Characterization of different parts of litchi fruit using UHPLC-QExactive Orbitrap.

Litchi fruit is consumed across the globe for its high nutritional value and taste. The qualitative profiling of litchi fruit has been carried out by using ultra-high-performance liquid chromatography with QExactive high-resolution accurate mass spectrometry. Acidified water: methanol: acetonitrile (1:1:1) extracts from individual parts (skin, pulp, and seed) of matured litchi, were subjected to LC-MS analysis with electrospray ionization in full MS-ddMS2 mode as a non-target approach. The data was processed through compound discoverer software by the use of mzCloud and ChemSpider databases, for compound identification. We identified 77 compounds with protonated or deprotonated forms based on the polarity and their characteristic fragments are within ± 4 ppm mass error and retention time ± 0.1 min for parent and fragments. Hypoglycin B is the first time reported in litchi fruit along with hypoglycin A. Further, we verified the distribution of the identified components and differentiation of three different parts of litchi through principal component analysis. Supplementary Information: The online version contains supplementary material available at 10.1007/s13197-022-05577-z.

Analysis of aflatoxins and ochratoxin a in chilli powder using ultrahigh performance liquid chromatography with fluorescence detection and tandem mass spectrometry.

Chilli powder, a popular spice, is predominantly contaminated with aflatoxins (AFs) and ochratoxin A (OTA), posing a menace to public health. As no validated method exists for the simultaneous and direct analysis of AFs and OTA in chilli powder, it was imperative to develop one to ensure their effective monitoring and promote trade. In this research, we developed and validated a multi-mycotoxin analysis method that allows the simultaneous determination of AFs (AFB1, AFB2, AFG1 and AFG2) and OTA in chilli powder with high sensitivity, accuracy and precision. The optimised sample preparation workflow started with the extraction of chilli powder (25 g) with methanol-water (100 mL, 80:20). An aliquot (3 mL) was cleaned on a multi-mycotoxin, immunoaffinity column (AFLAOCHRA PREP®) and analysed using ultrahigh performance liquid chromatography with fluorescence (UHPLC-FLD) and tandem mass spectrometric (LC-MS/MS) detection in a single chromatographic run. The method performance was evaluated through intra- and inter-laboratory validation (ILV) studies, and also by analysing a certified reference material. A direct analysis using UHPLC-FLD (without derivatisation) provided the limits of quantification (LOQ) of 0.25 and 1 ng/g for AFs and OTA, respectively, while the LOQ for all these mycotoxins in LC-MS/MS was 0.5 ng/g. These LOQs are much lower than the maximum levels (MLs) specified by the European Commission. The recoveries of these analytes at LOQ and higher levels were above 75% (RSDr < 12%). The ILV study demonstrated satisfactory method-reproducibility (RSDR < 25%). The analysis of the certified reference material provided accuracies of AFs and OTA in the range of 83-101%. The analysis by UHPLC-FLD and LC-MS/MS provided very similar results. The incurred levels of B1 in market samples were estimated with a precision-RSD of < 6%. Considering its efficiency and alignment with the regulatory requirements, this method can be implemented for the routine analysis of AFs and OTA in chilli powder.

Coupling the high-resolution LC-MS characterisation of the phenolic compounds with the antimicrobial and antibiofilm properties of helencha (Enydra fluctuans Lour.).

This study reports the polyphenol profile of helencha (Enydra fluctuans Lour.), an underutilised, aquatic leafy vegetable, based on high resolution accurate mass analysis. The methanolic extract of helencha leaves was screened by ultra-high performance liquid chromatography with quadrupole time of flight mass spectrometry (LC-QToF-MS). An in-house developed database of phytochemical metabolites was referred for compound identifications. Based on the detection of the pseudomolecular ion and at least one molecule-specific fragment ion (each with < 5 ppm of mass error), 25 potentially-bioactive phenolic compounds were putatively identified. These included 6 flavonols, 4 phenolic acids, 3 lignans, 3 flavones and 1 each of flavanol, flavanone, dihydroflavonol, tetramethoxyflavone, isoflavonoid and methylated flavonol. In addition, 3 unclassified compounds are also reported. The helencha extract showed antibiofilm properties with a potent bacteriostatic activity against the clinical isolates of Pseudomonas aeruginosa, a human pathogenic bacteria. The complementary molecular docking studies indicated strong binding interactions of the identified compounds with the active site of LasR protein of P. aeruginosa. The in vitro and in silico study results would be useful to develop novel neutraceutical products based on helencha-extract and design new lead compounds to control the biofilm producing pathogenic microorganisms. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at (10.1007/s13197-021-04968-y).

Determination of Colistin B in Chicken Muscle and Egg Using Ultra-High-Performance Liquid Chromatography-Tandem Mass Spectrometry.

Colistin, an imperative member of the polymyxin group, is a cationic peptide antibiotic. Itis also known as polymyxin E, but this peptide antibiotic has been forbidden for human consumption due to its high toxicity. Regrettably, this antibiotic is utilized as a feed additive and veterinary drug for animals. Due to the toxicity of colistin, the presence of its residue in the animal system represents a threat to human health regarding the consumption of meat, especially chicken. A novel method was proposed for quantifying colistin B in chicken muscles and eggs using ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). In this method, extraction of colistin B from samples was achieved by mixing the sample with acidified methanol:water (1/1, v/v), followed by centrifugation and filtration by a membrane filter excluding solid-phase extraction (SPE) clean up, as well as evaporation steps. The analysis was conducted by optimized liquid chromatography-tandem mass spectrometry (LC-MS/MS), and method performance was assessed in terms of the limit of quantitation, specificity, selectivity, precision, linearity and recovery in coherence with the guidelines of SANTE and the Commission Decision 2002/657/EC. The result obtained from the study showed the limit of quantitation (LOQ) as 10 µg Kg-1 for muscles and 5 µg Kg-1 for eggs, with acceptable recoveries along with precision. The linearity was plotted in the range of 5-25 µg L-1 (solvent) for egg and 10-50 µg Kg-1 (matrix-matched) for muscles. The result of average recoveries showed the value of 70-94% (3.3-12% relative standard deviation (RSD)) for chicken muscles and 88-107% (2.5-18.6% RSD) for egg samples, which meets the criteria for acceptability of method according to both SANTE and 2002/657/EC guidelines. This proposed protocol provides a cost-effective solution for food testing labs by reducing the cost of the sample preparation by 60% along with the time required for SPE cleanup. Further, the optimized method was also tested on real samples collected from nearby provinces in Solan city, Himachal Pradesh, India, and three out of 20 muscles were found to have colistin B in the range of 50-560 µg Kg-1.

Profiling of polyphenols in phalsa (Grewia asiatica L) fruits based on liquid chromatography high resolution mass spectrometry.

The aim of the study was to screen the metabolite profile of phalsa (Grewia asiatica), an underutilized fruit crop, using liquid chromatography-high resolution mass spectrometric analysis. A total of 50 compounds were tentatively identified based on their molecular mass and characteristic fragment ions, each with less than 5 ppm of mass error. These compounds included 21 flavonols, 2 dihydroflavonols, 7 flavones, 3 flavanols, 6 anthocyanins, 3 isoflavonoids, 2 phenolic acids, 2 flavanones, and 4 other phenolics. Flavonols were the predominant group of compounds, representing around 52.6% of the total phenolics. The paper has also discussed the potentiality of phalsa as an emerging functional food for the management of various human diseases in relation to the existing literature.

Improved analysis of captan, tetrahydrophthalimide, captafol, folpet, phthalimide, and iprodione in fruits and vegetables by liquid chromatography tandem mass spectrometry.

An improved liquid chromatography tandem mass spectrometry method is reported for the determination of residues of captan (+tetrahydrophthalimide), captafol, folpet (+phthalimide), and iprodione in fruits and vegetables. The optimized electrospray ionization parameters (high cone gas flow, and a low desolvation temperature) did not result in degradation of target compounds, rather they provided a significant advantage over the conventional GC-MS/MS methods, which lack sensitivity and repeatability. Strategies for minimizing losses in recovery of these compounds during sample preparation included cryogenic comminution, extraction with acidified ethyl acetate or acetonitrile, and dilution of the final extract with acidified water prior to LC-MS/MS analysis. The method performance complied with the SANTE/11813/2017 guidelines, with recoveries in the range of 70-120% at the LOQ of 0.01 mg/kg across the tested matrices at various pHs. The efficiency of the method was reflected in its precision (RSDs < 10%) for incurred residues.

Targeted phenolic profiling of Sauvignon blanc and Shiraz grapes grown in two regions of India by liquid chromatography-tandem mass spectrometry.

The phenolic compounds play an important role in production of quality grapes and wines. The current investigation focused on optimization of an extraction method for targeted analysis of 33 phenolic compounds in grapes by liquid chromatography tandem mass spectrometry (LC-MS/MS). The optimized method was successfully used for phenolic profiling of two wine grape varieties, Sauvignon blanc (white) and Shiraz (red) originated from Pune and Nasik regions of Maharashtra State, India. The optimized sample preparation procedure involved liquid-liquid extraction with acidified methanol by vortexing for 2 min followed by analysis on LC-MS/MS. The limit of quantification of the targeted compounds was in the range of 29 to 411 µg/L. The results indicated that skin of both varieties contained the highest amount of flavonols (69.47 ± 14.74 mg/kg in Sauvignon blanc and 129.47 ± 10.05 mg/kg in Shiraz) compared to pulp. The highest amounts of flavan-3-ols were present in grape seed collected from the Pune region (2016.84 ± 14.73 mg/kg in Sauvignon blanc and 1945.06 ± 32.69 mg/kg in Shiraz). The concentration of stilbenes was the highest in grape skin (0.13 ± 0.52 to 5.78 ± 5.45 mg/kg) compared to seed and pulp of both varities. Hydroxybenzoic acid (vanillin), hydroxycinnamic acid (p-coumaric acid) and anthocyanins (oenin, malvidin, cyanidin and kuromanin) were found only in Shiraz variety. The results of antioxidant activity (FRAP and DPPH assay) indicated the highest scavenging activity in seed (978.64 ± 56.23 to1133.38 ± 143.65 µMol TE/g DW FRAP and 594.93 ± 37.94 to 631.94 ± 56.45 µMol TE/g DW in DPPH). The phenolic contents in Sauvignon blanc and Shiraz grapes between Pune and Nasik regions did not have any significant difference.

Amelioration of diabetic nephropathy using pomegranate peel extract-stabilized gold nanoparticles: assessment of NF-κB and Nrf2 signaling system.

BACKGROUND: Diabetic nephropathy (DN), an end-stage renal disorder, has posed a menace to humankind globally, because of its complex nature and poorly understandable intricate mechanism. In recent times, functional foods as potential health benefits have been gaining attention of consumers and researchers alike. Rich in antioxidants, the peel and seed of pomegranate have previously demonstrated protection against oxidative-stress-related diseases, including cardiovascular disorders, diabetes, and cancer. PURPOSE: This study was designed to investigate the ameliorative role of pomegranate peel extract-stabilized gold nanoparticle (PPE-AuNP) on streptozotocin (STZ)-induced DN in an experimental murine model. METHODS: Following the reduction methods, AuNP was prepared using the pomegranate peel ellagitannins and characterized by particle size, physical appearance, and morphological architecture. Modulatory potential of PPE-AuNP was examined through the plethora of biochemical and high throughput techniques, flow cytometry, immunoblotting, and immunofluorescence. RESULTS: The animals treated with PPE-AuNP markedly reduced the fasting blood glucose, renal toxicity indices, and serum TC and TG in a hyperglycemic condition. As evident from an increased level of plasma insulin level, PPE-AuNP normalized the STZ-induced pancreatic ß-cell dysfunction. The STZ-mediated suppression of endogenous antioxidant response was restored by the PPE-AuNP treatment, which reduced the generation of LPO as well as iROS. Furthermore, the hyperglycemia-mediated augmentation of protein glycation, followed by the NOX4/p-47phox activation, diminished with the application of PPE-AuNP. The histological and immunohistochemical findings showed the protective efficacy of PPE-AuNP in reducing STZ-induced glomerular sclerosis and renal fibrosis. In addition, it reduced proinflammatory burden through the modulation of the MAPK/NF-κB/STAT3/cytokine axis. Simultaneously, PI3K/AKT-guided Nrf2 activation was evident upon the PPE-AuNP application, which enhanced the antioxidant response and maintained hyperglycemic homeostasis. CONCLUSION: The findings indicate that the use of PPE-AuNPs might act as an economic therapeutic remedy for alleviating DN.

High throughput residue analysis of paraquat and diquat involving hydrophilic interaction liquid chromatographic separation and mass spectrometric determination.

A selective, sensitive and robust LC-MS/MS method is reported for the determination of the residues of paraquat and diquat in various fruit matrices, including grape, apple and pomegranate. The extraction with acidified water (0.1 M HCl) at 80°C (15 min) offered superior recoveries for both analytes with a significantly lower matrix effects as compared to the extraction with acidified methanol by the methods reported in the existing literature. The optimised HPLC conditions on hydrophilic interaction liquid chromatography (HILIC) columns, when coupled with electrospray ionisation-tandem mass spectrometry, offered their limit of quantification at 0.01 mg kg-1. The analysis on an XBridge HILIC column required a thorough optimisation of the gradient programme to induce chromatographic separation and minimise matrix effects. This was not necessary when a CORTECS HILIC column was used, which provided selective and sensitive analysis within 5 min runtime using isocratic flow. Isotopically labelled internal standards corrected the recoveries of both analytes within 70-120% (RSD < 20%). For the first time, the applications of high resolution accurate mass analysis in the 'time of flight - multiple reaction monitoring' mode have been demonstrated as a complementary means of targeted screening of these compounds at 0.01 mg kg-1 level. The method has a strong potential for applications in both official control and by those involved in food production for checking compliance with the EU MRLs.

High-sensitivity direct analysis of aflatoxins in peanuts and cereal matrices by ultra-performance liquid chromatography with fluorescence detection involving a large volume flow cell.

This paper reports a sensitive and cost effective method of analysis for aflatoxins B1, B2, G1 and G2. The sample preparation method was primarily optimised in peanuts, followed by its validation in a range of peanut-processed products and cereal (rice, corn, millets) matrices. Peanut slurry [12.5 g peanut + 12.5 mL water] was extracted with methanol: water (8:2, 100 mL), cleaned through an immunoaffinity column and thereafter measured directly by ultra-performance liquid chromatography-fluorescence (UPLC-FLD) detection, within a chromatographic runtime of 5 minutes. The use of a large volume flow cell in the FLD nullified the requirement of any post-column derivatisation and provided the lowest ever reported limits of quantification of 0.025 for B1 and G1 and 0.01 µg/kg for B2 and G2. The single laboratory validation of the method provided acceptable selectivity, linearity, recovery and precision for reliable quantifications in all the test matrices as well as demonstrated compliance with the EC 401/2006 guidelines for analytical quality control of aflatoxins in foodstuffs.

A simultaneous screening and quantitative method for the multiresidue analysis of pesticides in spices using ultra-high performance liquid chromatography-high resolution (Orbitrap) mass spectrometry.

A novel screening and quantitation method is reported for non-target multiresidue analysis of pesticides using ultra-HPLC-quadrupole-Orbitrap mass spectrometry in spice matrices, including black pepper, cardamom, chili, coriander, cumin, and turmeric. The method involved sequential full-scan (resolution = 70,000), and variable data independent acquisition (vDIA) with nine consecutive fragmentation events (resolution = 17,500). Samples were extracted by the QuEChERS method. The introduction of an SPE-based clean-up step through hydrophilic-lipophilic-balance (HLB) cartridges proved advantageous in minimizing the false negatives. For coriander, cumin, chili, and cardamom, the screening detection limit was largely at 2 ng/g, while it was 5 ng/g for black pepper, and turmeric. When the method was quantitatively validated for 199 pesticides, the limit of quantification (LOQ) was mostly at 10 ng/g (excluding black pepper, and turmeric with LOQ = 20 ng/g) with recoveries within 70-120%, and precision-RSDs <20%. Furthermore, the method allowed the identification of suspected non-target analytes through retrospective search of the accurate mass of the compound-specific precursor and product ions. Compared to LC-MS/MS, the quantitative performance of this Orbitrap-MS method had agreements in residue values between 78-100%.

Optimization of multi-residue method for targeted screening and quantitation of 243 pesticide residues in cardamom (Elettaria cardamomum) by gas chromatography tandem mass spectrometry (GC-MS/MS) analysis.

Higher matrix interference makes the multi-residue pesticide analysis in spices more challenging. A simple, sensitive, and robust large-scale multi-residue method was developed for the rapid analysis of 243 pesticides in cardamom matrix by gas chromatography tandem mass spectrometry (GC-MS/MS). Prehydration of cardamom in 1:4 sample:water for 30 min improved the homogeneity and extractability. QuEChERS extraction followed by cleanup with 25 mg primary secondary amine, 100 mg C18, and 10 mg graphitized carbon black to 1 ml supernatant was used for sample preparation. Reconstitution of final extract in ethyl acetate reduced matrix co-extract up to 60%. The method was validated according to the SANTE/11,945/2015 guidelines. The limit of quantification was ≤0.01 mg kg-1, and the recovery was within 70.0-120.0%, with ≤20% RSD for the majority of pesticides. The method was used for screening market samples, and the detected residues were devoid of any risk of acute toxicity related to dietary exposure.

High-throughput mass spectrometry analysis revealed a role for glucosamine in potentiating recovery following desiccation stress in Chironomus.

Desiccation tolerance is an essential survival trait, especially in tropical aquatic organisms that are vulnerable to severe challenges posed by hydroperiodicity patterns in their habitats, characterized by dehydration-rehydration cycles. Here, we report a novel role for glucosamine as a desiccation stress-responsive metabolite in the underexplored tropical aquatic midge, Chironomus ramosus. Using high- throughput liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QToF-MS) analysis, biochemical assays and gene expression studies, we confirmed that glucosamine was essential during the recovery phase in C. ramosus larvae. Additionally, we demonstrated that trehalose, a known stress-protectant was crucial during desiccation but did not offer any advantage to the larvae during recovery. Based on our findings, we emphasise on the collaborative interplay of glucosamine and trehalose in conferring overall resilience to desiccation stress and propose the involvement of the trehalose-chitin metabolic interface in insects as one of the stress-management strategies to potentiate recovery post desiccation through recruitment of glucosamine.

Multiresidue Method for Targeted Screening of Pesticide Residues in Spice Cardamom (Elettaria cardamomum) by Liquid Chromatography with Tandem Mass Spectrometry.

A QuEChERS technique-based sample preparation method was optimized and validated in small cardamom to monitor the residues of 154 pesticides by LC with tandem MS. The proposed multiresidue method involved soaking powdered cardamom (2 g) in water (8 mL) for 30 min, followed by extraction with acetonitrile (10 mL). Cleanup by dispersive SPE was performed using primary secondary amine (25 mg/mL), C18 (25 mg/mL), and anhydrous magnesium sulfate (150 mg/mL). The method was validated as per the SANTE/11945/2015 guidelines at 5, 10, 50, and 100 ng/g spiking levels, and most of the analytes showed recoveries between 70 and 120% (with RSDs ≤20%). The LOQ of ≤10 ng/g was achieved for almost 90% of the target pesticides. The measurement uncertainties were evaluated at 100 ng/g, and the global uncertainty values were below 22% for all the analytes.

Determination of Triazines and Triazoles in Grapes Using Atmospheric Pressure Matrix-Assisted Laser Desorption/Ionization High-Resolution Mass Spectrometry.

A chromatography-free atmospheric pressure matrix-assisted laser desorption/ionization high-resolution mass spectrometry (AP-MALDI HRMS) method is described for the simultaneous and quantitative detection of triazines and triazoles in grapes. The analytes were detected reproducibly with high mass accuracy (mass error within 5 ppm) and further confirmed by collision-induced dissociation fragmentation in tandem MS. The LODs and LOQs for all the analytes were found to be in the nanogram per gram level (15-20 ng/g LOQ). Internal standard-normalized high-resolution accurate mass-extracted (HR-AM) peak intensities of the detected ions were used to generate the concentration response curves. Linearity (with R2 values around 0.99) was obtained for these curves within a concentration range of 20-200 ng/g of the individual analytes. The accuracy and precision of the method were further established using QC samples. Validation and performance comparison of the AP-MALDI HRMS method with an existing standard method using LC with triple quadrupole MS was carried out (evaluating sensitivity, accuracy, precision, and analysis time) using 20 table-grape field samples after QuEChERS extraction.

Optimization and Validation of a Residue Analysis Method for Glyphosate, Glufosinate, and Their Metabolites in Plant Matrixes by Liquid Chromatography with Tandem Mass Spectrometry.

A sensitive and accurate LC with tandem MS (MS/MS)-based method was developed and validated for the analysis of the herbicide glyphosate, its metabolite aminomethylphosphonic acid (AMPA), and glufosinate after derivatization with 9-fluorenylmethyl chloroformate (FMOC-Cl) in various plant matrixes. The method also covers direct analysis of the glufosinate metabolites 3-methylphosphinicopropionic acid (3-MPPA) and N-acetyl-glufosinate (NAG). The homogenized samples were extracted with 0.1% formic acid in water-dichloromethane (50 + 50). The aqueous layer was derivatized with FMOC-Cl, cleaned through an HLB SPE cartridge, and determined by LC-MS/MS. The sample size, extraction solvent, sample-to-solvent ratio, derivatization conditions, and cleanup procedure were thoroughly optimized, the LOQs of glyphosate, glufosinate, and AMPA were 0.5 ng/g in grape, corn (leaf and seed), and cotton (leaf, seed, and oil) and 2 ng/g in soybean and tea. The LOQs of NAG and 3-MPPA were 50 ng/g in all the test matrixes, except tea and soybean, for which the LOQ was 100 ng/g. In all cases, average recoveries were >80%. The method successfully performed the estimation of glyphosate in incurred corn and cotton leaf samples collected from supervised field trials.

Desiccation stress induces developmental heterochrony in Drosophila melanogaster.

Stressful environments are known to perturb developmental patterns in insects. In the purview of desiccation as a stressor, relatively little is known about the developmental consequences linked with desiccation tolerance. In this study, we have particularly focused on the exploration of the temporal profile of postembryonic development in response to desiccation exposure in Drosophila melanogaster and the associated trade-offs. We document a correlation between variations in 20-hydroxyecdysone levels and the altered timing of metamorphic events during the life cycle. Following desiccation, we observed an extension in the larval longevity whereas the duration of the pupal and adult stages was significantly shortened. Alternately, feeding of 20-hydroxyecdysone apparently led to the restoration of the normal temporal pattern of development in the desiccated group. In spite of the desiccation-responsive heterochronic shifts in development, the overall lifespan post recovery remained almost unaltered among the desiccated and undesiccated groups suggesting plasticity in developmental control. This observation reminisces 'canalization-like' phenomenon that buffers alterations in the overall lifespan. We thus identified a desiccationresponsive period in the lifespan of D. melanogaster during which variations in ecdysone levels are capable to alter the temporal course of development.

Evaluation of ozonation technique for pesticide residue removal and its effect on ascorbic acid, cyanidin-3-glucoside, and polyphenols in apple (Malus domesticus) fruits.

Ozonated water dip technique was evaluated for the detoxification of six pesticides, i.e., chlorpyrifos, cypermethrin, azoxystrobin, hexaconazole, methyl parathion, and chlorothalonil from apple fruits. Results revealed that ozonation was better than washing alone. Ozonation for 15 min decreased residues of the test pesticides in the range of from 26.91 to 73.58%, while ozonation for 30 min could remove the pesticide residues by 39.39-95.14 % compared to 19.05-72.80 % by washing. Cypermethrin was the least removed pesticide by washing as well as by ozonation. Chlorothalonil, chlorpyrifos, and azoxystrobin were removed up to 71.45-95.14 % in a 30-min ozonation period. In case of methyl parathion removal, no extra advantage could be obtained by ozonation. The HPLC analysis indicated that ozonation also affected adversely the ascorbic acid and cyanidin-3-glucoside content of apples. However, 11 polyphenols studied showed a mixed trend. Gallic acid, 3,4-dihydroxybenzoic acid, catechin, epicatechin, p-coumaric acid, quercetin-3-O-glucoside, quercetin, and kaempferol were found to decrease while syringic acid, rutin, and resveratrol were found to increase in 30-min ozonation.

Adsorption-desorption and leaching behavior of kresoxim-methyl in different soils of India: kinetics and thermodynamic studies.

The sorption and leaching behavior of kresoxim-methyl was explored in four different soils, viz., clay, sandy loam, loamy sand, and sandy loam (saline), representing vegetables and fruits growing regions of India. Adsorption of kresoxim-methyl in all the soils reached equilibrium within 48 h. The rate constants for adsorption and desorption at two different temperatures were obtained from the Lindstrom model, which simultaneously evaluated adsorption and desorption kinetics. The data for rate constants, activation energies, enthalpy of activation, entropy of activation, and free energy indicated physical adsorption of kresoxim-methyl on soil. The relative adsorptivity of the test soils could be attributed to different organic matter and clay contents of the soils. A good fit to the linear and Freundlich isotherms was observed for both adsorption as well as desorption. The groundwater ubiquity score (GUS) for different soils varied between 0 and 2.26. The GUS and leaching study indicated moderately low leaching potential of kresoxim-methyl. The adsorption on four soil types largely depended on the soil physicochemical properties such as organic carbon content, cation-exchange capacity, and texture of the soil.

Quantitative Screening of Agrochemical Residues in Fruits and Vegetables by Buffered Ethyl Acetate Extraction and LC-MS/MS Analysis.

A buffered ethyl acetate extraction method is proposed for the simultaneous analysis of 296 agrochemicals in a wide range of fruit and vegetable matrices by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The optimized quantity of acetate buffer (1% acetic acid + 0.5 g of sodium acetate per 10 g of sample) adjusted the pH of each test matrix to 5-6, which in turn significantly improved recoveries of acidic and basic compounds. The role of diethylene glycol (used in the evaporation step) on signal suppression of certain compounds was evaluated, and its quantity was optimized to minimize such an effect. The method was validated in grape, mango, drumstick, bitter gourd, capsicum, curry leaf, and okra as per the DG-SANCO/12571/2013 guidelines. Recoveries in the fortification range of 1-40 µg/kg were within 70-120% with associated relative standard deviations below 20% for most of the compounds. The method has potential for regulatory and commercial applications with a generic approach.