Photometric detection of cyclodextrins in liquid chromatography by using iodine generated electrochemically in-situ.
A method has been developed for photometric detection of cyclodextrins (CD) in liquid chromatography using iodine (I2) generated electrochemically in-situ. Iodide ion in the mobile phase was electrochemically oxidized to I2 which was subsequently reacted with I-, in an electrochemical flow cell, forming I3-. The absorbance of I3- was found to be greatly enhanced when CD were present in the mobile phase. The absorbance enhancement was caused by the change in the mole fraction of I3-, because of the inclusion reaction of I3- with CD. On the basis of this phenomenon, CD were detected by means of a photodiode-array UV-visible detector positioned downstream of the electrochemical flow cell. The signals were found to be linearly dependent on CD concentration. Because the formation constants of I3- with CD decrease in the order alpha-CD>beta-CD>gamma-CD, alpha-CD was most detectable by the method. Detection limits were 1.0 micromol L(-1) for alpha-CD, 65 micromol L(-1) for monoG1-beta-CD, 100 micromol L(-1) for beta-CD, and 200 micromol L(-1) for gamma-CD.
Hiroi
Toshiya
T
Department of Chemistry, Faculty of Engineering, Gifu University, 1-1 Yanagido, Gifu, 501-1193, Japan.
Jin
Jiye
J
Takeuchi
Toyohide
T
D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D003505:Cyclodextrins / Q000032:analysis*; D004563:Electrochemistry; D007454:Iodides / Q000737:chemistry; D007455:Iodine / Q000032:analysis / Q000737:chemistry*; D010084:Oxidation-Reduction; D010783:Photometry / Q000379:methods*
D003505:Cyclodextrins; D007454:Iodides; D007455:Iodine