Spectrofluorimetric study of the β-cyclodextrin:vitamin K3 complex and determination of vitamin K3

Vitamin K-3 (menadione) is an oil-soluble vitamin and not naturally Fluorescent but yields fluorescence when it is reduced. However, it is possible to yield a fluorescent derivative in the region of 407 nm in aqueous medium when complexed to beta -cyclodextrin (CD). A 1:1 stoichiometric ratio and a formation constant of 373 +/- 34 l mol(-1) were obtained for the binary inclusion complex between menadione and P-CD. The measurements were performed at pH 6.2 adjusted by adding 0.1 mol l(-1) citrate buffer solution and 6.4 x 10(-3) mol l(-1) of beta -CD concentration. The calibration graph was linear over the range 0.1-2.0 mg l(-1) with a repeatability of 2.2%; the detection limit was 0.022 mg l(-1) and the limit of quantification limit was 0.073 mg l(-1). The procedure was applied to pharmaceutical formulations. (C) 2001 Elsevier Science B.V. All rights reserved.