| Name: | Description: | Size: | Format: | |
|---|---|---|---|---|
| 2.28 MB | Adobe PDF |
Authors
Advisor(s)
Abstract(s)
A 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.
Wine production represents a very important activity in economic, environmental and social terms. Thus, the use of pesticides for vineyard and/or grape protection is a fundamental contribution to this activity, allowing an increase on productivity. However, the transfer of these compounds from the grape to the wine is inevitable, occurring, in the most of the cases, in low quantities. Although the pesticide amount that can be transferred to the wine does not present a risk for the public health, the development of methodologies allowing the guarantee of a rigorous control of the wine quality is very important. The control of this product, as well as other food products should not occur in a virtual way, increasing the mistrust of the consumers. During this work, two methodologies for the pesticides determination in different wines, by SPME-GC-MS/MS were developed. The first methodology allowed the determination of 8 organophosphorus pesticides and the second methodology enabled the determination of 7 pesticides: 4 organochlorines and 3 dicarboximides. Four different matrixes were studied: Douro white wine, Douro red wine, Porto white wine and Porto red wine. The methodologies adopted allowed to achieve good results, despite of the conditions adopted were not the most advantageous for some of the studied compounds. Mass spectrometry shows to be a fundamental instrument for the unequivocal identification of each studied pesticide, in the presence of such complex matrixes. Good linearity was achieved, in most of the cases, for the concentration ranges adopted, in all matrixes and for both methodologies. Acceptable limits of detection and quantification were obtained, the majority of them above of the limits established by EC Regulation for grapes. For the organophosphorus, the lowest limit of detection value obtained was 0,05 μg/L for chlorpyriphos-methyl, and the highest value was 13,00 μg/L, for methidathion. The lowest limit of quantification value obtained was 0,18 μg/L and the highest value was 43,32 μg/L, for chlorpyriphos-methyl and for methidathion, respectively. As regards to the methodology for the determination of organochlorine and dicarboximide pesticides, several limits of detection were calculated for each compound, in all matrixes, from the calibration curves obtained dairy, resulting in a set of values with a expressive difference between them, for each compound, in the same matrix. However, only the limits of quantification were validated, trough the repeatability and intermediate precision studies. The following limits of quantification were obtained: captan 52,10 μg/L; chlorotalonil 20,95 μg/L; dicofol 4,37 μg/L; folpet 93,60 μg/L; iprodione 274,70 μg/L; procymidone 76,04 μg/L e vinclozolin 10,03 μg/L. Methidathion and captan were the most problematic pesticides due to their high limits of quantification, which do not allow the control of the limits of residues as established by the regulation. The matrix effect on the determination of all compounds is very expressive. However it can be minimized with calibrations in the respective matrixes. The equipment response presents considerable variations due to the continuing modification of the equipment conditions and /or to the decay of some compounds. This effect, shown by the repeatability and intermediate precision studies, contributed for the adoption of a different method of validation for the determination of organochlorine and dicarboximide pesticides, trough dairy calibrations and shorter sequences of work.
Wine production represents a very important activity in economic, environmental and social terms. Thus, the use of pesticides for vineyard and/or grape protection is a fundamental contribution to this activity, allowing an increase on productivity. However, the transfer of these compounds from the grape to the wine is inevitable, occurring, in the most of the cases, in low quantities. Although the pesticide amount that can be transferred to the wine does not present a risk for the public health, the development of methodologies allowing the guarantee of a rigorous control of the wine quality is very important. The control of this product, as well as other food products should not occur in a virtual way, increasing the mistrust of the consumers. During this work, two methodologies for the pesticides determination in different wines, by SPME-GC-MS/MS were developed. The first methodology allowed the determination of 8 organophosphorus pesticides and the second methodology enabled the determination of 7 pesticides: 4 organochlorines and 3 dicarboximides. Four different matrixes were studied: Douro white wine, Douro red wine, Porto white wine and Porto red wine. The methodologies adopted allowed to achieve good results, despite of the conditions adopted were not the most advantageous for some of the studied compounds. Mass spectrometry shows to be a fundamental instrument for the unequivocal identification of each studied pesticide, in the presence of such complex matrixes. Good linearity was achieved, in most of the cases, for the concentration ranges adopted, in all matrixes and for both methodologies. Acceptable limits of detection and quantification were obtained, the majority of them above of the limits established by EC Regulation for grapes. For the organophosphorus, the lowest limit of detection value obtained was 0,05 μg/L for chlorpyriphos-methyl, and the highest value was 13,00 μg/L, for methidathion. The lowest limit of quantification value obtained was 0,18 μg/L and the highest value was 43,32 μg/L, for chlorpyriphos-methyl and for methidathion, respectively. As regards to the methodology for the determination of organochlorine and dicarboximide pesticides, several limits of detection were calculated for each compound, in all matrixes, from the calibration curves obtained dairy, resulting in a set of values with a expressive difference between them, for each compound, in the same matrix. However, only the limits of quantification were validated, trough the repeatability and intermediate precision studies. The following limits of quantification were obtained: captan 52,10 μg/L; chlorotalonil 20,95 μg/L; dicofol 4,37 μg/L; folpet 93,60 μg/L; iprodione 274,70 μg/L; procymidone 76,04 μg/L e vinclozolin 10,03 μg/L. Methidathion and captan were the most problematic pesticides due to their high limits of quantification, which do not allow the control of the limits of residues as established by the regulation. The matrix effect on the determination of all compounds is very expressive. However it can be minimized with calibrations in the respective matrixes. The equipment response presents considerable variations due to the continuing modification of the equipment conditions and /or to the decay of some compounds. This effect, shown by the repeatability and intermediate precision studies, contributed for the adoption of a different method of validation for the determination of organochlorine and dicarboximide pesticides, trough dairy calibrations and shorter sequences of work.
Description
Keywords
Pesticidas Vinhos SPME GC-MS/MS Pesticides Wines
Citation
Publisher
Instituto Politécnico do Porto. Instituto Superior de Engenharia do Porto