Thienopyrimidine-derived multifunctional fluorescence sensor for the detection of Cu2+, Fe3+, and PPi in different solvents.

Hydrazine substituted thienopyrimidine, a new fluorophore, was used to synthesize a novel Schiff base R1 as a chemosensor via the condensation with p-formyltriphenylamine, and the structure was confirmed using nuclear magnetic resonance spectroscopy (NMR) and mass spectrometry (MS) analysis. When treated with Cu2+ in dimethylsulfoxide (DMSO)/H2O buffer, R1 showed a phenomenon of fluorescence quenching, which was reversible with the action of ethylenediaminetetraacetic acid (EDTA). When treated with Fe3+ in dimethylformamide (DMF)/H2O buffer, R1 exhibited the same phenomenon, but fluorescence was recovered with inorganic pyrophosphate (PPi) quantitatively. The complexation ratios for R1-Cu2+ and R1-Fe3+ were both 1:2, which were manifested by MS titrations and corresponding Job's plots. The limits of detection of R1 for Cu2+ and Fe3+ were 3.11 × 10-8 and 1.24 × 10-7 M, respectively. The sensing mechanism of R1 toward Cu2+ and Fe3+ was confirmed using density functional theory calculations and electrostatic potential analysis. Test strips of R1 were fabricated successfully for on-site detection of Cu2+ and Fe3+. In addition, R1 was applied to recognize Cu2+ and Fe3+ in actual water samples with satisfactory recovery.

Raman silent region - based method for detection of pesticides with cyano group.

Based on the fact that not all chemical substances possess good Raman signals, this article focuses on the Raman silent region signals of pesticides with cyano group. Under the optimized conditions of methanol-water (1:1, v/v) as the solvent, irradiation at 302 nm light source for 20 min, and the use of 0.5 mol/L KI as the aggregating agent, Surface-enhanced Raman spectroscopy (SERS) method for azoxystrobin detection was developed by the Raman silent region signal of 2230 cm-1, and verified by detecting the spiked grapes with different concentrations of azoxystrobin. Other four pesticides with cyano group also could be identified at the peak of 2180 cm-1, 2205 cm-1, 2125 cm-1, and 2130 cm-1 for acetamiprid, phoxim, thiacloprid and cymoxanil, respectively. When azoxystrobin or acetamiprid was mixed respectively with chlorpyrifos without cyano group, their SERS signals in the Raman silent region of chlorpyrifos were not interfered, while mixed with cymoxanil in different ratios (1:4, 1:1 and 4:1), respectively, each two pesticides with cyano group could be distinguished by the changes in the Raman silent region. In further, four pesticides with or without cyano group were mixed together in 1:1:1:1 (acetamiprid, cymoxanil, azoxystrobin chlorpyrifos), and each pesticide still could be identified even at 0.5 mg/L. The results showed that the SERS method combined with UV irradiation may provide a new way to monitor the pesticides with C≡N performance in the Raman silent region without interference from the food matrix.

Diverse bacteria colonizing leaves and the rhizosphere of lettuce degrade azoxystrobin.

Concerns about the possible effects of pesticide residues on both the environment and human health have increased worldwide. Bioremediation by the use of microorganisms to degrade or remove these residues has emerged as a powerful technology. However, the knowledge about the potential of different microorganisms for pesticide degradation is limited. This study focused on the isolation and characterisation of bacterial strains with the potential to degrade the active fungicide ingredient azoxystrobin. Potential degrading bacteria were tested in vitro and in the greenhouse, and the genomes of the best degrading strains were sequenced and analysed. We identified and characterised 59 unique bacterial strains, which were further tested in vitro and in greenhouse trials for their degradation activity. The best degraders from a foliar application trial in the greenhouse were identified as Bacillus subtilis strain MK101, Pseudomonas kermanshahensis strain MK113 and Rhodococcus fascians strain MK144 and analysed by whole genome sequencing. Genome analysis revealed that these three bacterial strains encode several genes predicted to be involved in the degradation of pesticides e.g., benC, pcaG, pcaH, however we could not find any specific gene previously reported to be involved in azoxystrobin degradation e.g., strH. Genome analysis pinpointed to some potential activities involved in plant growth promotion.

Multi-DNA Adduct and Abasic Site Quantitation In Vivo by Nano-Liquid Chromatography/High-Resolution Orbitrap Tandem Mass Spectrometry: Methodology for Biomonitoring Colorectal DNA Damage.

Epidemiological and mechanistic studies suggest that processed and red meat consumption and tobacco smoking are associated with colorectal cancer (CRC) risk. Several classes of carcinogens, including N-nitroso compounds (NOCs) in processed meats and heterocyclic aromatic amines (HAAs) and polycyclic aromatic hydrocarbons (PAHs) in grilled meats and tobacco smoke, undergo metabolism to reactive intermediates that may form mutation-inducing DNA adducts in the colorectum. Heme iron in red meat may contribute to oxidative DNA damage and endogenous NOC formation. However, the chemicals involved in colorectal DNA damage and the paradigms of CRC etiology remain unproven. There is a critical need to establish physicochemical methods for identifying and quantitating DNA damage induced by genotoxicants in the human colorectum. We established robust nano-liquid chromatography/high-resolution accurate mass Orbitrap tandem mass spectrometry (LC/HRAMS2) methods to measure DNA adducts of nine meat and tobacco-associated carcinogens and lipid peroxidation products in the liver, colon, and rectum of carcinogen-treated rats employing fresh-frozen and formalin-fixed paraffin-embedded (FFPE) tissues. Some NOCs form O6-carboxymethyl-2'-deoxyguanosine, O6-methyl-2'-deoxyguanosine, and unstable quaternary N-linked purine/pyrimidine adducts, which generate apurinic/apyrimidinic (AP) sites. AP sites were quantitated following derivatization with O-(pyridin-3-yl-methyl)hydroxylamine. DNA adduct quantitation was conducted with stable isotope-labeled internal standards, and method performance was validated for accuracy and reproducibility. Limits of quantitation ranged from 0.1 to 1.1 adducts per 108 bases using 3 µg of DNA. Adduct formation in animals ranged from ∼1 in 108 to ∼1 in 105 bases, occurring at comparable levels in fresh-frozen and FFPE specimens for most adducts. AP sites increased by 25- to 75-fold in the colorectum and liver, respectively. Endogenous lipid peroxide-derived 3-(2-deoxy-ß-d-erythro-pentofuranosyl)pyrimido[1,2-α]purin-10(3H)-one (M1dG) and 6-oxo-M1dG adduct levels were not increased by carcinogen dosing but increased in FFPE tissues. Human biomonitoring studies can implement LC/HRAMS2 assays for DNA adducts and AP sites outlined in this work to advance our understanding of CRC etiology.

Milk metabolome reveals pyrimidine and its degradation products as the discriminant markers of different corn silage-based nutritional strategies.

The purpose of this study was to evaluate the effect of 6 different feeding systems (based on corn silage as the main ingredient) on the chemical composition of milk and to highlight the potential of untargeted metabolomics to find discriminant marker compounds of different nutritional strategies. Interestingly, the multivariate statistical analysis discriminated milk samples mainly according to the high-moisture ear corn (HMC) included in the diet formulation. Overall, the most discriminant compounds, identified as a function of the HMC, belonged to AA (10 compounds), peptides (71 compounds), pyrimidines (38 compounds), purines (15 compounds), and pyridines (14 compounds). The discriminant milk metabolites were found to significantly explain the metabolic pathways of pyrimidines and vitamin B6. Interestingly, pathway analyses revealed that the inclusion of HMC in the diet formulation strongly affected the pyrimidine metabolism in milk, determining a significant up-accumulation of pyrimidine degradation products, such as 3-ureidopropionic acid, 3-ureidoisobutyric acid, and 3-aminoisobutyric acid. Also, some pyrimidine intermediates (such as l-aspartic acid, N-carbamoyl-l-aspartic acid, and orotic acid) were found to possess a high discrimination degree. Additionally, our findings suggested that the inclusion of alfalfa silage in the diet formulation was potentially correlated with the vitamin B6 metabolism in milk, being 4-pyridoxic acid (a pyridoxal phosphate degradation product) the most significant and up-accumulated compound. Taken together, the accumulation trends of different marker compounds revealed that both pyrimidine intermediates and degradation products are potential marker compounds of HMC-based diets, likely involving a complex metabolism of microbial nitrogen based on total splanchnic fluxes from the rumen to mammary gland in dairy cows. Also, our findings highlight the potential of untargeted metabolomics in both foodomics and foodomics-based studies involving dairy products.

Rapid determination of 2,4-diaminopyrimidine residues through sample pretreatment using immunomagnetic bead purification along with HPLC-UV.

To reduce matrix interference and realize simultaneous detection of multiple homologous compounds (trimethoprim (TMP), diaveridine (DVD), ormetoprim (OMP), baquiloprim (BQP), and aditoprim (ADP) in pig, cattle, chicken, and fish muscles), an immunomagnetic bead (IMB)-based sample purification pretreatment with HPLC-UV was developed. A broad-spectrum monoclonal antibody (mAb, named 14C6) was prepared and conjugated with carboxylic-acid-functionalized magnetic nanoparticles using the active ester method to obtain IMBs for sample purification. The extraction solvent was optimized based on the extraction efficiency. Good linearity was observed for all the five analytes (10-200 µg/kg) with the LOD and LOQ of 5 and 10 µg/kg, respectively. The mean recoveries ranged from 62.5% to 76.9%, while the coefficient of variation was <12.2%. The IMB method afforded greater sample purification and enrichment than those achieved with the SPE column-based conventional method. Hence, the IMB-based sample purification is a useful tool to determine 2,4-diaminopyrimidine residues in edible animal tissues.

Evaluation of acetamiprid and azoxystrobin residues and their hormonal disrupting effects on male rats using liquid chromatography-tandem mass spectrometry.

Endocrine-disrupting compounds as pesticides affect the hormonal balance, and this can result in several diseases. Therefore, the analysis of representative hormones with acetamiprid (AC) and azoxystrobin (AZ) was a good strategy for the investigation of the endocrine-disrupting activity of pesticides. Hence, a sensitive and rapid analytical method using liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed. The method was validated for the analysis of AC, AZ, estriol, estrone, progesterone, and testosterone in the serum, testis, and liver of rats. The correlation between the residues of pesticides and the disturbance of the endocrine system was evaluated. The different mass parameters, mobile phase types, analytical columns, injection volumes, and extraction solvents were compared to get the lowest limit of detection of the studied compounds. The detection limits of AC, AZ, estriol, estrone, progesterone, and testosterone were 0.05, 0.05, 1.0, 10, and 1.0 ng/ml, respectively. The method developed was applied to evaluate the changes in these hormones induced by the duration of exposure to AC and AZ in rat testis and serum. The hormones level in rat serum and testis had a significant decrease as they were oral gavage treated with different high concentrations of studied pesticides. Both pesticides were distributed in the body of rats by the multi-compartment model (liver, testis, and serum).

Combined 3D-{QSAR} and Molecular Docking Analysis of Thienopyrimidine Derivatives as Staphylococcus aureus Inhibitors.

The discovery of antibacterials is considered one of the greatest medical achievements of all time. In this work, a combination of three computational analyzes: 3D-QSAR, molecular docking and ADME evaluation were applied in thienopyrimidine derivatives intended toward gram-positive bacterium Staphylococcus aureus. The validity of 3D-QSAR model was tested with a set of data which is divided into a training and a test set. The two models constructed (CoMFA and CoMSIA) show good statistical reliability (q2 = 0.758; r2 = 0.96; r2pred = 0.783) and (q2 = 0.744; r2 = 0.97; r2pred = 0.625) respectively. In addition, docking methods were applied to understand the structural features responsible for the affinity of the ligands in the binding of S. aureus DNA gyrase. Drug likeness and ADME analysis applied in this series of new proposed compounds, have shown that the five lead molecules would have the potential to be effective drugs and could be used as a starting point for designing compounds against Staphylococcus aureus.

LC-MS/MS Estimation of Rociletinib Levels in Human Liver Microsomes: Application to Metabolic Stability Estimation.

BACKGROUND: Rociletinib (CO-1686; RLC) is a new, small molecule that is orally administered to inhibit mutant-selective covalent inhibitor of most epidermal growth factor receptor (EGFR)-mutated forms, including T790M, L858R, and exon 19 deletions, but not exon 20 insertions. Non-small-cell lung cancer (NSCLC) with a gene mutation that encodes EGFR is sensitive to approved EGFR inhibitors, but usually resistance develops, which is frequently mediated by T790M EGFR mutation. RLC is an EGFR inhibitor found to be active in preclinical models of EGFR-mutated NSCLC with or without T790M. METHODS: In silico drug metabolism prediction of RLC was executed with the aid of the WhichP450 module (StarDrop software package) to verify its metabolic liability. Second, a fast, accurate, and competent LC-MS/MS assay was developed for RLC quantification to determine its metabolic stability. RLC and bosutinib (BOS) (internal standard; IS) were separated using an isocratic elution system with a C18 column (reversed stationary phase). RESULTS: The developed LC-MS/MS analytical method showed linearity of 5-500 ng/mL with r2 ≥ 0.9998 in the human liver microsomes (HLMs) matrix. A limit of quantification of 4.6 ng/mL revealed the sensitivity of the analytical method, while the acquired inter- and intra-day accuracy and precision values below 4.63% inferred the method reproducibility. RLC metabolic stability estimation was calculated using intrinsic clearance (20.15 µL/min/mg) and in vitro half-life (34.39 min) values. CONCLUSION: RLC exhibited a moderate extraction ratio indicative of good bioavailability. The developed analytical method herein is the first LC-MS/MS assay for RLC metabolic stability.

Altered Follicular Fluid Metabolic Pattern Correlates with Female Infertility and Outcome Measures of In Vitro Fertilization.

Nearly 40-50% of infertility problems are estimated to be of female origin. Previous studies dedicated to the analysis of metabolites in follicular fluid (FF) produced contrasting results, although some valuable indexes capable to discriminate control groups (CTRL) from infertile females (IF) and correlate with outcome measures of assisted reproduction techniques were in some instances found. In this study, we analyzed in blind FF of 35 control subjects (CTRL = patients in which inability to obtain pregnancy was exclusively due to a male factor) and 145 IF (affected by: endometriosis, n = 19; polycystic ovary syndrome, n = 14; age-related reduced ovarian reserve, n = 58; reduced ovarian reserve, n = 29; unexplained infertility, n = 14; genetic infertility, n = 11) to determine concentrations of 55 water- and fat-soluble low molecular weight compounds (antioxidants, oxidative/nitrosative stress-related compounds, purines, pyrimidines, energy-related metabolites, and amino acids). Results evidenced that 27/55 of them had significantly different values in IF with respect to those measured in CTRL. The metabolic pattern of these potential biomarkers of infertility was cumulated (in both CTRL and IF) into a Biomarker Score index (incorporating the metabolic anomalies of FF), that fully discriminated CTRL (mean Biomarker Score value = 4.00 ± 2.30) from IF (mean Biomarker Score value = 14.88 ± 3.09, p < 0.001). The Biomarker Score values were significantly higher than those of CTRL in each of the six subgroups of IF. Posterior probability curves and ROC curve indicated that values of the Biomarker Score clustered CTRL and IF into two distinct groups, based on the individual FF metabolic profile. Furthermore, Biomarker Score values correlated with outcome measures of ovarian stimulation, in vitro fertilization, number and quality of blastocysts, clinical pregnancy, and healthy offspring. These results strongly suggest that the biochemical quality of FF deeply influences not only the effectiveness of IVF procedures but also the following embryonic development up to healthy newborns. The targeted metabolomic analysis of FF (using empowered Redox Energy Test) and the subsequent calculation of the Biomarker Score evidenced a set of 27 low molecular weight infertility biomarkers potentially useful in the laboratory managing of female infertility and to predict the success of assisted reproduction techniques.

LC-MS/MS method for the quantification of the anti-cancer agent infigratinib: Application for estimation of metabolic stability in human liver microsomes.

Infigratinib (INF) is a novel small molecule, administered orally, which acts as a human fibroblast growth factor receptors (FGFRs) inhibitor. FGFRs are a family of receptor tyrosine kinases (RTK) reported to be upregulated in various tumor cell types. In 1 December 2020, BridgeBio Pharma Inc. announced FDA approval of INF as a New Drug Application, granting it Priority Review for the treatment of cholangiocarcinoma (CCA). Thus, the current study aimed to establish a validated LC-MS/MS method to estimate the INF concentration in the HLM matrix. In silico prediction of INF metabolism was done using the StarDrop® WhichP450™ module to verify its metabolic stability. An accurate and efficient LC-MS/MS analytical method was developed for INF metabolic stability evaluation. INF and duvelisib (DVB) (internal standard; IS) were eluted using an isocratic mobile phase with a C18 column as a stationary reversed phase. The established LC-MS/MS method showed a linear range over 5-500 ng/mL (r2 ≥ 0.9998) in human liver microsomes (HLMs). The sensitivity of the method was confirmed at its limit of quantification (4.71 ng/mL), and reproducibility was indicated by inter- and intra-day accuracy and precision (within 7.3%). The evaluation of INF metabolic stability was assessed, which reflected an intrinsic clearance of 23.6 µL/min/mg and in vitro half-life of 29.4 min. The developed approach in the current study is the first LC-MS/MS method for INF metabolic stability assessment. Application of the developed method in HLM in vitro studies suggests that INF has a moderate extraction ratio, indicating relatively good predicted oral bioavailability.

Quantification of KRAS inhibitor sotorasib in mouse plasma and tissue homogenates using liquid chromatography-tandem mass spectrometry.

Sotorasib is a KRAS inhibitor with promising anticancer activity in phase I clinical studies. This compound is currently under further clinical evaluation as monotherapy and combination therapy against solid tumors. In this study, a liquid chromatography-tandem mass spectrometric method to quantify sotorasib in mouse plasma and eight tissue-related matrices (brain, liver, spleen, kidney, small intestine, small intestine content, lung, and testis homogenates) was developed and validated. Protein precipitation using acetonitrile was utilized in 96-well format to extract sotorasib and erlotinib (internal standard) from mouse plasma and tissue homogenates. Separation of the analytes was performed on an Acquity UPLC® BEH C18 column by gradient elution of methanol and 0.1% formic acid in water at a flow rate of 0.6 ml/min. Sotorasib was detected by a triple quadrupole mass spectrometer with positive electrospray ionization in selected reaction monitoring mode. A linear calibration range of 2-2,000 ng/ml of sotorasib was achieved during the validation. Accuracy values were in the range of 90.7-111.4%, and precision values (intra- and interday) were between 1.7% and 9.2% for all tested levels in all investigated matrices. The method was successfully applied to investigate the plasma pharmacokinetics and tissue accumulation of sotorasib in female wild-type mice.

Determination of azoxystrobin, topramezone, acetamiprid, fluometuron and folpet in their commercially available pesticide formulations by liquid chromatography.

A rapid, simple, precise and accurate high performance liquid chromatographic (HPLC) analytical method was developed and validated for the determination of the active substances (a.s.) azoxystrobin, topramezone, acetamiprid, fluometuron and folpet in their respective commercially available formulations. The method was used for the analysis of samples under the frame of the national quality control program of plant protection products in the Greek market. Chromatographic separation of the active substances from additives and co-formulants is achieved using isocratic elution with acetonitrile and 0.1% phosphoric acid solution (60:40 v/v) at a flow rate of 0.4 mL min-1 on a C18 monolithic column (Chromolith Performance-RP18e 100 × 4.6 mm) and UV detection at 230 nm. Validation parameters of the method fulfilled acceptability criteria. Recovery of all individual compounds was in the range 97.8-100.9%. Precision expressed as relative standard deviation was lower than the theoretical values of the modified Horwitz equation. Correlation coefficients of linearity of response were better than 0.999. The benefits of the proposed method are significant reduction in analysis time and total cost since all analytes were determined with the same extraction procedures and chromatographic system. Analysis of real samples for all active ingredients confirmed fitness for purpose of the suggested method.

Occurrence and impact of fungicides residues on fermentation during wine production- A review.

Continuous fungicide spraying is required to eliminate fungal pathogens on grapes. However, this practice is associated with several risks, including contamination and environmental imbalance, as well as toxicity to operators and the induction of resistance in pathogens. In addition, a strong correlation has been reported between the presence of fungicides and the occurrence of issues during alcoholic fermentation, resulting in negative impacts on the sensory quality of the final products. Numerous studies have evaluated residue concentrations of phytosanitary products in grapes, juices, and wines, and a significant number of studies have assessed the impact of different agrochemicals on bioprocesses. However, a review compiling the key results of these studies is currently lacking. This review incorporates results obtained in the last decade from research on the presence of fungicide residues, including azoxystrobin, boscalid, captan, copper, fenhexamid, folpet, pyraclostrobin, pyrimethanil and tebuconazole, and their effects on fermentation kinetics. Practical solutions to mitigate these problems, both in vineyards and industry, are also presented and discussed. This review highlights the constant high fungicidal agent concentrations (greater than 1 or 2 mg L-1) used throughout the winemaking process, with the impact of residues being of particular concern, especially with regard to their effect on yeast activity and the fermentation process. Thus, the adoption of methodologies that allow winemakers to control and trace these residues is an important step in avoiding or reducing fermentation problems throughout the winemaking process.[Figure: see text].

Identification of the metabolites of tofacitinib in liver microsomes by liquid chromatography combined with high resolution mass spectrometry.

Tofacitinib is an orally available Janus kinase inhibitor. The aim of this study was to investigate the metabolism of tofacitinib in mouse, rat, monkey, and human liver microsomes fortified with ß-nicotinamide adenine dinucleotide phosphate tetrasodium salt and uridine diphosphate glucuronic acid. The biotransformation was executed at a temperature of 37°C for 60 min, and the samples were analyzed by ultra-high performance liquid chromatography combined with high-resolution mass spectrometry (UHPLC-HRMS) operated in positive electrospray ionization mode. The structures of the metabolites were elucidated according to their retention times, accurate masses, and MS/MS spectra. Under the current conditions, a total of 13 metabolites, including 1 glucuronide conjugate, were detected and structurally proposed. Oxygenation of the pyrrolopyrimidine ring, oxygenation of piperidine ring, N-demethylation, oxygenation of piperidine ring side chain, and glucuronidation were the primary metabolic pathways of tofacitinib. Among the tested species, tofacitinib showed significant species difference. Compared with other species, rat showed similar metabolic profiles to those of humans. The present study provides some new information regarding the metabolism of tofacitinib in animals and humans, which would bring us considerable benefits for the subsequent studies focusing on the pharmacological effect and toxicity of this drug.

LC-QqQ-MS/MS methodology for determination of purine and pyrimidine derivatives in unifloral honeys and application of chemometrics for their classification.

The new liquid chromatographic-triple quadrupole tandem mass spectrometry (LC-QqQ-MS/MS) method for determination of purine and pyrimidine derivatives in honey produced by Apis mellifera was developed. 13 compounds were determined in total of 130 unifloral honey samples of 13 varieties: uracil, thymine, thymidine, xanthine, guanine, adenine, uridine, pseudouridine, xanthosine, inosine, hypoxanthine, guanosine and cytidine. The levels of some of these compounds varied between the specific honey types. The most abundant were uridine (up to 44.66 mg/kg), xanthine (up to 20.48 mg/kg) and xanthosine (up to 19.22 mg/kg). The data were evaluated by principal component analysis (PCA) and k-nearest neighbors (k-NN) classification (selected 9 and 8 honey types, respectively) to examine differences between the honey varieties allowing their discrimination based on purine and pyrimidine derivatives amounts. The data allowed to distinguish between 8 honey types (balanced accuracy 82%) and for most of the varieties obtained classification rates ranged from 96 to 100%.

Novel synthesized attapulgite nanoparticles-based hydrophobic monolithic column for in-tube solid-phase microextraction of thiosildenafil, pseudovardenafil, and norneosildenafil in functional foods.

In this study, a novel method which involved in-tube solid-phase microextraction (SPME) using an attapulgite (ATP) nanoparticles-based hydrophobic monolithic column was successfully developed. It was coupled with high-performance liquid chromatography-ultraviolet detection for the determination of three phosphodiesterase-5 (PDE-5) inhibitors, including thiosildenafil, pseudovardenafil, and norneosildenafil, in functional foods. The monolithic column was prepared by one-step polymerization, using 3-trimethoxysilylpropyl methacrylate-modified ATP nanoparticles and 1-butyl-3-vinylimidazolium bromide (VBIMBr) as the functional monomers, and ethylene glycol dimethacrylate (EDMA) as the cross-linker. The obtained poly(ATP-VBIMBr-EDMA) monolith was characterized by scanning electron microscopy equipped with energy-dispersive analysis of X-ray, Fourier transform infrared spectroscopy, thermogravimetric analysis, and X-ray diffraction. The adsorption capacity, up to 2.00 µg/cm calculated by the Langmuir isotherm model, was about six times that of the poly(VBIMBr-EDMA) monolith. Crucial factors affecting the extraction efficiency, including sample solvent, elution solvent, flow rates of sampling loading and elution, sample loading volume, and elution volume, were investigated in details. Under the optimal in-tube SPME conditions, the proposed method showed good reproducibility with run-to-run, column-to-column, and batch-to-batch relative standard deviations less than 7.2%, and low limits of detection of 0.5-0.9 ng/mL in real samples. Thiosildenafil was detected in four types of functional foods with the contents of 1.30-4.78 µg/g. This newly proposed in-tube SPME method based on poly(ATP-VBIMBr-EDMA) monolith may provide a simple, efficient, and promising alternative to daily monitoring of PDE-5 inhibitors in functional foods.

Simulating sulfosulfuron fate in soil under different weather scenarios to support weed management decisions.

BACKGROUND: Residual herbicides are an important component in many weed control strategies. Their herbicidal activity depends on their fate in soil, with respect to the required concentration for weed control in space and time. In this study, the effect of weather conditions on sulfosulfuron fate in soil, following pre-planting incorporation, and the predicted control efficacy of Egyptian broomrape in tomato, were analyzed for two sites using simulations in Hydrus-1D modeling software. Simulated concentration was compared to measured data from field experiments. RESULTS: Model evaluation against measured data from two fields, with weakly alkaline clay soils, showed high correlations between simulated and measured sulfosulfuron concentrations (r = 0.98 and 0.89). The ratio of measured to simulated concentration was relatively low (1.03) at the top 10-cm layer, in which the mean measured concentration was high (29.6 ng g-1 ). This ratio was higher (12.5) at the 30-60 cm depth, in which the mean measured concentration was lower (0.3 ng g-1 ). Simulations of sulfosulfuron fate in each site, using weather data from the years 2009 to 2019, revealed substantial variations in transport patterns. Thirty days after treatment, 16 out of the 22 years simulated for the two sites (11 at each site) resulted in concentrations lower than the critical value for Egyptian broomrape control throughout the soil profile. The data indicates that variation in sulfosulfuron fate is mainly due to differences in the cumulative precipitation. According to simulation results, cumulative precipitation above 20 or 10 mm during the first 10 or 20 days after treatment, respectively, is expected to reduce the efficiency of broomrape control. CONCLUSION: Considering weather effects when planning herbicide application could optimize herbicide use efficiency. A decision-support tool is presented, whose factors are the time gap and precipitation amount between sulfosulfuron application and tomato planting.

Evaluation of hematological parameters, oxidative stress and DNA damage in the cichlid Australoheros facetus exposed to the fungicide azoxystrobin.

Azoxystrobin (AZX) is a broad-spectrum systemic fungicide massively used worldwide. Its mode of action consists in the inhibition of mitochondrial respiration decreasing the synthesis of ATP and leading to oxidative stress in the target fungus. However, whether this effect occurs in non target organisms has been scarcely studied. The objectives of this work were (1) to evaluate biomarkers of oxidative stress, hematological, physiological and of genotoxicity in the native cichlid fish Australoheros facetus exposed to environmentally relevant concentrations of AZX and (2) to compare these biomarkers in different developmental stages using juvenile and adult fish (n = 6) exposed during 48 h. The exposure concentrations were 0 (negative control, C (-)), 0.05, 0.5, 5 and 50 µg/L AZX of the commercial formulation AMISTAR®. Blood was drawn to evaluate hematology, and DNA damage through the comet assay (CA) and micronucleus test (MN). Genotoxicity was observed by mean of both biomarkers in juvenile and adult fish at 50 µg/L AZX. Samples of liver and gills were used to determine antioxidant enzymes activity, hydrogen peroxide (H2O2) and malondialdehyde (MDA) contents. In juvenile fish inhibition of superoxide dismutase (SOD) was observed in liver at 0.05, 5 and 50 µg/L AZX and in gills at 5 and 50 µg/L AZX. Glutathione- S- transferases (GST) activity increased in gills at all AZX concentrations tested. In adult fish, increase of hepatic catalase (CAT) activity at 0.5 and 50 µg/L AZX and MDA content at 50 µg/L AZX were observed. In gills only H2O2 content showed changes at 50 µg/L AZX. The sensitivity showed by gills constitutes the first report about AZX toxicity in this organ. All these negative effects were observed in the range of realistic AZX concentrations, which warns of the possible consequences that it may have on the health of aquatic biota. Differences between juvenile and adult fish demonstrate the relevance of considering the developmental stage on the evaluation of biomarkers.

Statistical evaluation of analytical curves for quantification of pesticides in bananas.

The aim of this paper is to statistically validate the analytical curves of a chromatography method to identify and quantify azoxystrobin, difenoconazole and propiconazole residues in banana pulp, using QuEChERS and GC-SQ/MS. A matrix-matched calibration was used and analytical curves were estimated by weighted least squares regression (WLS), confirming heteroscedasticity for all compounds. Statistical tests were performed to confirm the quality adjustment of the proposed linear model. The correlation coefficient for azoxystrobin, difenoconazole and propiconazole were, respectively, 0.9985, 0.9966 and 0.9997 (concentration range: 0.05 and 2.0 mg kg-1). The limits of detection and quantification were, respectively, between 0.007 and 0.066 mg kg-1, and between 0.022 and 0.199 mg kg-1, below the maximum limits stipulated by Brazilian, American, and European legislation. Only difenoconazole had an insignificant matrix effect (6.8%). Thus, the weighted least squares method is shown to be a safe linear regression model, providing greater reliability of the results.