A cubic silsesquioxane modified with purpald (r) : preparation, characterization and a voltammetric application for determination of sulfite

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Processo FAPESP: 12/05438-1

Processo FAPESP: 12/11306-0

A novel composite formed by interaction of a octa(3-chloropropyl)octasilsesquioxane modified with Purpald(R), and its subsequent reaction with silver and hexacyanoferrate (III) (AgHSP), was synthesized and initially characterized by Fourier transform infrared spectra (FTIR) and cyclic voltammetry. The cyclic voltammogram of the modified graphite paste electrode with AgHSP, showed one redox couple with formal potential E-theta'=0.64V (vs Ag/AgCl, KNO3, 1.0 mol L-1; v = 20 mV s(-1)), attributed to the Fe2+(CN)(6)/Fe3+(CN)(6) process. The redox couple presents an electrocatalytic response for determination of sulfite. The modified electrode showed a linear response from 7.0x10(-5) to 1.0x10(-3) mol L-1 with the corresponding equation Y(mu A) = 18.05 + 29.983x10(3) [sulfite], and a correlation coefficient of r=0.999. The method showed a detection limit of 0.115x10(-4) mol L-1 with a relative standard deviation of +/- 4% (n = 3) and amperometric sensitivity of 29.983x10(-3)A mol L-1. The modified electrode showed a excellent stability and good reproducibility during experiments.