Potentiometric Screen-Printed Bisensor for Simultaneous Determination of Chromium(III) and Chromium(VI)

A disposable dual screen-printed electrode was designed and evaluated for the direct and simultaneous determination of chromium(VI) and chromium(III) in batch and flow analysis. For this purpose a carbon screen-printed bielectrode was modified with a graphite-epoxy composite which contains diphenylcarbazide and another graphiteepoxy composite prepared with di(2-hydroxyphenylimino) ethane. The principal analytical parameters of the potentiometric responses in batch and flow analysis were optimized and calculated. The bisensor shows optimal detection limits of 7.7 x 10(-7) M and 7.9 x 10(-6) M in static mode, and 9.0 x 10(-7) M and 1.2 x 10(-5) M in flow analysis for hexavalent and trivalent chromium, respectively. This potentiometric device was employed with successful results to determine both chromium species in leachates from municipal solid waste landfills.