title: Study on the polarographic catalytic wave of vitamin P in the presence of persulfate and its application.
abstract: 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.
authors: Institute of Analytical Science, Northwest University, Xi'an 710069, People's Republic of China. songjunf@nwu.edu.cn
authors: Jun Feng
authors: JF
authors: Song
authors: Ping
authors: P
authors: He
authors: Wei
authors: W
authors: Guo
mesh_terms: 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
chemical_list: D005609:Free Radicals; D017680:Potassium Compounds; D013431:Sulfates; D013607:Tablets; D012431:Rutin; C009007:potassium persulfate