Determination of inorganic selenium species by miniaturised isotachophoresis on a planar polymer chip

The use of miniaturised isotachophoresis to allow the simultaneous determination of two inorganic selenium species has been investigated using a poly(methyl methacrylate) chip with a 44-mm-long, 200-mum-wide, 300-mum-deep separation channel. The miniaturised device included an integrated on-column, dual-electrode conductivity detector and was used in conjunction with a hydrodynamic fluid transport system. A simple electrolyte system has been developed which allowed the separation of selenium(IV) and selenium(VI) species to be made in under 210 s. The limits of detection were calculated to be 0.52 mg L-1 for selenium(IV) and 0.65 mg L-1 for selenium(VI). The method allowed the separation of the selenium species from a range of common anions including fluoride, nitrate, nitrite, phosphate, sulfate and sulfite.