Browsing by Author "Martins, Joana"
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- Analysis of six fungicides and one acaricide in still and fortified wines using solid-phase microextraction-gas chromatography/tandem mass spectrometryPublication . Martins, Joana; Esteves, Cristina; Limpo-Faria, Ana; Barros, Paulo; Ribeiro, Natália; Simões, Tomás; Correia, Manuela; Delerue-Matos, CristinaA multiresidue gas chromatographic method for the determination of six fungicides (captan, chlorthalonil, folpet, iprodione, procymidone and vinclozolin) and one acaricide (dicofol) in still and fortified wines was developed. Solid-phase microextraction (SPME) was chosen for the extraction of the compounds from the studied matrices and tandem mass spectrometry (MS/MS) detection was used. The extraction consists in a solvent free and automated procedure and the detection is highly sensitive and selective. Good linearity was obtained with correlation coefficients of regression (R2) > 0.99 for all the compounds. Satisfactory results of repeatability and intermediate precision were obtained for most of the analytes (RSD < 20%). Recoveries from spiked wine ranged from 80.1% to 112.0%. Limits of quantification (LOQs) were considerably below the proposedmaximumresidue limits (MRLs) for these compounds in grapes and below the suggested limits for wine (MRLs/10), with the exception of captan.
- Cyanobacterial diversity held in microbial biological resource centers as a biotechnological asset: the case study of the newly established LEGE culture collectionPublication . Ramos, Vitor; Morais, João; Castelo-Branco, Raquel; Pinheiro, Ângela; Martins, Joana; Regueiras, Ana; Pereira, Ana L.; Lopes, Viviana R.; Frazão, Bárbara; Gomes, Dina; Moreira, Cristiana; Costa, Maria Sofia; Brûle, Sébastien; Faustino, Silvia; Martins, Rosario; Saker, Martin; Osswald, Joana; Leão, Pedro N.; Vasconcelos, Vitor M.Cyanobacteria are a well-known source of bioproducts which renders culturable strains a valuable resource for biotechnology purposes. We describe here the establishment of a cyanobacterial culture collection (CC) and present the first version of the strain catalog and its online database (http://lege.ciimar.up.pt/). The LEGE CC holds 386 strains, mainly collected in coastal (48%), estuarine (11%), and fresh (34%) water bodies, for the most part from Portugal (84%). By following the most recent taxonomic classification, LEGE CC strains were classified into at least 46 genera from six orders (41% belong to the Synechococcales), several of them are unique among the phylogenetic diversity of the cyanobacteria. For all strains, primary data were obtained and secondary data were surveyed and reviewed, which can be reached through the strain sheets either in the catalog or in the online database. An overview on the notable biodiversity of LEGE CC strains is showcased, including a searchable phylogenetic tree and images for all strains. With this work, 80% of the LEGE CC strains have now their 16S rRNA gene sequences deposited in GenBank. Also, based in primary data, it is demonstrated that several LEGE CC strains are a promising source of extracellular polymeric substances (EPS). Through a review of previously published data, it is exposed that LEGE CC strains have the potential or actual capacity to produce a variety of biotechnologically interesting compounds, including common cyanotoxins or unprecedented bioactive molecules. Phylogenetic diversity of LEGE CC strains does not entirely reflect chemodiversity. Further bioprospecting should, therefore, account for strain specificity of the valuable cyanobacterial holdings of LEGE CC.
- Desenvolvimento de metodologias analíticas para a determinação de resíduos de pesticidas em Vinhos do Douro e Vinhos do PortoPublication . Martins, Joana; Correia, Maria Manuela Barbosa; Delerue-Matos, Cristina Maria FernandesA produção de vinho é uma actividade de elevada importância ao nível económico, ambiental e social. Como tal, a protecção da vinha e/ou da uva através da utilização de pesticidas assume um papel fundamental nesta actividade, permitindo um aumento no rendimento da produção. No entanto, a transferência destes compostos da uva para o vinho é inevitável, ocorrendo, na maioria dos casos, em quantidades reduzidas. Apesar de, geralmente, a quantidade de pesticidas que pode ser transferida para o vinho não apresentar problemas relevantes para a saúde pública, o desenvolvimento de metodologias que permitam garantir um controlo rigoroso da qualidade do vinho é de elevada importância. O controlo deste produto, assim como de qualquer produto alimentar, não deve ser de certa forma virtual, levando a uma desconfiança crescente do consumidor. Ao longo deste trabalho foram desenvolvidos dois métodos para a determinação de pesticidas em diferentes tipos de vinhos, por SPME-GC-MS/MS. O primeiro método desenvolvido visa a determinação de 8 pesticidas organofosforados e o segundo método permite a determinação de 7 pesticidas, 4 organoclorados e 3 dicarboximidas. Foram estudadas quatro matrizes diferentes: vinho branco do Douro, vinho tinto do Douro, vinho branco do Porto e vinho tinto do Porto. As metodologias adoptadas permitiram a obtenção de bons resultados, apesar das condições adoptadas não serem as mais vantajosas para alguns dos compostos estudados. Dada a complexidade das matrizes, a detecção por espectrometria de massa mostrou ser fundamental para a identificação inequívoca de cada um dos pesticidas. Verificaram-se, de um modo geral, bons resultados ao nível da linearidade, para as gamas de concentrações escolhidas, para os dois métodos. Obtiveram-se também bons resultados para os limites de detecção e quantificação, cujos valores se situam abaixo dos limites máximos de resíduos para as uvas, impostos pela regulamentação europeia, para a maioria dos compostos. No caso dos organofosforados, os limites de detecção variam entre 0,05 μg/L e 13,00 μg/L para os pesticidas clorpirifos-metilo e metidatião, respectivamente. Os limites de quantificação variam entre 0,18 μg/L e 43,32 μg/L, também para os pesticidas clorpirifos-metilo e metidatião. No que se refere ao método para os pesticidas organoclorados e dicarboximidas, foram calculados vários limites de detecção para cada composto, em cada matriz estudada, a partir das rectas de calibração diárias, resultando num conjunto de valores com variações significativas entre cada um, para o mesmo pesticida e na mesma matriz. No entanto, apenas os limites de quantificação foram validados, recorrendo-se aos estudos de repetibilidade e precisão intermédia. Obtiveram-se os seguintes limites de quantificação: captana 52,10 μg/L; clortalonil 20,95 μg/L; dicofol 4,37 μg/L; folpete 93,60 μg/L; iprodiona 274,70 μg/L; procimidona 76,04 μg/L e vinclozolina 10,03 μg/L. Os pesticidas metidatião e captana apresentam-se como os compostos mais problemáticos, uma vez que os limites de quantificação obtidos não permitem a garantia do cumprimento dos limites máximos de resíduos regulamentados. Demonstra-se também que, apesar do efeito de matriz ser significativo na determinação de todos os compostos analisados, o mesmo pode ser atenuado, procedendo-se às calibrações nas respectivas matrizes. Observaram-se variações significativas ao nível da resposta do equipamento ao longo do tempo, quer pela alteração das condições operatórias, quer pela decomposição de alguns compostos ao longo do tempo. Este efeito, evidenciado nos estudos das precisões intermédias e repetibilidades, levou à adopção de um método de validação diferente para a determinação de pesticidas organoclorados e dicarboximidas, recorrendo-se então a calibrações diárias e sequências de trabalho mais pequenas.
- Determination of 24 pesticide residues in fortified wines by solid-phase microextraction and gas chromatography tandem mass spectrometryPublication . Martins, Joana; Esteves, Cristina; Simões, Tomás; Correia, Manuela; Delerue-Matos, CristinaThe present work describes a solid-phase microextraction (SPME) gas chromatography_tandem mass spectrometry (MS/MS) method to quantify 24 pesticides in fortified white wine and fortified red wine. In this study “fortified wine” refers to a wine in which fermentation is arrested before completion by alcohol distillate addition, allowing sugar and alcoholic contents to be higher (around 80-100 g/L total sugars and 19-22% alcohol strength (v/v)). The analytical method showed good linearity, presenting correlation coefficients (R2) ≥ 0.989 for all compounds. Limits of detection (LOD) and quantitation (LOQ) in the ranges of 0.05-72.35 and 0.16-219.23 μg/L, respectively, were obtained. LOQs are below the maximum residue levels (MRL) set by European Regulation for grapes. The proposed method was applied to 17 commercial fortified wines. The analyzed pesticides were not detected in the wines tested.
- Multiresidue method for the determination of organophosphorus pesticides in still wine and fortified wine using solid-phase microextraction and gas chromatography – Tandem mass spectrometryPublication . Martins, Joana; Esteves, Cristina; Limpo-Faria, Ana; Barros, Paulo; Ribeiro, Natália; Simões, Tomás; Correia, Manuela; Delerue-Matos, CristinaA SPME-GC-MS/MS method for the determination of eight organophosphorus pesticides (azinphos-methyl, chlorpyriphos, chlorpyriphos-methyl, diazinon, fenitrothion, fenthion, malathion, and methidathion) in still and fortified wine was developed. The extraction procedure is simple, solvent free, and without any sample pretreatment. Limits of detection (LOD) and quantitation (LOQ) values in the range 0.1–14.3 lg/L and 0.2–43.3 lg/L, respectively, were obtained. The LOQ values are below the maximum residue levels (MRLs) established by European Regulation for grapes, with the exception of methidathion. Coefficients of correlation (R2) higher than 0.99 were obtained for the majority of the pesticides, in all different wines analyzed.
- Presence of microcystis sp. and microcystins in alqueva reservoirs assessed by chemical and molecular methodsPublication . Azevedo, Tomé; Azevedo, Joana; Martins, Joana; Freitas, Marisa; Vasconcelos, Vitor; Campos, AlexandreThe Alqueva reservoir, located in the Alentejo region, in the south of Portugal, is considered the largest artificial lake in Europe. It has been in operation since 2002, and it is used to produce energy and supply water for agriculture and to the populations in this region of Portugal. The water distribution system, starting from the main reservoir, includes 19 reservoirs of smaller capacity and a network of waterways totaling 382 km in length. Furthermore, the occurrence of cyanobacteria in water reservoirs has been recognized as an environmental concern due to the potential presence of their related toxins that can cause severe health effects. This work aimed to monitor the presence of cyanobacteria and the commonly associated cyanotoxin microcystin (MC) in three reservoirs belonging to the Alqueva water system, namely São Pedro, Magra, and Pisão, located in the district of Beja. These reservoirs were selected considering the historical data of phytoplankton provided by EDIA, the entity in charge of the management of this infrastructure. The field work was carried out in July, August, and September, the months with the highest risk of outgrowth of cyanobacteria, in the year 2020. Two or three samples of water (5 L) were collected in different locations of the reservoirs, once per month, by boat. Samples were collected at different depths in the photic zone using a Van Dorn bottle and pooled. The water samples were then processed in the laboratory. Molecular biology techniques were used to detect the presence of cyanobacteria (16S rRNA) and MC-related genes. Moreover, chemical analysis techniques based on liquid chromatography and mass spectrometry (MS) were used to identify and quantify MCs. The results revealed the presence of MCs in the three reservoirs in the three months monitored. Concentrations of this toxin varied between 0.01 µg/L and 0.1 µg/L, with São Pedro being the reservoir displaying the highest concentrations of MCs in all of the months monitored. These results are consistent with the molecular study based on the analysis of Microcystis sp. 16 rRNA and MC biosynthetic genes (mcya–mcyG), suggesting the presence of putative toxic Microcystis sp. strains in the three reservoirs. Despite the low concentrations of MCs detected in these reservoirs, their recurrent presence in Alqueva waters serve as a reminder of the need to monitor cyanobacteria and cyanotoxins on a regular basis.