Electrochemical method for quantitative determination of trace amounts of disperse dye in wastewater

The electrochemical behaviour of Disperse Red 13 dye at a glassy carbon electrode was investigated in both organic and aqueous organic mixtures. Best results were obtained in N,N-dimethylformamide/Britton-Robinson buffer (1:1, v/v), which displays a well-defined peak at -0.40V (vs Ag/AgCl) owing to reduction of the protonated nitro group. This method can be successfully applied to the electroanalytical determination of Disperse Red 13 in a very simple and inexpensive way. All the differential pulse voltammetry parameters were optimised by using a glassy carbon electrode modified with poly(glutamic acid) films. The targeted analytical method presented a linear response from Disperse Red 13 concentrations between 2.5x10(-7) and 3x10(-6)moll(-1) (r=0.997), with a detection limit of 1.5x10(-8)moll(-1) and recoveries of 89.7-95.10% in water samples. Disperse Red 13 was successfully determined in textile industry wastewater by means of the proposed method after pre-extraction in a solid-phase extraction cartridge.