A convenient colorimetric assay for Cr(VI) detection based on homogeneous Cu(II)-GMP system with oxidoreductase-like activity

Hexavalent chromium (Cr(VI)) is an environmental pollutant and recognized as a human carcinogen. Therefore, it is necessary to develop a simple and sensitive detection technique for Cr(VI). Herein, it is found that Cu2+ interacts with guanosine 5 '-monophosphate (GMP) to form a homogeneous Cu(II)-GMP complex (Cu2+center dot GMP) that efficiently displays the oxidoreductase-like catalytic activity. Cu2+center dot GMP can catalyze the oxidation between Cr(VI) and substrate 3,3 ',5,5 '- tetramethylbenzidine (TMB), resulting in color change recognized by the naked eyes. Base on this, a convenient colorimetric assay for Cr(VI) detection was developed. The detection limit (3 sigma/s) of this sensor for Cr(VI) was 23 nM with a linear range of 0.1-25 mu M. Moreover, the proposed assay was successfully applied to detect Cr(VI) in different environmental water samples with satisfactory recoveries. Our method is simple, efficient, rapid and cost-effective for Cr(VI) detection without the need for complicated material preparation or special separation, which shows great potential in environmental monitoring.