Resolution by polarographic techniques of the ternary mixture of captan, captafol and folpet by using PLS calibration and artificial neuronal networks.

The simultaneous polarographic determination of the ternary mixture of captan-captafol and folpet is studied. The polarographic signals of these compounds in their mixture show a high overlapping. For this reason different chemometric methods such as PLS, PCR and artificial neuronal network (ANN) have been utilized for the simultaneous determination of these compounds in mixtures. The calibration model is built from solutions containing river water of known pesticide concentrations and the signals obtained by Sampled DC and DPP (differential pulse polarography) have been used. The analysis of both synthetic and real samples (river water) has been carried out by PLS with satisfactory results in most cases. It is possible to determine 0.25 ppm of each pesticide in river water samples after a preconcentration step by extraction into diethyl ether. ANN has also been applied to improve the results obtained by the PLS tool when the sampled DC current is recorded or when liquid-solid extraction with C18 cartridges is performed.

Study and determination of the pesticide Imidacloprid by square wave adsorptive stripping voltammetry.

An electroanalytical method has been developed for the detection and determination of the pesticide 1-(6-chloro-3-pyridylmethyl)-N-nitroimidazolidin-2ylidineamine (Imidacloprid) by square wave adsorptive stripping voltammetry on a hanging mercury drop electrode (HMDE) in aqueous solution with Britton-Robinson buffer as supporting electrolyte. The best adsorption conditions were found to be pH 7.2, an accumulation potential of -1050 mV (HMDE vs. Ag/AgCl-KCl 3M) and an accumulation time of 50 s. Effects of square wave frequency, step potential and pulse amplitude were examined for the optimization of instrumental conditions. Calibration curve is linear in the range 2 x 10(-8)-5 x 10(-7) M with a detection limit of 1.6 x 10(-8) M (Clayton et al. method). The method is applied to the direct determination of the pesticide in river water samples. For a concentration of 4.1 x 10(-8) M a recovery value of 104+/-3% is obtained. In order to determine lower concentrations, previous preconcentration and cleaning steps (liquid-liquid extraction into CH(2)Cl(2) and solid-phase extraction with Sep-Pak C(18) cartridges) are carried out. The recovery values obtained in spiked river water are 89+/-4% for 2 x 10(-8) M and 90+/-6% for 8 x 10(-9) M.

Trastornos neuropsicologicos en las primeras etapas de la enfermedad de Parkinson / Neuropsychological disorders during the first stages of Parkinson's disease

Presentamos 19 pacientes con enfermedad de Parkinson en estados I a III. Los pacientes fueron sometidos a una evaluacion neuropsicologica en cinco funciones. Los resultados se analizaron segun la frecuencia de aparicion y un indice de severidad de los trastornos (It) en el grupo total de 19 pacientes y en un subgrupo de casos menores de 65 anos (12 pacientes). Nuestra investigacion tiende a corroborar la presencia de trastornos neuropsicologicos en la mayoria de los pacientes. La alteracion de la memoria fue el trastorno mas frecuente en ambos grupos (89 vs 83%) seguido de dificultades construccionales (78 vs 75%). El It: (0: ausente a 1: severo) mostro compromiso moderado en el grupo total (menor de 0,55) y leve en el subgrupo menor de 65 anos (menor de 0.4). Solo un paciente del grupo total presento compromiso del lenguaje (afasia anomica) y reunio los criterios del DSM III para el diagnostico de demencia, los demas pacientes presentan alteraciones cognitivas especificas que ameritan futuras evaluaciones para definir su naturaleza, evolucion y pronostico.