Organic solvent-free reversed-phase ion-pairing liquid chromatography coupled to atomic fluorescence spectrometry for organoarsenic species determination in several matrices.

A novel method has been developed to determine As-containing animal feed additives including roxarsone (ROX), p-arsanilic acid (p-ASA) and nitarsone (NIT), as well as other organic As species (dimethylarsonic acid (DMAA) and monomethylarsonic acid (MMAA)) by ion-pairing high-performance liquid chromatography coupled to hydride generation atomic fluorescence spectrometry (IP-HPLC-HG-AFS). A simple isocratic reversed-phase (RP) HPLC method with a mobile phase containing citric acid and sodium hexanesulfonate (pH 2.0) was developed using a C(18) column. The use of an organic solvent free mobile phase turns this methodology into an environmentally friendly alternative. Several ion pair forming agents, such as sodium hexanesulfonate, tetrabutylammonium bisulfate and perfluoroheptanoic acid, were studied. The limits of detection for As species were calculated in standard solution and resulted to be 0.2, 0.5, 0.6, 1.6, and 1.6 µg As L(-1) for MMAA, DMAA, p-ASA, ROX and NIT, respectively. This method exhibited convenient operation, high sensitivity and good repeatability. It was applied to As speciation in different samples including arugula, dog food, dog urine and chicken liver.

Determinación de fluoruro en aguas de Rinconadillas (Provincia de Jujuy) / Determination of the presence of fluorides in groundwaters to Rinconadillas (Jujuy)

El objetivo de la investigación fue determinar la presencia de fluoruros de aguas procedentes de vertientes y pozos cavados en la localidad de Rinconadillas de la Puna Jujeña. Dicha región fue seleccionada debido a que se quería corroborar la presencia de fluoruros, encontrados en la década del ‘80 por el organismo Agua Potable de la provincia de Jujuy, como así también ver si existía variación en la concentración de este contaminante natural en el transcurso del tiempo. La evaluación se realizó sobre 11 muestras de agua de vertientes y de pozos, que representan la totalidad de las fuentes en toda la localidad de Rinconadillas y alrededores. Otras 9 muestras fueron tomadas de Purmamarca, Tumbaya, Volcán, San Salvador de Jujuy y Palpalá, localidades que se alejan de Rinconadillas. Estas muestras consideradas testigos fueron seleccionadas sabiendo que, en estudios realizados anteriormente, no contenían fluoruros. De la totalidad de las muestras recolectadas en Rinconadillas, el 82 % superó el límite máximo recomendado por el Código Alimentario Argentino mientras que menos del 10% se encontraron por debajo de lo reglamentado. Las concentraciones de esta zona fueron superiores a las registradas en las muestras tomadas como referencias, determinándose diferencias significativas entre ambos grupos (p = 0,001). De las muestras testigos sólo una superó el límite superior recomendado por el Código Alimentario Argentino. Algunas de las concentraciones determinadas en el presente estudio fueron mayores a los registros de 15 años atrás y podrían indicar una variación creciente en el tiempo. Se ha observado que la población se ha dispersado en las cercanías a Rinconadillas con nuevas fuentes de aguas de bebida, que sólo reciben una eventual cloración. Se ha observado también en la población del lugar una marcada fluorosis dentalque debería ser evaluada clínica y epidemiológicamente.

The aim of this study was to determine the presence of fluorides in groundwaters from springs and wells belonging to Rinconadillas, a small town located in “La Puna” in the Province of Jujuy. This region was selected because fluoride has been detected during the '80 by Jujuy Water Agency and a comparative study of fluoride levels would provide information about the variation of concentrations of this “natural” contaminant along the time. In “La Puna” the study was conducted on eleven samples of groundwaters from springs and wells from Rinconadilllas and its surroundings. Nine further samples were obtained in Purmamarca, Tumbaya, Volcán, San Salvador de Jujuy and Palpalá, all ofthem far from Rinconadillas. Those samples were selected as prior studies determined that water from such towns does not contain fluoride. Eighty two percent of all the samples collected in Rinconadillas exceeded fluoride limits stated by Argentine Legislation (AL), while less than ten percent of the samples are below the stated values. Fluoride levels from this area were higher than the levels for the reference samples. For the blank samples, only one exceeds the maximum allowed level. Fluoride levels found in this study were higher than those coming from samples that have been analyzed 15 years ago indicating that fluoride levels in waters are increasing. It has also been observed that the population has moved to Rinconadillas surroundings having a drinking water form newsource that is only eventually chlorinated. A remarkable dental fluorosis is observed in the population, which should be clinically and epidemiologically assessed.

Natural contamination with arsenic and other trace elements in ground waters of Argentine Pampean Plain.

Natural contamination with arsenic and other toxic trace elements was studied on a 50,000 km(2) area of the Pampean Plain in Argentina. The locations where natural sources of arsenic are considered to be of concern continue to grow, and include those associated with soils developed on loess or loessic sediments zones and transported volcanic materials sites. Contents of total arsenic, vanadium, chromium, iron and barium higher than those recommended as maximum allowable levels in drinking waters have been measured. In the case of arsenic, analyses of raw groundwaters yielded levels as high as 600 microg As/l. Reported data are discussed in connection with geological and environmental processes involved in ground water contamination.