RESUMO Catharanthus roseus (L.) G. Don é uma planta medicinal conhecida por importantes compostos aromáticos constituintes. Na literatura, não há estudos detalhados que elucidem os métodos de extração de compostos fenólicos para esta espécie. Portanto, o presente estudo teve como objetivo avaliar os parâmetros de maceração para determinar a concentração de fenóis totais em C. roseus. Os parâmetros de massa de planta, composição da fase extratora, tipo de homogeneização, tempo de extração e temperatura foram avaliados para melhorar as condições de extração. Os extratos das plantas foram submetidos à análise espectrofotométrica para cada parâmetro e a concentração de fenóis totais foi determinada. Após estabelecer condições ótimas, os extratos foram preparados a partir de cultivares de C. roseus, seguidos da avaliação da atividade antioxidante por espectrofotometria, conteúdo de ácidos fenólicos por CG-EM e dissimilaridade pelo método de pares de médias aritméticas não ponderadas. As condições ótimas de extração obtidas foram: 30 mg de tecido vegetal seco em 0.72 mL de fase de extração etanol: água, 50:50 (v/v), a 50 ºC por 1 h. A concentração média de fenóis totais foi de 30.3 mg g-1 equivalentes de ácido gálico (EAG) e 20.0 mg g-1 equivalentes de quercetina (EQ) para flavonoides. A atividade antioxidante determinada pelos métodos DPPH, ABTS e FRAP foi de 19.4, 11.8 e 23.3 mg g-1 de concentração equivalente de Trolox e atividade antioxidante (CETAA), respectivamente. Houve predomínio de ácidos ferúlico (42%-56%) e cafeico (21%- 52%) nos extratos de folhas de C. roseus. O processo de extração aumentou o teor de fenóis totais em 55%, de 18 para 28 mg EAG.
ABSTRACT Catharanthus roseus(L.) G. Don is a medicinal plant known for its important constituent aromatic compounds. In the literature, no detailed studies elucidating the methods of extraction of phenolic compounds for this species are available. Therefore, the present study was aimed at evaluating the maceration parameters for determining the total phenols content in C. roseus. The parameters of plant mass, extraction phase composition, homogenization type, extraction time, and temperature were evaluated in terms of improving the extraction conditions. The plant extracts were subjected to specific spectrophotometric analysis designed for each parameter, and the total phenols content was determined. After establishing the optimal conditions, the extracts were prepared from C. roseus cultivars, followed by evaluation of antioxidant activity using spectrophotometry, phenolic acid content using GC-MS, and dissimilarity using Unweighted Pair Group Method in combination with the Arithmetic Mean method. The optimal extraction conditions obtained were: 30 mg of dry plant tissue in 0.72 mL of extraction phase ethanol:water, 50:50 (v/v) at 50 °C for 1 h. The average total phenols content was 30.3 mg g-1 of gallic acid equivalents (GAE) and 20.0 mg g-1 of flavonoid quercetin equivalents (QE). The antioxidant activities determined using the DPPH, ABTS, and FRAP methods were 19.4, 11.8, and 23.3 mg g-1 of Trolox equivalent antioxidant capacity (TEAC), respectively. There was a predominance of ferulic (42%-56%) and caffeic (21%-52%) acids in the leaf extracts of C. roseus. The extraction process increased the total phenol content by 55%, from 18 to 28 mg GAE.
Resumo A contaminação de solo e plantas por metais pesados devido ao uso de águas poluídas na irrigação agrícola é motivo de grande preocupação. No presente estudo, áreas irrigadas com água do rio Vieira foram avaliadas quanto a contaminação por As, Cr, Cu, Ni, Pb e Zn. Para isso foram selecionadas duas áreas, uma a montante e outra a jusante da cidade de Montes Claros. A descarga de água residuária aumentou a concentração de As e Ni na água do rio Vieira; e, consequentemente, de As, Cr, Cu, Ni, Pb e Zn no solo; e de As e Zn em plantas forrageiras. No entanto, os teores de metais pesados no solo não excederam os limites internacionais recomendados. O índice de carga de poluição (PLI) e o fator de contaminação (CF) indicaram existência de poluição e contaminação moderada em solos a jusante da cidade de Montes Claros. O índice de risco ecológico potencial (RI) e o coeficiente de risco ecológico (Er) indicaram baixo risco ecológico, porém esses indicadores foram maiores no solo a jusante de Montes Claros. O As foi o único metal pesado que apresentou fator de transferência (TF) maior que os valores generalizados encontrados na literatura e índice de geoacumulação (Igeo) positivo, indicativo de poluição antropogênica.
Abstract There is great concern with soil and plant contamination by heavy metals due to the use of polluted water in agricultural irrigation. In this study, areas irrigated with Vieira River water were evaluated as to contamination by As, Cr, Cu, Ni, Pb and Zn. The Vieira River receives effluent from Montes Claros city, state of Minas Gerais, Brazil. To do so, two irrigated areas were selected, one upstream and one downstream of the Montes Claros city. Wastewater discharge increased the concentration of As and Ni in the water of Vieira River, and consequently, of As, Cr, Cu, Ni, Pb and Zn in the soil and of As and Zn in forage grasses. However, the content of heavy metals in the soil did not exceed the internationally recommended limits. Pollution load index (PLI) and contamination factor (CF) indicated the existence of pollution and moderate contamination in downstream soils of the city of Montes Claros. Potential ecological risk index (RI) and ecological risk factor (Er) indicated a low ecological risk, but these indicators were higher in downstream soils of Montes Claros. Arsenic (As) was the only heavy metal that featured a transfer factor (TF) higher than the widespread values found in literature and positive geoaccumulation index (Igeo), indicative of anthropogenic pollution.
Abstract In banana farming, the bagging of bunches with bags impregnated by pyrethroid insecticide is a practice that prevents damage to fruits caused by insect pests. The aim of this study was to monitor the presence and permanence of bifenthrin residue during the maturation of ‘Grande Naine’ banana by gas chromatography coupled to mass spectrometer in the selective ion mode (GC-MS-SIM). Fruits were from bagged and non-bagged bunches and the extraction of bifenthrin residue from peel and pulp was performed with QuEChERS and LSE-LTP (Liquid-Solid Extraction - Low Temperature Partitioning) methods. The maturation stages were characterized as 1; 3 and 7 depending on the fruit peel color. The bifenthrin recovery percentages in banana peel and pulp obtained by QuEChERS and LSE-LTP methods are between 97% and 117%, and therefore, within the criteria of acceptability for residues of agrochemicals according to the Brazilian legislation and vary according to the matrix. The mean bifenthrin concentrations in the peel of fruits from bagged bunches were 0.34 mg kg -1, 0.29 mg kg -1 and 0.10 mg kg -1 at stage 1 (harvest point); 3 and 7, respectively. No bifenthrin residue was detected in fruit pulp at any maturation stage.
In this study, a method of solid-liquid extraction and purification at low temperature (SLE-PLT) to determine 16 polycyclic aromatic hydrocarbons (PAHs) in sewage sludge was optimized and validated. The analyses were performed by HPLC-UV. The extraction phase, homogenization procedure, influence of pH, ionic strength and clean-up of the extracts were optimized. Recoveries were higher than 63.4% for 11 PAHs. The correlation coefficients were greater than 0.99 and limits of detection and quantitation were less than 0.060 and 0.15 µg g-1, respectively. These values were lower than the maximum residue limits of PAHs established by European legislation. SLE-PLT proved a more practical, economical method with fewer steps compared to Soxhlet extraction (reference method) for PAHs in sewage sludge.
This study optimized and validated the liquid-liquid extraction technique with partition at low temperature (LLE-PLT) for identification and quantification of four pesticides (chlorpyrifos, λ-cyhalothrin, permethrin, bifenthrin) in water samples. Analyses were performed by HPLC-UV. The technique was efficient for pesticide recovery with extraction exceeding 86%. Chromatographic response was linear for the four compounds in the 10-45 µg L-1 range, with correlation coefficients greater than 0.99. Limits of detection and quantitation were less than 3.5 µg L-1 and equal to 10 µg L-1, respectively. The proposed method was applied to 29 water samples from the Jaíba Project in northern Minas Gerais.
Components in complex matrices can cause variations in chromatographic response during analysis of pesticides by gas chromatography. These variations are related to the competition between analytes and matrix components for adsorption sites in the chromatographic system. The capacity of the pesticides chlorpyrifos and deltamethrin to be adsorbed in the injector and chromatographic column was evaluated by constructing three isotherms and changing the column heating rate to 10 and 30 ºC min-1. By using ANCOVA to compare the slope of calibration graphs, results showed that the higher the injector temperature (310 ºC) the lower the pesticide adsorption. Also, deltamethrin influenced the adsorption of chlorpyrifos on the column chromatographic.
Multiresidue methods for pesticides monitoring by GC are commonly employed, however, it is well known that the presence of compounds of the matrix introduces errors during the quantiûcation. The main consequence of matrix effect is an increasing or decreasing analyte signal after the GC saturation with extracts of matrix. In this paper, the influence of constituents of nine matrices on the quantification of the four pesticides by GC-ECD was studied. Variation of signal was evaluated by PCA and HCA, and results showed that the constituents of tomato increased the signal (until 300%), while extracts of apple decreased (until -20%). Variation the analyte signal in the presence of the matrix in respect to the same analyte in solvent (standard solution) also was observed, mainly for liver extract (until 270%).