Hiroi T, Jin J, Takeuchi T. Photometric detection of cyclodextrins in liquid chromatography by using iodine generated electrochemically in-situ.
Anal Bioanal Chem 2005;
381:1089-94. [PMID:
15688150 DOI:
10.1007/s00216-004-3004-4]
[Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2004] [Revised: 11/29/2004] [Accepted: 12/01/2004] [Indexed: 11/30/2022]
Abstract
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.
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