Characterization of TBP containing polysiloxane membrane/insulator/semiconductor structures for hexavalent chromium detection

A hexavalent chromium-sensitive EMIS sensor (electrolyte membrane insulator semiconductor sensor) is prepared by deposition of a tributylphosphate (TBP) ionophore-containing siloprene membrane on a Si/SiO2/Si3N4 structure. The developed EMIS sensor was studied by means of impedance spectroscopy, capacitance-voltage, X-ray photoelectron spectrometry and FT-IR spectroscopy. From the flat-band shift of the EMIS structure, the nersntian response to the anionic species Cr2O7− was demonstrated. The linear range of detection is 10− 4 M to 10− 1 M and the detection limit is 10− 5 M. Sulfate and chloride anions are shown not to be interfering whereas carbonate ions present a pKpot equal to 0.19.