Oil emulsified in water is one of the most difficult mixtures to treat due to the good stability of emulsions, so there is a growing demand for more efficient methods for separating immiscible ...oil/water mixtures. In this context, the focus of this study was to obtain an adsorbent for the selective treatment of a simulated oily wastewater. To this aim, a modified hydrotalcite sample with hydrophobic and magnetic characteristics was prepared and characterized. Initially, the effect of sodium dodecyl sulfate (SDS) amount on the adsorbent characteristics was evaluated (266-800 mg
SDS
g
−1
LDH
). The hydrophobic hydrotalcite (LDH-SDS) containing 533 mg
SDS
g
−1
LDH
(LDH-SDS2) presented a higher interlayer space where the surfactant molecules were arranged perpendicular to the lamellae, allowing better access to the hydrotalcite pores and facilitating the selective adsorption of oil compounds. Moreover, the synergistic association of hydrophobic properties with super-wetting and effective adhesion oil to Fe
3
O
4
favoured the selective adsorption of the simulated oily wastewater onto the hydrophobic and magnetic hydrotalcite (LDH-MSDS), facilitating the post-treatment separation. The kinetic analysis demonstrated that the adsorption equilibrium was attained in 120 min and the pseudo-second order model was the most suitable for predicting the removal of total organic carbon (TOC) from the simulated oily wastewater. The Langmuir model described very well the equilibrium experimental data, with a maximum adsorption capacity for TOC removal using LDH-MSDS of 659.9 mg g
−1
. Therefore, the modified hydrotalcite prepared in this study showed intrinsic characteristics that make it a promising adsorbent for the selective treatment of oily wastewaters.
Mancozeb (MZ), a manganese- and zinc-containing ethylene-bis-dithiocarbamate, is a broad-spectrum fungicide. Harmful effects of this fungicide have been reported in nontarget organisms via a not ...fully understood mechanism. Drosophila melanogaster has provided remarkable contributions for toxicological studies. This work was aimed at evaluating the biochemical targets and implication of oxidative stress in MZ-mediated toxicity in drosophilas. Exposure of flies for fifteen days to MZ at 5 and 10 mg/mL through the diet impaired locomotor performance and induced fly mortality. In parallel, it caused lipid peroxidation and reactive oxygen species (ROS) formation and Mn overload. MZ inhibited superoxide dismutase and inducted catalase and glutathione S-transferase activities. Nitric oxide and reduced glutathione levels were significantly decreased by MZ. Heat shock proteins (HSP70 and HSP83) and Nrf2 mRNA levels were significantly augmented in MZ-exposed flies. Our study reinforced the use of Drosophila melanogaster as a reliable model for the study of biochemical targets of pesticides, and based on our data, MZ induced oxidative damage and Mn accumulation in a concentration-dependent manner. An adaptative cellular state was inducted by the lower concentration of pesticide, possibly contributing to the slighter damage observed.
A method based on microwave-induced combustion (MIC) was applied for medicinal plants digestion allowing further chlorine determination by potentiometry using ion-selective electrode (ISE). Sample ...masses ranging from 500 to 1000 mg were evaluated for MIC digestion. Water and 10, 25, 50, and 100 mmol/L NH4OH were investigated as absorbing solutions. The accuracy of the proposed method was evaluated by using certified reference materials (CRMs), by recovery tests (500 µg/g), and also by comparison with the results obtained by inductively coupled plasma optical emission spectrometry (ICP-OES) after microwave-assisted alkaline extraction (MAE). Using water or NH4OH solutions (10 to 100 mmol/L), recoveries close to 100% and relative standard deviation lower than 5% were obtained. Results were in agreement with CRMs values (better than 95%) and also with those values obtained by using the MAE method. The main advantage of the proposed method was the complete combustion of high sample mass (1000 mg) resulting in low quantification limit (12.5 µg/g) and chlorine determination at low concentration by ISE. Another advantage of the proposed method was the high chlorine stability in digests (up to 30 days of storage) even using water as absorbing solution, which is in agreement with green analytical chemistry recommendations. Finally, the proposed MIC method was applied for commercial medicinal plants and the chlorine concentration was in the range of 59.4 ± 1.4 to 2038 ± 70 µg/g. The proposed MIC method was considered suitable for quality control for chlorine determination in medicinal plants.
A method for As determination in sulfur-containing active pharmaceutical ingredients (SC-APIs) by direct solid sampling graphite furnace atomic absorption (DSS-GF AAS) was developed. The proposed ...method was successfully applied to three SC-APIs (hydrochlorothiazide, furosemide and sulfadiazine). Palladium was used as chemical modifier as well as hydrogen during the pyrolysis allowing the direct determination of As in the SC-APIs without interferences caused by gaseous sulfur species. Sample masses (hydrochlorothiazide) from 0.4 to 3 mg were used and calibration with aqueous standard solutions was feasible. The limit of quantification was 0.033 mg g-1 and the calibration ranged from 0.1 to 1.6 ng As. Recoveries for As solutions added directly to the solid samples were between 95 and 103%, showing a good accuracy. The method validation highlighted its robustness, since variation in pyrolysis and atomization temperatures, as well as in Pd and sample masses, did not change significantly the results. Additional experiments showed that this method can be applied to other SC-APIs (as e.g., furosemide and sulfadiazine). Arsenic concentration in hydrochlorothiazide samples ranged from 0.13 to 0.48 mg g-1, while in furosemide and sulfadiazine samples it was from 0.49 and 0.54 mg g-1, respectively. The use of DSS-GF AAS does not require previous sample digestion and As could be directly determined in the solid samples providing some advantages, as lower risks of contamination and analyte losses, good accuracy and limits of quantification.
A method based on microwave-induced combustion (MIC) was applied for medicinal plants digestion allowing further chlorine determination by potentiometry using ion-selective electrode (ISE). Sample ...masses ranging from 500 to 1000 mg were evaluated for MIC digestion. Water and 10, 25, 50, and 100 mmol/L NH4OH were investigated as absorbing solutions. The accuracy of the proposed method was evaluated by using certified reference materials (CRMs), by recovery tests (500 µg/g), and also by comparison with the results obtained by inductively coupled plasma optical emission spectrometry (ICP-OES) after microwave-assisted alkaline extraction (MAE). Using water or NH4OH solutions (10 to 100 mmol/L), recoveries close to 100% and relative standard deviation lower than 5% were obtained. Results were in agreement with CRMs values (better than 95%) and also with those values obtained by using the MAE method. The main advantage of the proposed method was the complete combustion of high sample mass (1000 mg) resulting in low quantification limit (12.5 µg/g) and chlorine determination at low concentration by ISE. Another advantage of the proposed method was the high chlorine stability in digests (up to 30 days of storage) even using water as absorbing solution, which is in agreement with green analytical chemistry recommendations. Finally, the proposed MIC method was applied for commercial medicinal plants and the chlorine concentration was in the range of 59.4 ± 1.4 to 2038 ± 70 µg/g. The proposed MIC method was considered suitable for quality control for chlorine determination in medicinal plants.
A method based on microwave-induced combustion (MIC) was applied for medicinal plants digestion allowing further chlorine determination by potentiometry using ion-selective electrode (ISE). Sample ...masses ranging from 500 to 1000 mg were evaluated for MIC digestion. Water and 10, 25, 50, and 100 mmol/L NH4OH were investigated as absorbing solutions. The accuracy of the proposed method was evaluated by using certified reference materials (CRMs), by recovery tests (500 µg/g), and also by comparison with the results obtained by inductively coupled plasma optical emission spectrometry (ICP-OES) after microwave-assisted alkaline extraction (MAE). Using water or NH4OH solutions (10 to 100 mmol/L), recoveries close to 100% and relative standard deviation lower than 5% were obtained. Results were in agreement with CRMs values (better than 95%) and also with those values obtained by using the MAE method. The main advantage of the proposed method was the complete combustion of high sample mass (1000 mg) resulting in low quantification limit (12.5 µg/g) and chlorine determination at low concentration by ISE. Another advantage of the proposed method was the high chlorine stability in digests (up to 30 days of storage) even using water as absorbing solution, which is in agreement with green analytical chemistry recommendations. Finally, the proposed MIC method was applied for commercial medicinal plants and the chlorine concentration was in the range of 59.4 ± 1.4 to 2038 ± 70 µg/g. The proposed MIC method was considered suitable for quality control for chlorine determination in medicinal plants.
A method based on microwave-induced combustion (MIC) was applied for medicinal plants digestion allowing further chlorine determination by potentiometry using ion-selective electrode (ISE). Sample ...masses ranging from 500 to 1000 mg were evaluated for MIC digestion. Water and 10, 25, 50, and 100 mmol/L NH4OH were investigated as absorbing solutions. The accuracy of the proposed method was evaluated by using certified reference materials (CRMs), by recovery tests (500 µg/g), and also by comparison with the results obtained by inductively coupled plasma optical emission spectrometry (ICP-OES) after microwave-assisted alkaline extraction (MAE). Using water or NH4OH solutions (10 to 100 mmol/L), recoveries close to 100% and relative standard deviation lower than 5% were obtained. Results were in agreement with CRMs values (better than 95%) and also with those values obtained by using the MAE method. The main advantage of the proposed method was the complete combustion of high sample mass (1000 mg) resulting in low quantification limit (12.5 µg/g) and chlorine determination at low concentration by ISE. Another advantage of the proposed method was the high chlorine stability in digests (up to 30 days of storage) even using water as absorbing solution, which is in agreement with green analytical chemistry recommendations. Finally, the proposed MIC method was applied for commercial medicinal plants and the chlorine concentration was in the range of 59.4 ± 1.4 to 2038 ± 70 µg/g. The proposed MIC method was considered suitable for quality control for chlorine determination in medicinal plants.
A method based on microwave-induced combustion (MIC) was applied for medicinal plants digestion allowing further chlorine determination by potentiometry using ion-selective electrode (ISE). Sample ...masses ranging from 500 to 1000 mg were evaluated for MIC digestion. Water and 10, 25, 50, and 100 mmol/L NH4OH were investigated as absorbing solutions. The accuracy of the proposed method was evaluated by using certified reference materials (CRMs), by recovery tests (500 µg/g), and also by comparison with the results obtained by inductively coupled plasma optical emission spectrometry (ICP-OES) after microwave-assisted alkaline extraction (MAE). Using water or NH4OH solutions (10 to 100 mmol/L), recoveries close to 100% and relative standard deviation lower than 5% were obtained. Results were in agreement with CRMs values (better than 95%) and also with those values obtained by using the MAE method. The main advantage of the proposed method was the complete combustion of high sample mass (1000 mg) resulting in low quantification limit (12.5 µg/g) and chlorine determination at low concentration by ISE. Another advantage of the proposed method was the high chlorine stability in digests (up to 30 days of storage) even using water as absorbing solution, which is in agreement with green analytical chemistry recommendations. Finally, the proposed MIC method was applied for commercial medicinal plants and the chlorine concentration was in the range of 59.4 ± 1.4 to 2038 ± 70 µg/g. The proposed MIC method was considered suitable for quality control for chlorine determination in medicinal plants.
A method for As determination in sulfur-containing active pharmaceutical ingredients (SC-APIs) by direct solid sampling graphite furnace atomic absorption (DSS-GF AAS) was developed. The proposed ...method was successfully applied to three SC-APIs (hydrochlorothiazide, furosemide and sulfadiazine). Palladium was used as chemical modifier as well as hydrogen during the pyrolysis allowing the direct determination of As in the SC-APIs without interferences caused by gaseous sulfur species. Sample masses (hydrochlorothiazide) from 0.4 to 3 mg were used and calibration with aqueous standard solutions was feasible. The limit of quantification was 0.033 mg g-1 and the calibration ranged from 0.1 to 1.6 ng As. Recoveries for As solutions added directly to the solid samples were between 95 and 103%, showing a good accuracy. The method validation highlighted its robustness, since variation in pyrolysis and atomization temperatures, as well as in Pd and sample masses, did not change significantly the results. Additional experiments showed that this method can be applied to other SC-APIs (as e.g., furosemide and sulfadiazine). Arsenic concentration in hydrochlorothiazide samples ranged from 0.13 to 0.48 mg g-1, while in furosemide and sulfadiazine samples it was from 0.49 and 0.54 mg g-1, respectively. The use of DSS-GF AAS does not require previous sample digestion and As could be directly determined in the solid samples providing some advantages, as lower risks of contamination and analyte losses, good accuracy and limits of quantification.
A method for As determination in sulfur-containing active pharmaceutical ingredients (SC-APIs) by direct solid sampling graphite furnace atomic absorption (DSS-GF AAS) was developed. The proposed ...method was successfully applied to three SC-APIs (hydrochlorothiazide, furosemide and sulfadiazine). Palladium was used as chemical modifier as well as hydrogen during the pyrolysis allowing the direct determination of As in the SC-APIs without interferences caused by gaseous sulfur species. Sample masses (hydrochlorothiazide) from 0.4 to 3 mg were used and calibration with aqueous standard solutions was feasible. The limit of quantification was 0.033 mg g-1 and the calibration ranged from 0.1 to 1.6 ng As. Recoveries for As solutions added directly to the solid samples were between 95 and 103%, showing a good accuracy. The method validation highlighted its robustness, since variation in pyrolysis and atomization temperatures, as well as in Pd and sample masses, did not change significantly the results. Additional experiments showed that this method can be applied to other SC-APIs (as e.g., furosemide and sulfadiazine). Arsenic concentration in hydrochlorothiazide samples ranged from 0.13 to 0.48 mg g-1, while in furosemide and sulfadiazine samples it was from 0.49 and 0.54 mg g-1, respectively. The use of DSS-GF AAS does not require previous sample digestion and As could be directly determined in the solid samples providing some advantages, as lower risks of contamination and analyte losses, good accuracy and limits of quantification.
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