Maria Aparecida Liberato Milhome

Avaliação do potencial de contaminação de águas superficiais e subterrâneas por pesticidas aplicados na agricultura do Baixo Jaguaribe, CE

This study evaluated the potential of contamination of surface water and groundwater in the irrigated agriculture of Baixo Jaguaribe, in Ceara state, Brazil. The analysis was performed based on the criteria of the Environmental Protection Agency (EPA), the index of GUS and method of GOSS. These indexes have been based on physical and chemical properties of the active ingredients of each pesticide. The present paper assessed the main products, which are applied on crops in the irrigated agriculture of Baixo Jaguaribe, through survey in the region. The comparison between the models showed some potential for pesticide contamination in surface water and groundwater, and requires the constant monitoring of levels waste.

Removal of phenol and conventional pollutants from aqueous effluent by chitosan and chitin

The present study deals with phenol adsorption on chitin and chitosan and removal of contaminants from wastewater of a petroleum refinery. The adsorption kinetic data were best fitted to first- and second-order models for chitosan and chitin, respectively. The results of adsorption isotherms showed Langmuir model more appropriately described than a Freundlich model for both adsorbents. The adsorption capacity was 1.96 and 1.26 mg/g for chitin and chitosan, respectively. Maximum removal of phenol was about 7080% (flow rate: 1.5 mL/min, bed height: 18.5 cm, and 30 mg/L of phenol. Wastewater treatment with chitin in a fixed-bed system showed reductions of about 52 and 92% for COD and oil and greases, and for chitosan 65 and 67%, respectively. The results show improvement of the effluent quality after treatment with chitin and chitosan.

Evaluation of an analytical methodology using QuEChERS and GC-SQ/MS for the investigation of the level of pesticide residues in Brazilian melons.

A multiresidue method based on the sample preparation by modified QuEChERS and detection by gas chromatography coupled to single quadruple mass spectrometers (GC-SQ/MS) was used for the analysis of 35 multiclass pesticides in melons (Cucumis melo inodorus) produced in Ceara-Brazil. The rates of recovery for pesticides studied were satisfactory (except for the etridiazole), ranging from 85% to 117% with a relative standard deviation (RSD) of less than 15%, at concentrations between 0.05 and 0.20 mg kg(-1). The limit of quantification (LOQ) for most compounds was below the MRLs established in Brazil. The combined relative uncertainty (Uc) and expanded uncertainty (Ue) was determined using repeatability, recovery and calibration curves data for each pesticide. Analysis of commercial melons samples revealed the presence of pesticides bifenthrin and imazalil at levels below the MRLs established by ANVISA, EU and USEPA.

Multiresidue methods for determination of pesticides using SPME and SPE followed by GC-NPD system: a comparative study

Neste estudo, metodos multirresiduos usando extracao em fase solida (SPE) e microextracao em fase solida (SPME) sao comparados na determinacao de pesticidas em amostras aquosas. Parâmetros como tipo de fibras e espessura, solvente de eluicao, volume da amostra, tempo de equilibrio, coeficiente de particao e solubilidade foram investigados. Resultados satisfatorios foram obtidos para a analise de pesticidas usando cartuchos C18 e acetato de etila como eluente, com taxas de recuperacao entre 75-107%. As melhores condicoes para SPME foram com uma fibra PDMS 100 µm de espessura, volume de amostra de 40 mL, e tempo de equilibrio de 45 min. O metodo SPME e o mais adequado para a analise de pesticidas em agua, devido a sua rapidez e simplicidade e ao nao uso de solventes. Os limites de deteccao e quantificacao sao inferiores aos limites de concentracao maximos estabelecidos pelas autoridades brasileiras, sendo portanto aceitavel.

Validation and Uncertainty of the method for multiresidue analysis of 35 pesticides in melon using Gas Chromatography Coupled to Quadrupole Mass Spectrometry (GC-QP/MS)

QuEChERS method and detection in GC/SQ-MS were validated for the analysis of 35 pesticides in melon. Validation parameters (selectivity, linearity, LOD, LOQ, accuracy and precision) were determined according ABNT NBR 14029:2005. The recoveries rates for all the pesticides studied were from 63% to 117% with relative standard deviation (RSD) lower than 15% in the concentration range of 0.05 - 0.20 mg/kg. The limit of quantification (LOQ) for most compounds were below the MRLs established in Brazil. The combined relative uncertainty (Uc) and expanded uncertainty (Ue) was determined using repetitivity, recovery and calibration curves data for each pesticide.

Characterization of the Fatty Acids Present in Wastewaters from Production of Biodiesel Tilapia

Biodiesel obtained from oil extracted from the viscera of tilapia is a viable alternative in the replacement of petroleum fuels. However, during the purification step is performed biodiesel washing water is performed, which generates high effluent pollutant loads due to the reagents used and the very composition of the raw material. This study aims to characterize the fatty acids present in water from washing of the process of purifying biodiesel tilapia (Oreochromis niloticus). Fatty acid compositions were determined using gas chromatography (GC-FID). The results showed that the fatty acids present in greater quantities in the effluent were lauric (C12: 0), followed by myristic (C14: 0), palmitic (C16: 0), oleic (C18: 1), stearic (C18: 0), linolenic (C18: 3), and linoleic (C18: 2) acids. Therefore, the levels of oil and grease found in the rinse water from washing of the oil biodiesel tilapia are far above the allowed values above; thus they do not comply with Brazilian federal regulations.

Effect of ozonization in degradation of trifluralin residues in aqueous and food matrices

Abstract This study investigates the oxidation of trifluralin residues during ozonation in aqueous and food matrices (tomato). Domestic ozonation equipment with average production of 23.9 mg O3 L−1 h−1 was used in the tests. Modern chromatographic systems (SPME-GC-IT/MS/MS and QuEChERS-GC-IT/MS/MS) were applied for extraction and detection of trifluralin residue in fortified samples of ultrapure water, tap water, superficial water and tomato fruit. The samples were submitted to the ozonation process during 0, 5, 10 and 20 min. Treatment at 5 min was able to degrade 71.5% of herbicide trifluralin in surface water. The removal (%) in ultrapure water reached 83.4% after 20 min of ozonation. The degradation of trifluralin in fortified tomato samples (0.025–0.1 mg kg−1) were conducted with ozonation at 20 min, and it ranged from 84.4 to 92.7%. After treatment, levels of trifluralin in tomato remained within the established MRLs to EU, USEPA and ANVISA (Brazil). The data provided evidence that ozone is effective for removing trace trifluralin from water and foods.

Square Wave Adsorptive Stripping Voltammetry Determination of Chlorpyriphos in Irrigation Agricultural Water

This work describes the electroanalytical determination of Chlorpyriphos pesticide in natural waters using hanging mercury drop electrode allied to square wave adsorptive cathodic stripping voltammetry. The best responses were obtained in Britton‒Robinson buffer solutions at pH 2.0, using a frequency of 100 s–1, a scan increment of 5 mV, a square wave amplitude of 25 mV and an accumulation potential of–0.4 V during 60 s. Therefore, voltammetric responses showed the presence of one well-defined and irreversible reduction peak, at–1.08 V vs. Ag/AgCl/KCl 1.0 M, which involves two electrons in the reduction of carbon‒nitrogen bond in the N-heterocyclic system with the participation of protonation equilibrium preceding the electron transfer reaction. Analytical curves were constructed and compared to similar curves performed by gas chromatograph coupled to a selective nitrogen‒phosphorus detector, which demonstrates that the proposed methodology is suitable for determining contamination by Chlorpyriphos in complex samples.