Browsing by Author "Alves, Arminda"
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- Adsorption behavior of α-cypermethrin on cork and activated carbonPublication . Domingues, Valentina F.; Priolo, Giuseppe; Alves, Arminda; Cabral, Miguel; Delerue-Matos, CristinaStudies were undertaken to determine the adsorption behavior of α-cypermethrin [R)-α-cyano-3-phenoxybenzyl(1S)-cis- 3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate, and (S)-α-cyano-3-phenoxybenzyl (1R)-cis-3-(2,2-dichlorovinyl)-2,2- dimethylcyclopropanecarboxylate] in solutions on granules of cork and activated carbon (GAC). The adsorption studies were carried out using a batch equilibrium technique. A gas chromatograph with an electron capture detector (GC-ECD) was used to analyze α-cypermethrin after solid phase extraction with C18 disks. Physical properties including real density, pore volume, surface area and pore diameter of cork were evaluated by mercury porosimetry. Characterization of cork particles showed variations thereby indicating the highly heterogeneous structure of the material. The average surface area of cork particles was lower than that of GAC. Kinetics adsorption studies allowed the determination of the equilibrium time—24 hours for both cork (1–2 mm and 3–4 mm) and GAC. For the studied α-cypermethrin concentration range, GAC revealed to be a better sorbent. However, adsorption parameters for equilibrium concentrations, obtained through the Langmuir and Freundlich models, showed that granulated cork 1–2 mm have the maximum amount of adsorbed α-cypermethrin (qm) (303 μg/g); followed by GAC (186 μg/g) and cork 3-4 mm (136 μg/g). The standard deviation (SD) values, demonstrate that Freundlich model better describes the α-cypermethrin adsorption phenomena on GAC, while α-cypermethrin adsorption on cork (1-2 mm and 3-4 mm) is better described by the Langmuir. In view of the adsorption results obtained in this study it appears that granulated cork may be a better and a cheaper alternative to GAC for removing α-cypermethrin from water.
- Analysis of PCBs in soils and sediments by microwave-assisted extraction, headspace-SPME and high resolution gas chromatography with ion-trap tandem mass spectrometryPublication . Herbert, Paulo; Morais, Simone; Paíga, Paula; Alves, Arminda; Santos, LúciaA procedure for the determination of seven indicator PCBs in soils and sediments using microwave-assisted extraction (MAE) and headspace solid-phase microextraction (HS-SPME) prior to GC-MS/MS is described. Optimization of the HS-SPME was carried out for the most important parameters such as extraction time, sample volume and temperature. The adopted methodology has reduced consumption of organic solvents and analysis runtime. Under the optimized conditions, the method detection limit ranged from 0.6 to 1 ng/g when 5 g of sample was extracted, the precision on real samples ranged from 4 to 21% and the recovery from 69 to 104%. The proposed method, which included the analysis of a certified reference material in its validation procedure, can be extended to several other PCBs and used in the monitoring of soil or sediments for the presence of PCBs.
- Anti-Angiogenic Properties of Cafestol and Kahweol Palmitate Diterpene EstersPublication . Moeenfard, Marzieh; Cortez, Alice; Machado, Vera; Costa, Raquel; Luís, Carla; Coelho, Pedro; Soares, Raquel; Alves, Arminda; Borges, Nuno; Santos, AlejandroEpidemiological studies support the association of coffee-specific diterpenes, with various beneficial health effects. Although anti-antiangiogenic properties of free cafestol and kahweol have been recently described, available data regarding their esterified form, in particular palmitate esters as the main diterpene esters present in coffee, are still rare. Given that angiogenesis plays an important role in many pathological conditions, including cancer growth and metastasis, this study aimed to assess and compare the potential anti-angiogenic effects of cafestol palmitate (CP) and kahweol palmitate (KP) in an in vitro angiogenesis model. According to our findings, both compounds inhibited angiogenesis steps on human microvascular endothelial cells (HMVECs), although a more significant effect was observed for KP. Compared to control, HMVECs viability decreased in a dose-dependent manner upon incubation either with CP or KP. Concentrations of 75 and 100 μM of each compound were cytotoxic. Cell proliferation was also dramatically reduced by both diterpene esters at 50 μM, although KP had a stronger inhibitory effect. However, CP and KP did not induce apoptosis on HMVECs. Both compounds reduced cell migration, but this effect was only statistically significant after KP incubation. Inhibition of VEGFR2 expression and its downstream effector Akt, but not Erk, was also observed in CP- and KP-treated HMVECs. These findings were confirmed using ELISA assay for phosphorylated (active) VEGFR-2. Taken together, these data indicate that both CP and KP can be considered potent compounds against angiogenesis-dependent disorders. Our findings further indicate that KP exerts more potent anti-angiogenic effects than CP, in most of assays.
- Determination of carbamate and urea pesticide residues in fresh vegetables using microwave-assisted extraction and liquid chromatographyPublication . Paíga, Paula; Morais, Simone; Correia, Manuela; Delerue-Matos, Cristina; Alves, ArmindaAn analytical multiresidue method for the simultaneous determination of seven pesticides in fresh vegetable samples, namely, courgette (Cucurbita pepo), cucumber (Cucumis sativus), lettuce (Lactuca sativa, Romaine and Iceberg varieties) and peppers (Capsicum sp.) is described. The procedure, based on microwave-assisted extraction (MAE) and analysis by liquid chromatography– photodiode array (LC–PDA) detection was applied to four carbamates (carbofuran, carbaryl, chlorpropham and EPTC) and three urea pesticides (monolinuron, metobromuron and linuron). Extraction solvent and the addition of anhydrous sodium sulphate to fresh vegetable homogenate before MAE were the parameters optimised for each commodity. Recovery studies were performed using spiked samples in the range 250–403 µgkg- 1 in each pesticide. The pesticide residues were extracted using 20mL acetonitrile at 60 ºC, for 10 min. Acceptable recoveries and RSDs were attained (overall average recovery of 77.2% and RSDs are lower than 11%). Detection limits ranged between 5.8 µgkg- 1 for carbaryl to 12.3 µgkg- 1 for carbofuran. The analytical protocol was applied for quality control of 41 fresh vegetable samples bought in Oporto Metropolitan Area (North Portugal). None of the samples contained any detectable amounts of the studied compounds.
- Development and validation of a novel method for the analysis of chlorinated pesticides in soils using microwave-assisted extraction–headspace solid phase microextraction and gas chromatography–tandem mass spectrometryPublication . Herbert, Paulo; Morais, Simone; Paíga, Paula; Alves, Arminda; Santos, LúciaA new procedure for determining eleven organochlorine pesticides in soils using microwave-assisted extraction (MAE) and headspace solid phase microextraction (HS-SPME) is described. The studied pesticides consisted of mirex, α- and γ-chlordane, p,p’-DDT, heptachlor, heptachlor epoxide isomer A, γ-hexachlorocyclohexane, dieldrin, endrin, aldrine and hexachlorobenzene. The HS-SPME was optimized for the most important parameters such as extraction time, sample volume and temperature. The present analytical procedure requires a reduced volume of organic solvents and avoids the need for extract clean-up steps. For optimized conditions the limits of detection for the method ranged from 0.02 to 3.6 ng/g, intermediate precision ranged from 14 to 36% (as CV%), and the recovery from 8 up to 51%. The proposed methodology can be used in the rapid screening of soil for the presence of the selected pesticides, and was applied to landfill soil samples.
- Fast screening procedure for antibiotics in wastewaters by direct HPLC-DAD analysisPublication . Teixeira, Salomé; Delerue-Matos, Cristina; Alves, Arminda; Santos, LúciaGrowing concern about the contamination of wastewaters by antibiotics demands fast but sensitive analytical methodologies, for the screening of a large number of samples. The purpose of this work was to develop a simple methodology, using direct injection of the samples, by HPLC with diode array detection (DAD), for a multiresidue analysis of five antibiotics of different classes. Wastewater from an urban water treatment plant was selected as a model to study possible coelution of interfering compounds. The linearity interval ranged from 40 to 400 µg/L for amoxicillin (Amox), metronidazole (Metro), cefazolin (Cefa), and chloramphenicol (Chloram) and from 20 to 200 µg/L for sulfamethoxazole (Sulfa), with LODs lower than 14 µg/L. Repeatability, expressed by the CV of six repeated injections, ranged from 1 to 8%, while the intermediate precision varied between 2 and 11%. The recovery ranged from 90 to 109%. This method enables the fast screening of a large number of samples, with an expanded uncertainty in the 1–22% range. The advantage of the proposed method is to significantly reduce the number of samples to be analyzed by more complex methods.
- A multiresidue method for the analysis of carbamate and urea pesticides from soils by microwave-assisted extraction and liquid chromatography with photodiode array detectionPublication . Paíga, Paula; Morais, Simone; Correia, Manuela; Alves, Arminda; Delerue-Matos, CristinaA multiresidue approach using microwave-assisted extraction and liquid chromatography with photodiode array detection was investigated for the determination of butylate, carbaryl, carbofuran, chlorpropham, ethiofencarb, linuron,metobromuron, and monolinuron in soils. The critical parameters of the developed methodology were studied. Method validation was performed by analyzing freshly and aged spiked soil samples. The recoveries and relative standard deviations reached using the optimized conditions were between 77.0 ± 0.46% and 120 ± 2.9% except for ethiofencarb (46.4 ± 4.4% to 105 ± 1.6%) and butylate (22.1 ± 7.6% to 49.2 ± 11%). Soil samples from five locations of Portugal were analysed.
- Risk of children’s dermal exposure to Galaxolide through personal care productsPublication . Correia, Patrícia; Cruz, Agostinho; Santos, Lúcia; Alves, ArmindaGalaxolide is the most used fragrance since the early 1990s, and it has been largely detected in environmental and biological matrices. This polycyclic musk is present in almost all of our daily products, so the risk of human exposure is substantial, as it had been proved by its detection in human tissues and fluids. Due to the lack of information about the concentrations found in consumer products, monitoring data is needed for exposure assessment purposes. Dermal contact, mostly by personal care products, seems to be the major route of human exposure to galaxolide, and, due to the immaturity of young children’s skin, exposure consequences can be worse in this population. The main objective of this study was to evaluate galaxolide levels in personal care products used by children of Oporto (Portugal), aged 0–5 years, and relate it with consumer habits. Consumer patterns were obtained through 250 questionnaires to caregivers of Oporto children. The 79 most used products were extracted by a dispersive solid phase extraction methodology known as QuEChERS and galaxolide was determined by High Performance Liquid Chromatography (HPLC) with fluorescence detection. The concentrations ranged between 0.001 ± 0.001 mg·kg−1, on a baby wipe, and 300.480 ± 8.819 mg·kg−1, on glycerin soap, which may correspond to an estimated daily dermal exposure of 277.10 ± 0.02 µg·day−1 on the population of Oporto children. This value is in the range of the results observed for adults, although no information of toxicological risk for children is available.
- Screening of carbamates and ureas in fresh and processed tomato samples using micowave-assisted extraction and liquid chromatographyPublication . Paíga, Paula; Morais, Simone; Correia, Manuela; Alves, Arminda; Delerue-Matos, CristinaAn analytical method, based on microwave-assisted extraction and liquid chromatography with diode array detection, for the determination of six carbamate and three urea pesticides in fresh and processed tomato samples is described. Significant parameters affecting extraction efficiency were optimized. Under optimum microwave-assisted extraction conditions (20mL acetonitrile, for 10 minutes, at 60º C), pesticides were extracted with recoveries ranging from 57.6 to 102% (RSDs<7%). Quantification limits between 6.5 and 39.6 µg=kg were obtained. A total number of 28 different fresh tomato samples and 6 processed tomato products were analysed. Confirmation of suspicious samples was performed by LC-MS.
- Screening of grapes and wine for azoxystrobin, kresoxim-methyl and trifloxystrobin fungicides by HPLC with diode array detectionPublication . Abreu, Susana; Correia, Manuela; Herbert, Paulo; Santos, Lúcia; Alves, ArmindaThe Quinone outside Inhibitors (QoI) are one of the most important and recent fungicide groups used in viticulture and also allowed by Integrated Pest Management. Azoxystrobin, kresoxim-methyl and trifloxystrobin are the main active ingredients for treating downy and powdery mildews that can be present in grapes and wines. In this paper, a method is reported for the analysis of these three QoI-fungicides in grapes and wine. After liquid–liquid extraction and a clean-up on commercial silica cartridges, analysis was by isocratic HPLC with diode array detection (DAD) with a run time of 13 min. Confirmation was by solid-phase micro-extraction (SPME), followed by GC/MS determination. The main validation parameters for the three compounds in grapes and wine were a limit of detection up to 0.073mg kg-1, a precision not exceeding 10.0% and an average recovery of 93% ±38.