Screening of Toxic Inorganic Arsenic Species in Garlic ( Allium sativum L.)
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Screening of Toxic Inorganic Arsenic Species in Garlic (Allium sativum L.) Hadla Sousa-Ferreira & Mariela N. Matos-Reyes & M. Luisa Cervera & Sergio L. Costa-Ferreira & Miguel de la Guardia
Received: 29 July 2010 / Accepted: 30 November 2010 / Published online: 18 December 2010 # Springer Science+Business Media, LLC 2010
Abstract It has been evidenced that arsenic in garlic is present in the most toxic inorganic species As(III) and As (V). A non-chromatographic speciation method has been developed for the screening of inorganic toxic species of As in garlic samples by hydride generation atomic fluorescence spectrometry. The determination of As(III) and As(V) was based on the different efficiencies of hydride generation with NaBH4 with and without a previous reduction with ascorbic acid and KI using a system of two proportional equations corresponding to these two different measurement conditions. The extraction efficiency of total arsenic and the stability of As(III) and As(V) in different extraction media (sulphuric acid, perchloric acid, and methanol/water) were evaluated. Based on the extraction yield and the stability of extracted species, 1.0 mol L−1 H2SO4 was selected as the best extracting solution for speciation analysis. The methodology developed allows us a limit of detection of 0.8 and 0.6 ng g−1 for As(III) and As(V), respectively. The relative standard deviation values were 4% for As(III) and 7% for As(V). This method was applied to determine As(III), As(V), and total As in different
H. Sousa-Ferreira : S. L. Costa-Ferreira Universidade Federal da Bahia, Instituto de Química, Campus Universitário de Ondina, Salvador, Bahia 40170-290, Brazil M. N. Matos-Reyes : M. L. Cervera (*) : M. de la Guardia Department of Analytical Chemistry, University of Valencia, 50 Dr. Moliner Street, 46100 Burjassot, Valencia, Spain e-mail: [email protected]
Spanish garlic samples. The arsenic (III) content varied from 17.1 to 22.1 ng g−1 and As(V) from 54.7 to 67.6 ng g−1. The accuracy of the method was confirmed by the analysis of a certified reference material of tomato leaves treated in the same way as the garlic samples. Keywords Arsenic . Atomic fluorescence spectrometry . Risk assessment . Speciation . Extraction . Garlic
Introduction Arsenic has been classified by the International Agency for Research on Cancer as carcinogenic to humans. However, the bioavailability and toxicity of arsenic present in food depend largely on its chemical form, being As(III) and As (V) as the most toxic species. The toxicity of the organic arsenical species is lower than that of inorganic ones, and arsenobetaine (AB), a trimethylated specie, is recognized as non-toxic. The LD50 (expressed in grams per kilogram) are 0.0345, 1.1, 1.8, >10.0, and >6.5 for As(III), monomethylarsonic acid, dimethylarsinic acid, AB, and arsenocholine, respectively (Shiomi 1994). So, in order to assess the risk of As for human health, the determination of the inorganic arsenic present in foods is of great importance. It is well-known that fish is the ki
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