Study on the polarographic catalytic wave of vitamin P in the presence of persulfate and its application.
The polarographic catalytic wave of vitamin P in the presence of persulfate was studied by linear potential scan polarography and cyclic voltammetry. Vitamin P yielded a single reduction wave in acidic aqueous solution, which was ascribed to a 2e(-), 2H(+) reduction of the carbonyl group in the C-4 position. Actually, the carbonyl group C=O first underwent a 1e(-), 1H(+) reduction to form a neutral free radical, and the further 1e(-), 1H(+) reduction of the free radical was simultaneous with its following chemical reactions. When S(2)O(2-)(8) was present, the free radical of vitamin P was oxidized by both S(2)O(2-)(8) and its reduction intermediate, the sulfate radical anion SO(*-)(4), to regenerate the original, which resulted in the production of a polarographic catalytic wave of vitamin P. Based on this catalytic wave, a novel method for the determination of vitamin P was proposed. In 0.02 M tartaric acid-sodium tartrate (pH 3.3) buffer containing 5.0 x 10(-3) M K(2)S(2)O(8), the peak potential of the catalytic wave was -1.42 V (vs SCE) and the peak current was rectilinear to the vitamin P concentration in the range of 8.0 x 10(-9)-1.0 x 10(-6) M (r = 0.9994, n = 13). The catalytic wave of 2.0 x 10(-7) M vitamin P enhanced the polarographic current 70 times compared with the corresponding reduction wave. The detection limit was 2.0 x 10(-9) M, and the relative standard deviation at the 2.0 x 10(-7) M level was 0.7% (n = 15). The proposed method was used for the determination of vitamin P content in the pharmaceutical preparation of tablets and the medicinal plant Sophora japonica L. without previous separation.
Song
Jun Feng
JF
Institute of Analytical Science, Northwest University, Xi'an 710069, People's Republic of China. songjunf@nwu.edu.cn
He
Ping
P
Guo
Wei
W
D002384:Catalysis; D004563:Electrochemistry / Q000379:methods; D004566:Electrodes; D005609:Free Radicals / Q000032:analysis / Q000737:chemistry; D007700:Kinetics; D010084:Oxidation-Reduction; D011048:Polarography / Q000379:methods*; D017680:Potassium Compounds / Q000737:chemistry*; D012431:Rutin / Q000032:analysis / Q000737:chemistry*; D012680:Sensitivity and Specificity; D029909:Sophora / Q000737:chemistry; D013431:Sulfates / Q000737:chemistry*; D013607:Tablets / Q000737:chemistry
D005609:Free Radicals; D017680:Potassium Compounds; D013431:Sulfates; D013607:Tablets; D012431:Rutin; C009007:potassium persulfate