Ground water samples obtained from West Bengal, India were analyzed for total arsenic and its inorganic species contents by
instrumental neutron activation analysis (INAA). Two anion exchange separation methods using Dowex 1X8 in chloride and acetate
forms were standardized for the speciation of As(III) and As(V) using radiotracers. The method by Dowex 1X8 in the acetate
form was validated using synthetic mixtures of As(III) and As(V), and applied to water samples; the species concentrations
were determined by INAA. The accuracy of the INAA method was evaluated by analyzing the NRCC CRM DORM-2 for total arsenic.
Dissolved inorganic arsenic species were determined in natural waters and selected marine species. Prior to irradiation by NAA samples were preconcentrated and the As(III) and As(V) species separated by APCDT-chloroform extraction. Marine samples were digested by microwave heating. Interpretation of data was achieved by comparing the ratio of As(III)/As(V) in the samples and correlating it with the prevailing environmental conditions.
For the determination of arsenic compounds in terrestrial plant samples, a crucial step is the efficient extraction of arsenic
from the solid plant matrix. However, the use of methanol-water extraction often resulted in low extraction efficiencies of
less than 50%. In this study, eight solid-liquid extraction procedures (mainly based on mechanical mixing and sonication)
were evaluated for the recovery of arsenic species from a submerged freshwater plant, coontail (Ceratophyllum demersum), collected in Moira River, Ontario, Canada. Speciation of As in the extracts was carried out with both anion-, and cation-exchange
HPLC with sector-field inductively coupled plasma mass spectrometric (SF-ICP-MS) detection. The results obtained depended
critically on the extraction solvents used in different extraction procedures. Extraction with methanol-water led only to
9%–44% recoveries of As. A high extraction yield (approximately 82%) was obtained by water extraction. Alkaline hydrolysis
also resulted in high extraction efficiencies (86%–98%), but severe oxidation of As(III) to As(V) was observed. A protease
enzymatic extraction led to a recovery of 48%. Approximately 0.5% of the total As in the plant sample was lipid-soluble. It
was found that the extraction of inorganic arsenic species was suppressed by the presence of methanol in the extraction solvents,
while high content of methanol in the extraction solvents was effective for the extraction of organic arsenic species. Therefore,
it is recommended to perform the extraction both with water alone and with methanol-water (9+1, v/v), in order to obtain the
complete As species profile in terrestrial plants.