Arsenic is known to be one of the most toxic elements and has serious effects on plants, animals and human health [1]. It is very well known that toxicity depends not only on total concentration but also on chemical species in which this analyte is present. Toxicity of arsenic depends on its chemical form; inorganic arsenic species are more toxic than their organic counterparts and inorganic trivalent form [As (III)] is more toxic than the pentavalent one [As(V)][2,3]. In the present study, an efficient solid phase extraction method based on new functionalized aluminum oxide nanoparticles for preconcentration, speciation and determination of trace amounts of arsenic in different type of environmental, food and biological samples was developed. The effective parameters on arsenic species determination were optimized using two optimization methods: fractional factorial design (FFD) and central composite design (CCD). At pH 1.5, As (III) was selectively extracted and As(V) retained in the sample solution, but at pH 4.5 both As(III) and As(V) were extracted from sample solution. Thus, the total As(III, V) was determined without need for oxidation or reduction process. The concentration of As (V) in the sample solution was calculated easily by subtracting As (III) from total arsenic. Based on three SD of the blank, the detection limits were 1.81 ng L-1and 1.97 ng L-1for As (III) and total As respectively
