Square-wave voltammetric determination of paraquat at carbon paste electrode modified with hydroxyapatite

The voltammetric behavior of paraquat was investigated at hydroxyapatite-modified carbon paste electrode HAPCPE in K2SO4. A method was developed for the detection of the trace of this herbicide, based on their redox reaction. The reduction peaks of paraquat were observed around - 0.70 V and - 1.00 V (vs. SCE) in square-wave voltammetry. Experimental conditions were optimized by varying the accumulation time, apatite loading and measuring solution pH. Calibration plots were linear under the optimized parameters over the herbicide's concentration range 8-200 x 10(-7) mol L-1, with a detection and quantification limits about 1.5 x 10(-8) mol L-1 and 6.4 10(-8) mol L-1, respectively.