Abstract: A test strip for the detection of cadmium was developed by immobilizing 1-(4-nitrophenyl)-3-(3- methyl-pyridyl) triazene, a chromogenic agent specific for cadmium, onto a supporting pad. After the test strip was inserted into a self-made photoelectrical sensor, the reflectivity was recorded as the sensor signal. A standard calibration curve was established between reflectivity and cadmium concentration in standard solution. The results showed that this photoelectrical sensor could detect cadmium over the concentration range of 0.0179－0.2857 mmol/L within 2 min and revealed a detect limit of 0.00348 mmol/L. This technique exhibited the advantages of short assay time and convenient operation. Therefore, this photoelectrical sensor has the potential to apply in the on-site detection of cadmium.

Key words: cadmium, photoelectrical biosensor, 1-(4-nitrophenyl)-3-(3-methyl-pyridyl) triazene