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An HPLC-UVDAD method for determination of dimethoate, 2,4-dichlorophenoxy acetic acid (2,4-D), mecoprop (MCPP) and linuron in environmental waters was developed. The water samples were concentrated and extracted by a solid phase extraction (SPE) method on Bond Elut PPL cartridges. After extraction the investigated compounds were separated on Stability RP Pesticides chromatographic column using mobile phase composed of acetonitrile- water-acetic acid in volume fractions of 39:59:2 and flow rate of 0.7 mL/min. Ultraviolet absorption detection was carried out for dimethoate, 2,4-D and MCPP at 229 nm, and for linuron at 249 nm. Recoveries made from 500 mL of drinking waters using solid phase extraction ranged between 64.3–92.1 %. The method was applied to environmental waters in Macedonia that receive runoffs from agriculture lands. The levels of pesticides under study ranged between 0.31 μg/L and 7.05 μg/L, depending on the compound and sampling period.

Abstract:The Diels-Alder reaction of hexachlorocyclopentadiene with norbornadiene gives aldrin but theoretically three other diastereofacial isomers are possible. On oxidation these isomers can generate eight adducts one of which is known as dieldrin. All these, as well as the corresponding reactions with hexafluorocyclopenadiene were studied by semiempirical (AM1 and PM3) and hybrid density functional (B3LYP) methods. Besides the energy levels, the transition states were calculated for the reactions leading to the diastereofacial isomers of aldrin, which indicate that aldrin is the favored product of the reaction both from thermodynamic and kinetic point of view.