Magnetic Fe₃O₄@poly(methacrylic acid) particles for selective preconcentration of trace arsenic species

The authors describe magnetic nanoparticles consisting of an Fe₃O₄ core and a poly(methacrylic acid) coating for dispersive solid phase extraction (DSPE) of arsenic prior to its determination by hydride-generation microwave plasma AES (HG-MP-AES). The particles have an average size of 25 nm, can be prepared at low costs, and provide improved operational safety in combination with plasma generation. The methods allows arsenic to be determined with detection limits (at 3σ/m) of 3.0 ng⋅L⁻¹ for As(III) and of 10.0 ng⋅L⁻¹ of As(V). Recoveries of (spiked) samples range from 99.0 to 102%. This is the first report on the use of HG-MP-AES for speciation and preconcentration of arsenic using DSPE. The method displays detection limits that come close to those of ICP-OES and ICP-MS.