Browsing by Author "Pinho, Olívia"
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- Analysis of Pesticides in Tomato Combining QuEChERS and Dispersive Liquid–Liquid Microextraction Followed by High-Performance Liquid ChromatographyPublication . Melo, Armindo; Mansilha, Catarina; Pinho, Olívia; Ferreira, Isabel M.P.L.V.O.A new sample preparation procedure combining QuEChERS and dispersive liquid–liquid microextraction (DLLME) was optimized for the determination at trace levels of 13 pesticides from different chemical families (i.e. 2,4-D, acetamiprid, bentazone, cymoxanil, deltamethrin, dicamba, diuron, foramsulfuron, mesotrione, metalaxyl- M, methomyl, pyraclostrobin and tembotrione) in tomato by high-performance liquid chromatography with diode array detection. Target pesticides from tomato samples were isolated by liquid partitioning with acetonitrile and salts and cleaned up by dispersive solid-phase extraction (d-SPE); the analytes were concentrated in trichloromethane by the DLLME procedure. The disperser solvent from DLLME was used at the same time as carrier of analytes form extraction in QuEChERS method. The main factors affecting sample cleanup by d-SPE in QuEChERS and DLLME yield were optimized by means of an experimental design.Under the optimum conditions, good linearity was obtained, the recoveries of pesticides in tomato samples at spiking levels between 0.01 and 1.00 mg/kg ranged from 86 to 116 % (for foramsulfuron and cymoxanil, respectively). Precision was within 15.0 % (RSD) except at the LQ for tembotrione, which was 17.4 %. Limits of quantification achieved (ranging from 0.0058 to 0.15 mg/kg) were below the maximum residue limits established by the European Union.
- Fast and Reliable Extraction of Polycyclic Aromatic Hydrocarbons from Grilled and Smoked Muscle FoodsPublication . Silva, Marta; Viegas, Olga; Melo, Armindo; Finteiro, Daniela; Pinho, Olívia; Ferreira, Isabel M. P. L. V. O.A fast and simple method for analysis of 14 PAHs in grilled and smoked muscle foods using acetonitrile based-extraction was validated. The optimum amounts of magnesium sulfate and sodium chloride that promoted phase separation of acetonitrile extract containing PAHs from water phase were selected by Central Composite Design. Matrix-matched calibration curves were constructed by adding different concentrations of PAHs and then subjected to extraction followed by HPLC with fluorescent detection. An excellent linearity for all compounds applying weighed least squares linear regression procedure was achieved. LODs and LOQs were lower than 0.12 and 0.39 ng g−1 respectively. Validation was done according to International Conference on Harmonization recommendations for 14 PAHs. The criteria for 4 EU marker PAHs (benz[a]anthracene, chrysene, benzo[b]fluoranthene and benzo[a]pyrene) established by European Comission Regulation No. 836/2011 was also accomplished. Repeatability and reproducibility were lower than 8 and 13.3%, and the most of recoveries fall in the range of 80–110% in different grilled and smoked muscle foods. The proposed method is a robust tool for determination of PAHs in grilled and smoked muscle foods, being easy to perform in short time.
- Monitoring pesticide residues in greenhouse tomato by combining acetonitrile-based extraction with dispersive liquid–liquid microextraction followed by gas-chromatography–mass spectrometryPublication . Melo, Armindo; C. Cunha, Sara; Mansilha, Catarina; Aguiar, Ana; Pinho, Olívia; Ferreira, Isabel M.P.L.V.O.A multiclass and multiresidue method for pesticide analysis in tomato was validated. Extraction and preconcentration of the pesticide residues from acetonitrile extracts was performed by using dispersive liquid–liquid microextraction (DLLME) technique, followed by gas chromatography–mass detection. DLLME was performed using carbon tetrachloride as extractive solvent and acetonitrile extract as dispersive solvent, in order to increase enrichment factor of the extraction procedure. Validation parameters indicated the suitability of the method for routine analyses of thirty pesticides in a large number of samples. In general, pesticide recoveries ranged between 70% and 110% and repeatability ranged between 1% and 20%. The proposed method was applied to the monitoring of pesticides in tomatoes grown during winter in greenhouses. Among the compounds considered in this work, cyprodinil was found in tomato at concentrations of 0.33 mg/kg, other pesticides like azoxystrobin, fenhexanid, tolyfluanid, k-cyhalothrin and trifloxystrobin were also detected, but, not quantified.
- Patterns of Street Food Purchase in Cities From Central AsiaPublication . Sousa, Sofia; Lança de Morais, Inês; Albuquerque, Gabriela; Gelormini, Marcello; Casal, Susana; Pinho, Olívia; Motta, Carla; Damasceno, Albertino; Moreira, Pedro; Breda, João; Lunet, Nuno; Padrão, PatríciaStreet food makes a significant contribution to the diet of many dwellers in low- and middle-income countries and its trade is a well-developed activity in the central Asian region. However, data on its purchase and nutritional value is still scarce. This study aimed to describe street food purchasing patterns in central Asia, according to time and place of purchase. A multicentre cross-sectional study was conducted in 2016/2017 in the main urban areas of four central Asian countries: Dushanbe (Tajikistan), Bishkek (Kyrgyzstan), Ashgabat (Turkmenistan) and Almaty (Kazakhstan). Street food markets (n = 34) and vending sites (n = 390) were selected by random and systematic sampling procedures. Data on the purchased foods and beverages were collected by direct observation. Time and geographic location of the purchases was registered, and their nutritional composition was estimated. A total of 714 customers, who bought 852 foods, were observed. Customers’ influx, buying rate and purchase of industrial food were higher in city centers compared to the outskirts (median: 4.0 vs. 2.0 customers/10min, p < 0.001; 5.0 vs. 2.0 food items/10min, p < 0.001; 36.2 vs. 28.7%, p = 0.004). Tea, coffee, bread and savory pastries were most frequently purchased in the early morning, bread, main dishes and savory pastries during lunchtime, and industrial products in the mid-morning and mid-afternoon periods. Energy and macronutrient density was highest at 11:00–12:00 and lowest at 09:00–10:00. Purchases were smaller but more energy-dense in city centers, and higher in saturated and trans-fat in the peripheries. This work provides an overview of the street food buying habits in these cities, which in turn reflect local food culture. These findings from the main urban areas of four low- and middle-income countries which are currently under nutrition transition can be useful when designing public health interventions customized to the specificities of these food environments and their customers.
- Simultaneous QuEChERS and DLLME extraction of pesticides in tomato samplesPublication . Melo, Armindo; Mansilha, Catarina; Pinho, Olívia; Ferreira, Isabel