Thesis & Dissertations

Pesticides are used either to control pests or to reduce pest damage on crops or animals. As a consequence they might be present in fresh or processed cow milk. This may occur if animals have been fed with contaminated feed or water or from practices involving pesticides in places where animals are living (stables, beehives). Organochlorines are one of the most dangerous classes of organic pesticides. This class of pesticides has been extensively used even though banned by several counties because of their high persistence, high toxicity, and the ability to accumulate in fatty tissues of animals. So, their residues in foods of animal origin are of great public and regulatory concern. And this is the cause that stands behind the increased number of publications in the recent decade involving these pollutants. The anarchical use of pesticides in agricultural activities in Lebanon has increased the risk of contamination of the food chain with certain residual levels of these chemicals. This has rendered the analysis of pesticide residues in different matrices of great concern. For this, various analytical surveys have been accomplished and several papers published in the past few years in the country. Contamination of waters and different types of fruits and vegetables with different analytical methodologies has been assessed. Dairy products are essential components in the Lebanese diet. Almost every meal contains milk or milk products. Labneh, yoghurt, and different kinds of unpasteurized cheese are not the only ones. Because of this, we decided to analyze fresh and canned bovine milk samples taken from the country covering almost its entire map. The low levels at which organochlorines may be present in milk and the complexicity of the matrix due to the high levels of proteins and fats present imposed the application of an efficient sample preparation method. Solid phase microextraction of the headspace satisfied the requested demands. Gas chromatography equipped with electron capture detector was ideal for the detection of organochlorines. A total of eighteen samples were analyzed but none of the samples showed detectable amounts of the six insecticides of interest.