 mg kg(-1). The degradation of chromafenozide formulation in rice, soil and water was determined and results showed that chromafenozide as wettable powder formulation degraded with the half-lives of about 4.4 and 2.9 days in paddy plant and soil respectively for double recommended dose. The results indicated that the developed method is easier and faster then could meet the requirements for determination of chromafenozide in paddy.

Chromatographic determination of fungicides in biological and environmental matrices. New achievements

The newest results in the chromatographic analysis of synthetic and natural fungicides present in biological and environmental matrices are collected and critically evaluated. Examples of the employment of gas chromatography, liquid chromatographic technologies, such as thin-layer chromatography and high-performance liquid chromatographic methods as well as electrically driven systems are presented. The advantages and disasdvantages of the various chromatographic technologies are briefly discussed and the efficacies of the methodologies are compared.