Comparative Biological Half-Life of Penthiopyrad and Tebufenpyrad in Angelica Leaves and Establishment of Pre-Harvest Residue Limits (PHRLs).

To prevent pesticides from exceeding maximum residue limits (MRLs) in crops during export and shipment, it is necessary to manage residue levels during the pre-harvest stages. Therefore, the Republic of Korea establishes pre-harvest residue limits (PHRLs) per crop and pesticide. This study was conducted to set PHRLs for penthiopyrad and tebufenpyrad in angelica leaves, where the exceedance rates of MRLs are expected to be high. The LOQ of the analytical method used was 0.01 mg/kg and it demonstrated good linearity, with a correlation coefficient of 0.999 or higher within the quantitation range of 0.005 to 0.5 mg/kg. The recovery and storage stability accuracy values were in the range of 94.5-111.1%, within the acceptable range (70-120%, RSD ≤ 20%). The matrix effect for both pesticides was in the medium-to-strong range, and it did not significantly impact the quantitative results as a matrix-matched calibration method was employed. Using the validated method, residue concentrations of penthiopyrad 20 (%) EC and tebufenpyrad 10 (%) EC were analyzed. Both pesticides exhibited a decreasing residue trend over time. In Fields 1-3 and their integrated results, the biological half-life was within 2.6-4.0 days for penthiopyrad and 3.0-4.2 days for tebufenpyrad. The minimum value of the regression coefficient in the dissipation curve regression equation was selected as the dissipation constant. The selected dissipation constants for penthiopyrad in Fields 1-3 and their integration were 0.1221, 0.2081, 0.2162, and 0.1960. For tebufenpyrad, the dissipation constants were 0.1451, 0.0960, 0.1725, and 0.1600, respectively. The dissipation constant was used to calculate PHRL per field. Following the principles of the PHRL proposal process, residue levels (%) on PHI dates relative to MRLs were calculated, and fields for proposing PHRLs were selected. For penthiopyrad, since the residue level (%) was less than 20%, the PHRL for Field 3 with the largest dissipation constant was proposed. For tebufenpyrad, as the residue level (%) exceeded 80%, the PHRL proposal could not established. It is deemed necessary to reassess the MRL and 'guidelines for safe use' for tebufenpyrad in angelica leaves.

An LC-MS/MS Method for the Simultaneous Analysis of 380 Pesticides in Soybeans, Kidney Beans, Black Soybeans, and Mung Beans: The Effect of Bean Grinding on Incurred Residues and Partitioning.

The significance of sample grinding is frequently disregarded during the development of analytical methods, which are often validated with spiked samples that may not accurately reflect incurred residues. This study investigated the particle size of ground beans as a key factor in optimizing extraction efficiency in order to develop a simple quick, easy, cheap, effective, rugged, and safe (QuEChERS)-based modified method for identifying 380 pesticides in beans using liquid chromatography-tandem mass spectrometry. The efficacy of pesticide extraction was found to be significantly affected by particle size. With small particle sizes (>40 mesh), no supernatant was recovered after QuEChERS partitioning. Therefore, a simple modification was performed before partitioning. The modified method was validated for selective extraction of pesticides, limits of quantification, linearity, accuracy, and precision. This method is simple to implement and, therefore, useful for the analysis of pesticide residues in beans.

Factors Affecting Incurred Pesticide Extraction in Cereals.

This study investigated the effect of milling on the yields of incurred residues extracted from cereals. Rice, wheat, barley, and oat were soaked in nine pesticides (acetamiprid, azoxystrobin, imidacloprid, ferimzone, etofenprox, tebufenozide, clothianidin, hexaconazole, and indoxacarb), dried, milled, and passed through sieves of various sizes. The quick, easy, cheap, effective, rugged, and safe method and liquid chromatography-tandem mass spectrometry extracted and quantified the incurred pesticides, respectively. For rice and oat, the yields were higher for vortexed samples than for soaked samples. For rice, the yields improved as the extraction time increased from 1 to 5 min. The optimized method was validated based on the selectivity, limit of quantitation, linearity, accuracy, precision, and the matrix effect. For rice and barley, the average yields improved as the particle size decreased from <10 mesh to >60 mesh. For 40-60-mesh wheat and oat, all pesticides (except tebufenozide in oat) had the highest yields. For cereals, 0.5 min vortexing, 5 min extraction, and >40-mesh particle size should be used to optimize incurred pesticide extraction.

Monitoring and risk analysis of residual pesticides drifted by unmanned aerial spraying.

This study aimed to investigate the residual characteristics of pesticides drifted by unmanned aerial spray according to buffer strip, windbreak, and morphological characteristics of non-target crops, suggest prevention for drift reduction, and finally conduct a risk analysis on pesticides exceeding the maximum residue limit (MRL) or uniform level (0.01 mg/kg) of the positive list system (PLS). Non-target crops were collected around the aerial sprayed area (paddy rice) in Boryeong, Seocheon, and Pyeongtaek after UAV spray. When pesticides were detected in more than three samples, Duncan's multiple range test was performed. In cases where pesticides were detected in only two samples, an independent sample t-test was conducted (p < 0.05). The drift rate of pesticides tends to decrease by up to 100% as the buffer distance from aerial sprayed area increases or when a windbreak, such as maize, is present between two locations. Thus, the reduction of drifted pesticides could be effective if both factors were applied near the UAV spray area. Moreover, the residue of drifted pesticides was found to be the highest in leafy vegetables such as perilla leaves or leaf and stem vegetables such as Welsh onion, followed by fruit vegetables and cucurbits, owing to the morphological characteristics of crops. Therefore, selecting pulse or cereal such as soybean or maize as a farm product near the UAV spray area can be considered to minimize the drift. For pesticides that exceed the MRL or PLS uniform level, %acceptable dietary intake is 0-0.81% with no risk. Additionally, employing pesticides approved for both paddy rice and farm products in UAV spraying can effectively minimize instances where MRL or PLS are exceeded. Therefore, this study aims to provide farmers with effective guidelines for mitigating drift. Furthermore, we strive to promote stable and uninterrupted food production while facilitating the utilization of agricultural technologies such as UAV spraying to address labor shortages and ensure sustainable food security.

Validation of a Multi-Residue Analysis Method for 287 Pesticides in Citrus Fruits Mandarin Orange and Grapefruit Using Liquid Chromatography-Tandem Mass Spectrometry.

Since the introduction of the positive list system (PLS) for agricultural products in the Republic of Korea, the demand for a quick, easy multi-residue analysis method increased continuously. Herein, the quick, easy, cheap, effective, rugged, and safe (QuEChERS) technique combined with liquid chromatography−tandem mass spectrometry was employed to optimize a method for the multi-residue analysis of 287 pesticide residues in mandarin orange and grapefruit. Method validation was conducted in terms of selectivity, limit of quantitation (LOQ), linearity, accuracy, precision, and matrix effect. All the compounds at low spiking levels (1, 2.5, 5, or 10 mg/kg) could be quantified at LOQs lower than 0.01 mg/kg (PLS level). The linearity of the matrix-matched calibration curve for each compound is in the range 0.5−50 µg/L, and its coefficient of determination (R2) is >0.990. Satisfactory recovery values of 70−120% with a relative standard deviation of ≤20% are obtained for all compounds in the mandarin orange and grapefruit samples. A negligible matrix effect (−20−20%) is observed for more than 94.8% and 85.4% of the pesticides in mandarin orange and grapefruit, respectively. Therefore, this analytical method can contribute to pesticide residue analyses of citrus fruits for routine laboratory testing.

Dissipation and Residue Pattern of Dinotefuran, Fluazinam, Indoxacarb, and Thiacloprid in Fresh and Processed Persimmon Using LC-MS/MS.

Pesticides which are diluted and sprayed according to the pre-harvest interval (PHI) are generally decomposed and lost through various factors and pathways, and the leftover pesticides are known as residual pesticides. This study aims to determine the dissipation of residual amounts of dinotefuran, fluazinam, indoxacarb, and thiacloprid in persimmon and the changes in the concentration of various processing products. Pesticide spraying is performed in accordance with the GAP (good agricultue practice) of Korea, and the processed products are manufactured using a conventional method after removing the skin of persimmons. The modified QuEchERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) method and an optimized method using LC-MS/MS (liquid chromatography mass spectrometry) is implemented to analyze the residual pesticides. The linearity, recovery, and LOQ (limit of quantitation) are presented to verify the analysis method. The amount of residual pesticides tested decreases significantly in a time-dependent manner, regardless of the minimal dilution effect present due to growth. The residual concentration does not vary significantly during the processing stage despite the removal of the systemic pesticides, dinotefuran and thiacloprid. The residues of non-systemic pesticides, fluazinam and indoxacarb, are typically removed by the peeling removal and processing methods. The reduction factor of dinotefuran, whose residual concentration is increased, is less than 1, and the absolute amount of pesticides is decreased through processing. The results of this study can be used as the scientific basis data to ensure the safety of residual pesticides in processed products in the future.

Easy and effective analytical method of carbendazim, dimethomorph, and fenoxanil from Protaetia brevitarsis seulensis using LC-MS/MS.

Traditionally in Korea, Protaetia brevitarsis seulensis (white-spotted flower chafer) has been used as a medicine, and recently has attracted increased attention due to its antithrombotic efficacy. Some of spent mushroom compost or fermented oak sawdust, a feedstock for P. brevitarsis, were contaminated with three fungicides, carbendazim, dimethomorph, and fenoxanil, which could be transferred to the insect. This study was aimed to optimize a simple extraction method combined with liquid chromatography tandem mass spectrometry and apply it to the real samples. After the pulverized samples (5 g) were extracted with acetonitrile (10 mL) and formic acid (100 µL), fat and lipids in the samples were slowly precipitated at -20°C for 24 hours. After eight different clean-up methods were investigated, the mixture of 150 mg MgSO4/25 mg PSA/25 mg C18 was selected due to optimal recovery of the target compounds. Recovery (77.9%‒80.8% for carbendazim, 111.2%‒116.7% for dimethomorph, and 111.9%‒112.5% for fenoxanil) was achieved with reasonable relative standard deviation (<5.5%) The analytical method developed in this study was used to analyze three compounds in the 24 insect samples donated by the insect farm owners but no target compounds were detected. These results can provide important data for establishing the pesticide safety standards for P. brevitarsis before the medical applications.

Dissipation and Distribution of Picarbutrazox Residue Following Spraying with an Unmanned Aerial Vehicle on Chinese Cabbage (Brassica campestris var. pekinensis).

We assessed the residual distribution and temporal trend of picarbutrazox sprayed by agricultural multicopters on Chinese cabbage and considered fortification levels and flying speeds. In plot 2, 14 days after the last spraying, the residues decreased by ~91.3% compared with those in the samples on day 0. The residues in the crops decreased by ~40.8% of the initial concentration owing to growth (dilution effect) and by ~50.6% after excluding the dilution effect. As the flight speed increased, picarbutrazox residues decreased (p < 0.05, least significant deviation [LSD]). At 2 m s-1 flight speed, the residual distribution differed from the dilution rate of the spraying solution. The average range of picarbutrazox residues at all sampling points was 0.007 to 0.486, below the limit of quantitation -0.395, 0.005-0.316, and 0.005-0.289 mg kg-1 in plots 1, 2, 3, and 4, respectively, showing significant differences (p < 0.05, LSD). These results indicated that the residual distribution of picarbutrazox sprayed by using a multicopter on the Chinese cabbages was not uniform. However, the residues were less than the maximum residue limit in all plots. Accordingly, picarbutrazox was considered to have a low risk to human health if it was sprayed on cabbage according to the recommended spraying conditions.

Effective and rugged analysis of glyphosate, glufosinate, and metabolites in Tenebrio molitor larva (mealworms) using liquid chromatography tandem mass spectrometry.

Tenebrio molitor larva (mealworms) has recently attracted attention as a protein source for food and feed. The larva is generally fed with wheat bran, which can be possibly contaminated with glyphosate. To establish food safe standards, a rugged and effective analytical method for glyphosate, aminomethylphosphonic acid, glufosinate, and their metabolites including 3-methylphosphinico-propionic acid, and N-acetyl glufosinate, in mealworms was optimized using liquid chromatography tandem mass spectrometry. An anionic polar pesticide column was used due to its high suitability for glyphosate. Acidified water and acetonitrile were used to extract the target compounds without contribution from various fatty and pigment interferences derived from brownish insects. Seven different clean-up procedures ((1) 50 mg C18 (2) 20 mg C18/Z-sep (3) PRiME hydrophilic-lipophilic balance (HLB) cartridge (4) 75 mg Z-sep, (5) 75 mg Z-sep+, (6) EMR-lipid cartridge, and (7) 50 mg ENVI-Carb) were compared. Due to its simplicity and cost-effectiveness, PRiME HLB was selected for clean-up. The recoveries of the target compounds were ranged from 86 to 96% with < 20% relative standard deviations. Therefore, this simple and effective method can be applied for the two pesticides and their metabolites in other edible insects or high-fat matrices.

Optimization and validation of a method for the determination of acidic pesticides in cabbage and spinach by modifying QuEChERS procedure and liquid chromatography-tandem mass spectrometry.

A quick, easy, cheap, effective, rugged, and safe (QuEChERS) method was developed and combined with liquid chromatography-tandem mass spectrometry to analyze 12 acidic pesticides in cabbage and spinach. The extraction solvents, phase partition salts and sorbents effect was studied to optimize the method followed by dilution before sample injection. The extraction involved 5% formic acid in acetonitrile, and the liquid-liquid partition was salt-induced. Carbopack Z, a high surface area graphitized carbon black, was a new sorbent used in the clean-up. The results show that Carbopack Z effectively removes interferences with little loss of acidic pesticides. All tested pesticide recoveries were satisfactory when Carbopack Z was combined with C18 in the clean-up at optimized condition. After clean-up, the extract was subjected to 10-fold dilution to sufficiently reduce the matrix effect (<20%). The limit of quantification (LOQ) was 1-5 ng/g, and the mean recovery was between 95 and 110% with a relative standard deviation <20% (between 2% and 10%) for the spiking of three concentrations: 5, 50, and 500 ng/g. The extract was less pigmented in the modified QuEChERS method than its original version. Thus, the modified method is a useful alternative for investigating the acidic pesticide residues in cabbage and spinach.

Effect of Processing on Residual Buprofezin Levels in Ginseng Products.

This study determined residual buprofezin levels in fresh ginseng and evaluated their changes during processing. Supervised field trials were conducted at Yeongju, Geumsan, and Goesan, Korea. Buprofezin 12.5% EC was applied to 5-y ginseng in accordance with the Korean good agriculture practice (GAP). Samples were collected at 0, 7, 14, 21, and 30 d after the final application. On day 14 (GAP-equivalent preharvest date), the ginseng was processed to obtain dried and red ginseng. The average buprofezin concentrations on day 0 were 0.076 (Yeongju), 0.055 (Geumsan), and 0.078 mg kg-1 (Goesan). Residual concentrations increased as ginseng was processed into dried and red ginseng. Residue levels in dried ginseng manufactured by hot air drying were higher than in red ginseng obtained by steaming, hot air, and sunlight drying. However, the absolute amount of pesticides decreased by approximately 20-30% as a result of calculating the reduction factor considering the dry yield and moisture content. Therefore, the residual concentration in processed products may vary depending on the processing method, and it is deemed necessary to consider the processing yield and moisture content when evaluating the safety of residual pesticides in dried processed products.

Liquid Chromatography-Tandem Mass Spectrometry for the Simultaneous Analysis of 353 Pesticides in the Edible Insect Tenebrio molitor Larvae (Mealworms).

Tenebrio molitor larvae (mealworm) is an edible insect and is considered a future food. Using liquid chromatography-tandem mass spectrometry (LC-MS/MS), a novel method for simultaneous analysis of 353 target analytes was developed and validated. Various sample preparation steps including "quick, easy, cheap, effective, rugged, and safe" (QuEChERS) extraction conditions, number of acetonitrile-hexane partitions, and dispersive-solid phase extraction (dSPE) sorbents were compared, and the optimal conditions were determined. In the established method, 5 g of homogenized mealworms was extracted with acetonitrile and treated with QuEChERS EN 15662 salts. The crude extract was subjected to three rounds of acetonitrile-hexane partitioning, and the acetonitrile layer was cleaned with C18 dSPE. The final solution was matrix-matched and injected into LC-MS/MS (2 µL). For target analytes, the limits of quantitation (LOQs) were ≤10 µg/kg, and the correlation coefficient (r2) of calibration was >0.990. In recovery tests, more than 90% of the pesticides showed an excellent recovery range (70-120%) with relative standard deviation (RSD) ≤20%. For more than 94% of pesticides, a negligible matrix effect (within ±20%) was observed. The analytical method was successfully applied and used for the detection of three urea pesticides in 4 of 11 mealworm samples.

Optimized residue analysis method for broflanilide and its metabolites in agricultural produce using the QuEChERS method and LC-MS/MS.

Since broflanilide is a newly developed pesticide, analytical methods are required to determine the corresponding pesticide residues in diverse crops and foods. In this study, a pesticide residue analysis method was optimized for the detection and quantification of broflanilide and its two metabolites, DM-8007 and S(PFH-OH)-8007, in brown rice, soybean, apple, green pepper, mandarin, and kimchi cabbage. Residue samples were extracted from the produce using QuEChERS acetate and citrate buffering methods and were purified by dispersive solid-phase extraction (d-SPE) using six different adsorbent compositions with varying amounts of primary secondary amine (PSA), C18, and graphitized carbon black. All the sample preparation methods gave low-to-medium matrix effects, as confirmed by liquid chromatography-tandem mass spectrometry using standard solutions and matrix-matched standards. In particular, the use of the citrate buffering method, in combination with purification by d-SPE using 25 mg of PSA and a mixture of other adsorbents, consistently gave low matrix effects that in the range from -18.3 to 18.8%. Pesticide recoveries within the valid recovery range 70-120% were obtained both with and without d-SPE purification using 25 mg of PSA and other adsorbents. Thus, the developed residue analysis method is viable for the determination of broflanilide and its metabolites in various crops.

Optimization of a Simplified and Effective Analytical Method of Pesticide Residues in Mealworms (Tenebrio molitor Larvae) Combined with GC-MS/MS and LC-MS/MS.

An effective analytical method was optimized for residues including chlorpyrifos-methyl, deltamethrin, fenoxanil, thiobencarb and fludioxonil in mealworms, the larval form of Tenebrio molitor. They are listed for pest control during wheat cultivation and can be found in wheat-bran feed for growing mealworms in South Korea. Analytes were extracted using acetonitrile and salt packet. Four clean-up methods ((1) MgSO4 + 25 mg PSA + 25 mg C18; (2) MgSO4 + 50 mg PSA + 50 mg C18; (3) EMR-lipidTM tube; and (4) 10 mL n-hexane) were investigated and the method (1) was selected due to its robustness. Low-temperature precipitation of fat and proteins improved the recoveries. Recoveries from the Method (1) were satisfying with 70-120% with <20% relative SD at a spiking level of 0.01 mg/kg. With the simultaneous sample preparation, fenoxanil, thiobencarb and fludioxonil were analyzed by liquid chromatography tandem mass spectrometry (LC-MS/MS) and chlorpyrifos-methyl and deltamethrin by gas chromatography tandem mass spectrometry (GC-MS/MS). Quantification limits for LC-MS/MS and GC-MS/MS were 0.5 and 2.5 µg/L, respectively. No pesticides of interest were detected in 30 real samples collected across the nation. However, the data can be provided for establishing maximum residue limits for the pesticides in mealworms in response to the positive list system.