A nanoparticulate liquid binding phase based DGT device for aquatic arsenic measurement

A nanomaterials-based DGT device constructed with commercial dialysis membrane as diffusive layer and nanoparticulate Fe3O4 aqueous suspension as binding phase is developed and validated for in situ aquatic arsenic measurement. The Fe3O4NPs binding phase is capable of quantitatively accumulated both As(III) and As(V) species. As(III) and As(V) species coexist in the vast majority of environmental water samples. The large difference in diffusion coefficients of As(III) (DAs(III)=3.05×10(-7)cm(2)s(-1)) and As(V) (DAs(V)=1.63×10(-7)cm(2)s(-1)) makes the accurate DGT determination of total arsenic concentration of samples containing both species difficult. An effective diffusion coefficient (DAs¯=DAs(III)[1/(1+x)]+DAs(V)[x/(1+x)],where,x=As(V)/As(III)) approach is therefore proposed and validated for accurate DGT determination of total arsenic when As(III) and As(V) coexist. The experimental results demonstrate that for samples having As(V)/As(III) ratios between 0.1 and 0.9, the DGT determined total arsenic concentrations using DAs¯are within ±93-99% of that determined by ICP-MS. The general principle demonstrated in this work opens up a new avenue of utilizing functional nanomaterials as DGT binding phase, paving a way for developing new generation nanomaterials-based DGT devices that can be readily produced in massive numbers at low costs, facilitating the widespread use of DGT for large-scale environmental assessment and other applications.