New analytical method for chlorpyrifos determination in biobeds constructed in Brazil: Development and validation.

A quick and efficient method was optimized and validated to determine chlorpyrifos in biobeds using ultraperformance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS). Chlorpyrifos was extracted from the matrix with 30 mL of a mixture of acetone, phosphoric acid and water 98:1:1 (v/v/v). After homogenization, centrifugation and filtration, 125 μL of the extract was evaporated and reconstituted in 5 mL of methanol acidified with 0.1% acetic acid. Validation was performed by studying analytical curve linearity (r2), estimated instrument and method limits of detection and limits of quantification (LODi, LODm, LOQi and LOQm, respectively), accuracy, precision (expressed as relative standard deviation, RSD), and matrix effect. Accuracy and precision were determined from the amount of pesticide recovered from biobed blank samples (i.e. without pesticide residue) spiked with chlorpyrifos at three different concentrations (2, 10 and 50 mg kg−1), with seven replicates at each concentration. For all three concentrations studied, the average recovery values obtained were between 96 and 115% with RSD values lower than 20%. The validated LOQ obtained was 2 mg kg−1 (from recovery studies) and the matrix effect observed was lower than ± 20%, which demonstrated that there was neither considerable suppression nor enhancement of the analyte signal. The biobed system efficiently degraded chlorpyrifos in both 1) simulation of accidental spillage and 2) application of diluted pesticide solution. In the latter case, all the values obtained at the final sampling time (14 months) were below the validated LOQm

Sistema Biobed Brasil: tecnologia para disposição final de efluentes contaminados com agrotóxicos originados a produção de frutas de clima temperado.

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O Efeito da Sinalização de Qualidade no Contexto de Serviços

Signaling theory states that signals are firms’ actions that communicate information about the quality of a product. The main purpose of this research is to investigate the effect of signal quality in a service context, through the investigation of the signaling effects of price and responsiveness in a service context. Perceived behavior control, regarded as an individual's perception of the ability to perform a behavior, was proposed as a moderator between signaling variables and perceived quality. Two experimental studies with factorial and inter-subject designs were conducted in order to test the hypotheses formulated from the literature review. Results from both experiments show that signaling quality through price and responsiveness can affect perceived quality. The second experiment supports the hypothesis of perceived behavior control moderation between price as a signaling variable and perceived quality, but not between responsiveness and perceived quality. These results and their implications are discussed in the final section of the paper

Analytical method validation to evaluate dithiocarbamates degradation in biobeds in South of Brazil.

In order to evaluate the efficiency of biobeds on DTC degradation, the aim of this study was to apply, optimize and validate a method to determine dithiocarbamate (mancozeb) in biobeds using gas chromatography-tandem mass spectrometry (GC-MS). The DTC pesticide mancozeb was hydrolysed in a tin (II) chloride solution at 1.5% in HCl (4 mol L−1 ), during 1 h in a water bath at 80 °C, and the CS2 formed was extracted in isooctane. After cooling, 1 mL of the organic layer was transferred to an auto sampler vial and analyzed by GC-MS. A complete validation study was performed and the following parameters were assessed: linearity of the analytical curve (r2 ), estimated method and instrument limits of detection and limits of quantification (LODm, LODi, LOQm and LOQi, respectively), accuracy (recovery%), precision (RSD%) and matrix effects. Recovery experiments were carried out with a standard spiking solution of the DTC pesticide thiram. Blank biobed (biomixture) samples were spiked at the three levels corresponding to the CS2 concentrations of 1, 3 and 5 mg kg−1 , with seven replicates each (n = 7). The method presented satisfactory accuracy, with recoveries within the range of 89?96% and RSD ≤ 11%. The analytical curves were linear in the concentration range of 0.05?10 µg CS2 mL−1 (r2 > 0.9946). LODm and LOQm were 0.1 and 0.5 mg CS2 kg−1 , respectively, and the calculated matrix effects were not significant (≤ 20%). The validated method was applied to 80 samples (biomixture), from sixteen different biobeds (collected at five sampling times) during fourteen months. Ten percent of samples presented CS2 concentration below the LOD (0.1 mg CS2 kg−1 ) and 49% of them showed results below the LOQ (0.5 mg CS2 kg−1 ), which demonstrates the biobeds capability to degrade DTC

Analytical method validation to evaluate dithiocarbamates degradation in biobeds in South of Brazil.

In order to evaluate the efficiency of biobeds on DTC degradation, the aim of this study was to apply, optimize and validate a method to determine dithiocarbamate (mancozeb) in biobeds using gas chromatography-tandem mass spectrometry (GC-MS). The DTC pesticide mancozeb was hydrolysed in a tin (II) chloride solution at 1.5% in HCl (4 mol L−1 ), during 1 h in a water bath at 80 °C, and the CS2 formed was extracted in isooctane. After cooling, 1 mL of the organic layer was transferred to an auto sampler vial and analyzed by GC-MS. A complete validation study was performed and the following parameters were assessed: linearity of the analytical curve (r2 ), estimated method and instrument limits of detection and limits of quantification (LODm, LODi, LOQm and LOQi, respectively), accuracy (recovery%), precision (RSD%) and matrix effects. Recovery experiments were carried out with a standard spiking solution of the DTC pesticide thiram. Blank biobed (biomixture) samples were spiked at the three levels corresponding to the CS2 concentrations of 1, 3 and 5 mg kg−1 , with seven replicates each (n = 7). The method presented satisfactory accuracy, with recoveries within the range of 89?96% and RSD ≤ 11%. The analytical curves were linear in the concentration range of 0.05?10 µg CS2 mL−1 (r2 > 0.9946). LODm and LOQm were 0.1 and 0.5 mg CS2 kg−1 , respectively, and the calculated matrix effects were not significant (≤ 20%). The validated method was applied to 80 samples (biomixture), from sixteen different biobeds (collected at five sampling times) during fourteen months. Ten percent of samples presented CS2 concentration below the LOD (0.1 mg CS2 kg−1 ) and 49% of them showed results below the LOQ (0.5 mg CS2 kg−1 ), which demonstrates the biobeds capability to degrade DTC.Made available in DSpace on 2018-12-23T23:36:30Z (GMT). No. of bitstreams: 1 Analyticalmethodvalidationtoevaluat...radationinbiobedsinSouthofBrazil.pdf: 518693 bytes, checksum: 4bc086ad520fd4f5b7eebd36b6ca3ae0 (MD5) Previous issue date: 2018-12-20bitstream/item/189181/1/Analytical-method-validation-to-evaluat...radation-in-biobeds-in-South-of-Brazil.pd

Determination of paraquat and diquat: LC-MS method optimization and validation.

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