Fresh coconut (Cocos nucifera) water, a popular beverage in tropical countries, is often exposed to pesticide contamination due to agricultural practices. Thus, this work proposed the simultaneous determination of 36 pesticides in fresh coconut water samples using liquid-liquid extraction, drying assisted by a household microwave oven, and gas chromatography-mass spectrometry (GC-MS) analysis. Limits of detection varied from 5.4 (disulfoton) to 9.6 ng L-1 (parathion-methyl). Nine pesticide residues were detected (dimethoate, γ-HCH, β-HCH, 4,4’-dichlorodiphenyldichloroethylene, endosulfan II, 4,4’-dichlorodiphenyldichloroethane, 4,4’-dichlorodiphenyltrichloroethane, endrin ketone, and methoxychlor) with concentrations from < limit of quantification to 5,768.34 ± 1.64 ng L-1. Dimethoate was quantified in all samples, indicating its recent use. The proposed methodology offers several advantages, including the use of small sample volumes and solvent extraction, which eliminates the need for costly cartridges and reduces waste production. Additionally, the obtained results can be valuable for regulatory agencies, aiding in the mitigation of environmental damage and the protection of human health.

<p>In this article, the results of the study of the matrix effect in the determination of metals calcium, chromium, iron, nickel, copper, zinc, molybdenum, cadmium, barium and lead in base oil using Energy Dispersive X-Ray Fluorescence (EDX) are presented. Sensitivities obtained for each calibration curve were evaluated where calcium, chromium, copper, cadmium, barium and lead had the lowest sensitivities. In the case of cadmium, this parameter was lagging and the studies were not carried forward. The curves of the other metals in different base oils were evaluated for linearity. The elements chromium, copper, molybdenum and lead showed linearity problems in some cases. Therefore, curves in different base oils showed distinct mathematical behavior where the matrix effect was confirmed. The other curves were evaluated and existence of the matrix effect attributed to interference of C / H ratio was confirmed in the quantification of all elements. Metals iron, nickel and zinc exhibited the highest sensitivity and determination coefficients, showing that the method has application potential.</p>

We investigated Individual differences in susceptibility to methylmercury (MeHg) contamination and its relationship with polymorphisms of the detoxifying enzyme glutathione S-transferase (GST). In Brazil, some Amerindian tribes from the Amazon region have an increased level of mercury in their hair. Samples of hair and blood were taken from inhabitants of two villages in the Kayabi and Munduruku Amerindian communities to investigate mercury levels in association with genetic polymorphism of GSTs. Other molecular biological markers were also studied, such as hemoglobin, haptoglobin and glucose 6-phosphate dehydrogenase (G-6-PDH). Higher levels of mercury contamination were found in the Kayabi villagers, who had a null genotype (GSTM1 0/0, also denominated GSTM1 null) frequency of 26%, than in the Munduruku villagers, for which the null genotype frequency was 0%. Individuals with the GSTM1 null phenotype had higher concentrations of mercury in their hair than individuals with GSTM1+/+ phenotypes (F = 21.51, p < 0.0001). No association with other markers studied was observed. This study suggests that GSTM1 may be involved in the biotransformation of mercury in humans.

A interação do zinco com o DNA do fago lambda foi investigada utilizando a voltametria de pulso diferencial e a voltametria cíclica. Os métodos baseiam-se no monitoramento direto da corrente de redução e oxidação do zinco na ausência e na presença do DNA viral. Curvas de titulação do Zn2+ com o DNA do fago lambda foram obtidas nos intervalos de concentração 3,57 x 10-12 a 3,92 x 10-11 mol L-1 e 6,97 x 10-12 a 5,56 x 10-11 mol L-1. Estes dados foram utilizados para o cálculo da constante de dissociação do complexo e da estequiometria. O mecanismo da reação foi estudado utilizando a voltametria cíclica. Curvas do tipo I (corrente de oxidação do zinco) versus v½ (raiz quadrada da velocidade de varredura) mostraram que o processo oxidação-redução do zinco deixa de ser difusional na presença do DNA do fago lambda.

Binding of zinc to lambda phage DNA was investigated by differential pulse voltammetry and cyclic voltammetry. These methods rely on the direct monitoring of reduction and oxidation current of zinc in the absence and presence of this virion DNA. Titration graphs of Zn2+ with DNA were obtained in the concentration ranges from 3.57 x 10-12 to 3.92 x 10-11 mol L-1 and 6.97 x 10-12 to 5.56 x 10-11 mol L-1. These data were used to calculate the dissociation constant of the complex and the stoichiometry. The mechanism of this reaction was studied by cyclic voltammetry through curves I (oxidation current of Zn2+) versus v½ (square root of scan rate). These curves showed that the oxidation-reduction process of Zn2+ was not controlled by diffusion in the presence of lambda phage DNA.