Determination of Sudan IV in chili products by linear sweep polarography

The electrochemical behavior of Sudan Ⅳ was studied by linear sweep polarography.It was found that in a BR buffer medium of pH 7.50,a sensitive reduction wave was given by sudan Ⅳ with its peak potential at -0.935 V(vs.SCE).Linear relationship between the 2nd derivative of peak current of the reduction wave and the concentration of sudan Ⅳ was obtained in the range of 4.00×10-7～8.50×10-6mol/L(r=0.9984),with a detection limit of 2.44×10-7mol/L.The method has been applied to the determination of microamounts of sudan Ⅳ in Chili powder with the recovery in the range of 93.26%～104.53%.