Abstract: The polarographic method was employed to investigate the supermolecular system of acid cyanine 5R and with cyclodextrins. It was shown that the reducing peak formed by AC 5R in Na_2HPO_4-KH_2PO_4 solution at pH=7.0 was well-defined, stable and sensitive with a peak potential near -0.60 V (vs. SCE). Variations of AC 5R concentrations with the peak currents and the peak height of second derivative polarographs fell in the linear regions of 3×10~(-8)～6×10~(-5) mol/L (r=0.9926～0.9991). The determining limit was 6×10~(-9) mol/L, RSD was 1.16%(n=10) and the standard recovery was 95.9%～103.3%. The polarographic method established is capable of application in the quantitative analyses of AC 5R. In addition, the effects of various cyclodextrins on the electrochemical behavior of AC 5R were also studied. The inclusion constants were calculated by electric current method, and possible factors which influence the inclusion of AC 5R and various of cyclodentrins are discussed.

Key words: Acid cyanine 5R, Polarographic method, Cyclodextrins, Supramolecular system, Electric current method, Inclusion constants, Inclusion rate