Arsenic Extraction and Speciation in Plants Grown on Arsenic Contaminated Soils
Quantitation of arsenic species in plants is important because of the toxicity of the element. Since this toxicity is dependent on both form and concentration of the various arsenic species present, the determination of total arsenic alone is not sufficient for risk assessment purposes. The current extraction methods to study this subject for plants are diverse and inconsistent. Plant samples were collected from Deloro, Ontario where there was an ore processing facility. The operation of the facility resulted in a large arsenic contaminated site through which the Moira river flows and on which various plants are growing. A sequential extraction method was developed using various solvents such as water, 1:1 water-methanol, methanol, 0.1 M NaOH and HCl of varying strengths (0.01 M to1.0 M) in order to extract the various arsenic species without altering their form. Total arsenic in plants was determined by acid digestion and ICP-AES or hydride generation (HG)-AAS while various arsenic compounds were determined in the extracts by HPLC with HG-AAS and ICP-MS detection. The results of development of the sequential arsenic extraction method were published (Talanta 72 (2007) 1507-1518). Further investigations on arsenic in plants were conducted using the developed sequential extraction method and many plant samples collected from abandoned goldmine sites at Deloro.