LINEAR SWEEPING POLAROGRAPHIC DETERMINATION OF ISATIN IN NATURAL INDIGO COMPOUND TABLETS

In an ammoniacal buffer medium of pH 9.8,the electro-chemical behavior of 2,3-isatin (ISA) was studied by linear sweeping voltammetry and cyclic voltammetry.Two reductive waves of ISA were observed with peak potentials,at -0.51 V and -0.59 V (vs.SCE).Linear relationship between the values of 2nd derivative of peak current (i″p) at Ep of -0.51 V and of concentration of ISA was obtained in the range of 2×10-6-2×10-4mol·L-1 (r=0.999 5).The detection limit was found to be 7×10-7mol·L-1 of ISA.Precision tested at the concentration level of 4×10-5mol·L-1 of ISA gave a value of RSD (n=11) of 1.29%.The proposed method has been used in the determination of ISA in natural Indigo compound tablets.