Preconcentration and speciation of arsenic by using a graphene oxide nanoconstruct functionalized with a hyperbranched polyethyleneimine.

A column sorbent for arsenic was obtained through immobilization of highly branched polyethylenimine (PEI) on graphene oxide (GO). The composite material enables speciation of arsenic by tuning the pH of the sample solution which governs the surface charge of the sorbent, depending on whether amino groups (-NH) are present (at high pH) or ammonium groups (-NH; at low pH). The composite can be applied to improved speciation of arsenic (compared to unmodified GO).