A Determination Of Arsenic In Sugar Cane Soils And Foliar Tissue From Municipio, Lara State, Venezuela By Hydride Generation Atomic Absorption Spectroscopy

Author(s): Maria De Los Angeles Yepez, Marcos Reina, Francis Segura, Jorge Amaya, Jesus Arroyo, Beatriz Arrieche, Saida Matute, Lue-Meru Marco P

The total arsenic levels were determined in sugar cane soils and foliar tissue from crops of the Municipio Palavecino, Lara State, Venezuela using the method of hydride generation atomic absorption spectrometry. The samples were taken from six farms of the zone. In the preparation procedure optimized amounts of KI and HCl were added to the soil slurry in order to perform the predigestion and prereduction of the arsenic. Foliar tissue samples were analyzed after a wet digestion procedure following a similar procedure as for the soils for the pre-reduction step. After that sodium borohydride 3% in NaOH 1% was added to produce the arsine. An Argon flow was used to transport the arsine to the quartz cell of the spectrometer. Measurements were carried out in a Perkin Elmer 3110 spectrometer with hydride generation module. The arsenic levels in the soil were in the range of 5.75 to 12.13g/g, the accuracy was verified analyzing the NIST standard reference materials San Joaquin Soil and Buffalo River Sediment. The arsenic levels in the foliar tissue samples were in the range of 0.24 to 0.29g/g . The accuracy was verified with the NIST Standard reference material 1573 Tomato leaves. The proposed soil slurry preparation method avoids the possible losses of the traditional digestion procedures with adequate analytical quality. A good agreement was found between the certified values and those obtained with the proposed procedure. The arsenic levels in the soils are lower than the average toxicity threshold value for crop plants. Eventhough the sampled sites are under risk of contamination due to the intensive use of pesticides containing this toxic element. The Arsenic levels in the foliar tissue indicate absorption and transport of this toxic element and the necessity of further studies for the evaluation of the associated risk. Nevertheless, the arsenic concentration in foliar tissue is significantly lower than those values found in risk zones.

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