Microanalyses of β-cyclodextrin in plasma by high-performance liquid chromatography

Abstract

Procedures for the micro-determination of β-cyclodextrin (β-CyD) in plasma were investigated by four methods using high-performance liquid chromatography (HPLC). In methods A and B, underivatized β-CyD was detected with a refractive index detector and determined by the absolute calibration graph method. An NH 2-bonded silica/acetonitrile—water system was used in A and a C 18-bonded silica/methanol—water system in B. In method C, the percarbanilate of β-CyD was separated on a C 8-bonded silica column with acetonitrile—water and determined using γ-CyD as the internal standard with a UV detector at 231 nm. In method D, the per[1- 14C]acetate of β-CyD was fractionated on a silica column with n-hexane—ethanol containing 1% of water and the radioactivity of each fraction was measured with a liquid scintillation counter. γ-CyD was used as the internal standard. Interfering plasma proteins were removed by centrifugal ultrafiltration with an MPS-1 micropartition system. Method B was superior to the other methods with respect to ease of sample preparation, sensitivity and time required for analysis. The cumulative amount of β-CyD in the mesenteric vein absorbed from the rat intestinal lumen after administration of phenobarbital—β-CyD complex in a closed loop method was determined by the use of method B.