Determination of total As in onion plants growing in contaminated substrates by total reflection X-ray fluorescence Lue ´-Meru ´ Marco ´ Parra Received: 13 July 2010 / Published online: 23 September 2010 Ó Akade ´miai Kiado ´, Budapest, Hungary 2010 Abstract The onion (Allium cepa L.) is one of the most important cultivars in the world and its production level occupies the second place in Venezuela. It becomes important to develop analytical procedures for arsenic determination and to study the effect of this element on the cultures, as well the absorption, transport and translo- cation processes. A TXRF method for As determination in onions was developed. Two treatments were applied to the onion plants, As contaminated and control. The contami- nant was added to the plants to an amount of 100 lg, in a single time 3 weeks after the transplant of plantlets. The green leaves bulbs, and roots together with the stems were separated 45 days after transplant and analyzed by TXRF and HG-AAS for total Arsenic determination. A good agreement was found between these two techniques, demonstrating the accuracy of the TXRF procedure. It was found that the highest concentration corresponded to the root and stems (37 ± 31 lgg -1 ), followed by the bulbs (11 ± 7 lgg -1 ), being the smallest level found in the green leaves (4 ± 3 lgg -1 ). At low As contamination levels of 0.25 lgg -1 , a risk for translocation of the toxic element to the edible parts of the onion plants exists. At this level the normal development of the plant is not affected, being the only exception the root length, which is significantly higher in the contaminated treatment. Keywords Onion arsenic Á TXRF Á HGAAS Introduction The toxicity of some As species is widely known. This element causes an important concern in the field of envi- ronmental monitoring due to its widespread use in the industry and agriculture, and consequent distribution in the geosphere [1–5]. The arsenic is found in a large variety of samples (fresh and sea waters, sediments, soils, marine organism, body fluids, and in a great variety of species in variable amounts) [1, 2, 6–8]. The mobilization of arsenic as consequence of the anthropogenic factors exceeds the natural rate (from marine sedimentary rocks, volcanic rocks or fossil fuels) by three folds compared to the dis- tribution in aquatic ecosystems [3, 5]. In ground waters the As levels could exceed 20 mg L -1 ,while in drinking water may vary from 0.05 to 60 mg L -1 , 2 or 3 orders of mag- nitude higher than those of most natural waters consumed by humans [9, 10]. The contamination of water and air is reported in Argentina, Chile, USA and Sweden, as a result of copper smelters. In Taiwan and India numerous papers reported the contamination of drinking water with consequences in public health [11, 12]. Certain plants growing in enriched soils can accumulate extremely higher amounts of this element specially in places where arsenical compounds are used for insect control or undesired plagues [13–15]. Some organic As compounds are used as herbicides, and are present together with the inorganic species in soil samples [5, 16]. The total amount of the ingested As daily could be influenced then by the type of food in the diet [6, 16, 17]. The income of the element in the food chain could be a consequence of the use as insecticide and pesticide for animal growth, veterinary medicine, etc. The most toxic arsenic species are the inorganic As (III) and As (V). In waters and soils the As is mainly present as As(III) and As(V), but the L.-M. Marco ´ Parra (&) Dpto. Quı ´mica y Suelos, Decanato de Agronomı ´a, Universidad Centroccidental Lisandro Alvarado, Tarabana, Cabudare, Edo. Lara, Venezuela e-mail: luemerumarco@yahoo.es 123 J Radioanal Nucl Chem (2011) 287:479–484 DOI 10.1007/s10967-010-0834-8