Research Article Influence of Hydroxypropyl--Cyclodextrin on the Photostability of Fungicide Pyrimethanil Carlos Fernandes, 1,2 Igor Encarnação, 1,2 Alexandra Gaspar, 1,2 Jorge Garrido, 1,2 Fernanda Borges, 2 and E. Manuela Garrido 1,2 1 Departamento de Engenharia Qu´ ımica, Instituto Superior de Engenharia do Porto (ISEP), Instituto Polit´ ecnico do Porto, 4200-072 Porto, Portugal 2 CIQ/Departamento de Qu´ ımica e Bioqu´ ımica, Faculdade de Ciˆ encias, Universidade do Porto, 4169-007 Porto, Portugal Correspondence should be addressed to Jorge Garrido; jjg@isep.ipp.pt Received 2 December 2013; Revised 17 January 2014; Accepted 22 January 2014; Published 11 March 2014 Academic Editor: Leonardo Palmisano Copyright © 2014 Carlos Fernandes et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Pesticides continue to play an important role in pest management. However, the intensive pesticide application has triggered several environment negative efects that cannot be disregarded. In this study, the inclusion complex of pyrimethanil with HP--CD has been prepared and characterized by proton nuclear magnetic resonance spectroscopy. Te formation of the pyrimethanil/HP--CD inclusion complex increased the aqueous solubility of this fungicide around fve times. To assess the infuence of microencapsulation on the environmental photostability of the fungicide, the photochemical degradation of pyrimethanil and pyrimethanil/HP-- CD inclusion complex has been investigated in diferent aqueous media such as ultrapure and river water under simulated solar irradiation. Te studies allow concluding that pyrimethanil/HP--CD inclusion complex increases signifcantly the photostability of the fungicide in aqueous solutions, especially in natural water. Actually, the half-life of pyrimethanil/HP--CD inclusion complex was increased approximately by a factor of four when compared to the free fungicide. Te overall results point out that pyrimethanil can be successfully encapsulated by HP--CD, a process that can improve its solubility and photostability properties. 1. Introduction Farmers use a wide range of chemical compounds to limit damage losses in agriculture upcoming from pests. In fact, nowadays, a large percentage of crops are destroyed before harvest due to the presence of pests for instance of fungus origin [1]. In order to minimize the damage provoked by pests, chemical compounds, such as pesticides, are widely used in the agricultural production. Tey can prevent or reduce losses and thus increase yield as well as the quality of the product [2]. Scientifc research has been intense in pesticides area either with the goal of increasing the efcacy and reducing the nontarget efects or for reducing their environmental risks [3–6]. Te increase of pesticides consumption does not nec- essarily refect the amount of pesticide that is actually applied to pests, partly because pesticide delivery systems are inefcient [7]. Some estimates concluded that less than 1% of applied pesticides really reach the targets [8]. Sunlight photodegradation is one of the most destructive pathways for pesticides afer their release into the environment. In fact, photochemical reactions are one of the most frequently described transformations of pesticides in the environment. Terefore, studies on the photodegradation processes can provide a better knowledge on the transformations processes of pesticides in the environment and consequently on their oxidation/degradation rate [9, 10]. A class of pesticides which presents risks for environment is the fungicides. Actually, the regular use of this type of compounds can potentially pose a risk to the environment, particularly if their residues persist in the soil or migrate of-site and enter waterways causing adverse impacts on the health of terrestrial and aquatic ecosystems. However, the risk to the environment posed by the use of fungicides in Hindawi Publishing Corporation International Journal of Photoenergy Volume 2014, Article ID 489873, 8 pages http://dx.doi.org/10.1155/2014/489873