kresoxim-methyl and pyrimethanil

The residue distribution and dissipation of pyrimethanil, fludioxonil, cyprodinil, and kresoxim-methyl, which were introduced during postharvest waxing treatments of apples, were investigated. In addition, different residue removal methods were tested for the four fungicides in apples, and the removal efficiencies were compared. A multiresidue analytical method was developed based on quick, easy, cheap, effective, rugged, and safe method (QuEChERS) for the determination of the fungicide residues in apples. The dissipation study demonstrated that there was no significant change of fungicide residue magnitude during a 40-day storage process under ambient temperature. The fungicide residues in apples by wax treatment were shown to be very much stable. The results of residue distribution study demonstrated that waxing treatment may help to reduce the risk of pesticide when only the pulp was consumed. In the residue removal study, results suggested that higher temperature and the addition of acetic acid can improve the residue removal efficiency.

Topics: Dioxoles; Food Contamination; Food Handling; Fruit; Fungicides, Industrial; Malus; Pesticide Residues; Pyrimidines; Pyrroles; Strobilurins

Although there is some evidence regarding the effect of solarization and biosolarization on pesticide degradation, information is still scarce. The aim of this study was to determine the effect of these disinfection techniques on the degradation of eight fungicides (azoxystrobin, kresoxin methyl, tebuconazole, hexaconazole, triadimenol, cyprodinil, pyrimethanil and fludioxonil) commonly used in pepper crops under greenhouse cultivation. Seventy-five 17-L pots filled with clay-loam soil were placed in a greenhouse during the summer season and then contaminated with the studied fungicides. Treatments consisted of different disinfection treatments, including a control without disinfection, solarization and biosolarization. For the solarization and biosolarization treatments, low-density polyethylene film was used as cover. Five pots per treatment were sampled periodically up to 90d after the beginning of each treatment and fungicide residues were analyzed by GC/MS. The results showed that both solarization and biosolarization enhanced fungicide dissipation rates with regard to the control treatment, an effect which was attributed to the increased soil temperature. Most of the fungicides studied showed similar behavior under solarization and biosolarization conditions. However, triadimenol was degraded to a greater extent in the biosolarization than in the solarization treatment, while fludioxonil behaved in the opposite way. The results confirm that both solarization and biosolarization contribute to pesticide dissipation and can therefore be considered alongside other soil disinfection techniques, as a bioremediation tool for pesticide-polluted soils.

Topics: Dioxoles; Environmental Restoration and Remediation; Fungicides, Industrial; Hot Temperature; Methacrylates; Phenylacetates; Photochemical Processes; Pyrimidines; Pyrroles; Soil; Soil Pollutants; Strobilurins; Triazoles

The coordination polymer [Zn(BDC)(H(2)O)(2)](n) was tested for extraction of pyrimethanil, ametryn, dichlofluanid, tetraconazole, flumetralin, kresoxim-methyl and tebuconazole from the medicinal plant Hyptis pectinata, with analysis using gas chromatography-mass spectrometry in selected ion monitoring mode (GC/MS, SIM). Experiments carried out at different fortification levels (0.1, 0.5 and 1.0 μg g(-1)) resulted in recoveries in the range 73-97%, and RSD values were between 5 and 12% for the [Zn(BDC)(H(2)O)(2)](n) sorbent. Detection and quantification limits ranged from 0.02 to 0.07 μg g(-1) and from 0.05 to 0.1 μg g(-1), respectively, for the different pesticides studied. The method developed was linear over the range tested (0.04-14.0 μg g(-1)), with correlation coefficients ranging from 0.9987 to 0.9998. Comparison between [Zn(BDC)(H(2)O)(2)](n) and the commercial phase C(18)-bonded silica showed good performance of the [Zn(BDC)(H(2)O)(2)](n) polymeric sorbent for the pesticides tested.

Topics: Adsorption; Aniline Compounds; Chemistry Techniques, Analytical; Chlorobenzenes; Gas Chromatography-Mass Spectrometry; Hyptis; Methacrylates; Microscopy, Electron, Scanning; Pesticides; Phenylacetates; Plant Extracts; Plants, Medicinal; Polymers; Pyrimidines; Solid Phase Extraction; Strobilurins; Triazines; Triazoles

In a 2 year experiment, residues in field-grown strawberries were investigated from the fungicides fenhexamid, pyrimethanil, tolylfluanid, and kresoxim-methyl resulting from different strategies, as regards the dose, number, and time of fungicide applications. Kresoxim-methyl was only used the first year and in full or no dose to control powdery mildew. In the first year, the highest concentrations analyzed were 0.66 mg kg(-1) for pyrimethanil and 0.63 mg kg(-1) for fenhexamid resulting from the use of recommended dose rates and a preharvest interval (PHI) of 10 days, thus not exceeding the Danish maximum residue limit (MRL) of 1 mg kg(-1). Tolylfluanid was used no later than 21 days before harvest, which left residue contents in the berries of 0.48 mg kg(-1), a value well below the MRL of 5 mg kg(-1). In the second year, fungicide residues found in the samples were generally lower, 0.39 and 0.03 mg kg(-1) for pyrimethanil and fenhexamid, respectively. No residues of kresoxim-methyl were found in any of the samples from the field trials, indicating that kresoxim-methyl residues had declined to a level well below the detection limit within the 28 day period between the last application and the harvest.

Topics: Botrytis; Chromatography, Liquid; Fragaria; Fruit; Fungicides, Industrial; Mass Spectrometry; Methacrylates; Pesticide Residues; Phenylacetates; Pyrimidines; Strobilurins

A method using headspace solid-phase microextraction (HS-SPME) then gas chromatography-mass spectrometry with selected ion monitoring (GC-MS, SIM) has been developed for determination of trace amounts of the fungicides pyrimethanil and kresoxim-methyl in soil and humic materials. Both fungicides were extracted on to a fused-silica fibre coated with 85 microm polyacrylate (PA). Response-surface methodology was used to optimise the experimental conditions. For soil samples the linear dynamic range of application was 0.004-1.000 microg g(-1) for pyrimethanil and 0.013-1.000 microg g(-1) for kresoxim-methyl. The detection limits were 0.001 microg g(-1) and 0.004 microg g(-1) for pyrimethanil and kresoxim-methyl, respectively. HP-SPME-GC-MS analysis was highly reproducible-relative standard deviations (RSD) were between 6.7 and 12.2%. The method was validated by analysis of spiked matrix samples and used to investigate the presence of pyrimethanil and kresoxim-methyl above the detection limits in soil and humic materials.

Topics: Gas Chromatography-Mass Spectrometry; Methacrylates; Molecular Structure; Phenylacetates; Pyrimidines; Sensitivity and Specificity; Soil; Strobilurins; Time Factors

A method for determination of trace amounts of the fungicides pyrimethanil and kresoxim-methyl in green groceries, previous headspace solid-phase microextraction (HSSPME), was developed using gas chromatography-mass spectrometry and selected ion monitoring (GC-MS, SIM). Both fungicides were extracted with a fused-silica fiber coated with 85 microm polyacrylate. The effects of pH, ionic strength, extraction and desorption times as well as the extraction temperature were studied. The linear concentration range of application was 12.5-250 ng g(-1) for both compounds, with detection limits of 1.8-2.0 ng g(-1) for pyrimethanil and 2.8-3.1 ng g(-1) for kresoxim-methyl. SPME/GC-MS analysis yielded good reproducibility (RSD between 7.4 and 15.0%). It was applied to check the eventual existence of pyrimethanil and kresoxim-methyl above the detection limits on grapes, strawberries, tomatoes and ketchup samples. The method validation was completed with spiked matrix samples. It can be applied as a monitoring tool in grapes, strawberries, tomatoes and ketchup samples.

Topics: Fruit; Fungicides, Industrial; Gas Chromatography-Mass Spectrometry; Methacrylates; Phenylacetates; Pyrimidines; Sensitivity and Specificity; Strobilurins