A subnanomole level photoelectrochemical sensing platform for hexavalent chromium based on its selective inhibition of quercetin oxidation.

An indirect photoelectrochemical sensing platform for toxic hexavalent chromium was for the first time constructed based on its redox reaction with quercetin as both the electron donor and photosensitizer on a TiO(2) photoanode, and thus inhibiting the photocurrent quantitatively and selectively. The presence of even 500-fold coexisting Cr(III) does not interfere in the detection of Cr(VI). Under the optimum conditions, the electrode displayed a linear decrease response as the Cr(VI) concentration increased from 1 to 10 nmol L(-1) and from 20 to 140 nmol L(-1) with a detection limit of 0.24 nmol L(-1). Many possible ions in drinking water did not interfere with the detection, and the real sample detection results agreed well with those obtained by GFAAS. This work provide a novel methodology for the simple, low-cost photoelectrochemical detection of Cr(VI) in drinking water.