1. Introduction
Exposure to toxic inorganic arsenic (As) is linked to an increased
risk of cancer [1,2]. Thus, methods capable of separating and
measuring specific chemical forms of As in dietary components
are necessary for accurate risk assessment. Food is the most
obvious vehicle for toxic chemicals to enter the human body
and therefore methods to evaluate the safety of foods from the
aspect of contaminants are of great importance. In addition, food
analysis can provide a measure of the degree to which the agricultural
production system might be polluted. As the toxicity
of elements such as As depend upon their molecular environment,
it is important to determine which chemical species are
present in a foodstuff as well as the total concentration of the
element.
High concentrations of As are sometimes found in environmental
waters. Severe health problems in some areas of south Asia are
caused by high concentrations of inorganic As in ground water used
as drinking water. In Japan, 80% of dietary As comes from seafood.
It is well known that the As concentrations in seafoods such as fish,
shellfish and seaweeds are much higher (generally g g−1 level)
than those of other foods such as grains, vegetables and meat (generally
ng g−1 level) [3–18], and that most As in seafood is in the
form of non-toxic arsenobetaine. Of agricultural products, rice is