High-sensitive determination of coenzyme Q10 in iodinate-β-cyclodextrin medium by inclusion reaction and catalytic polarography

A novel polarographic method for the determination of coenzyme Q10 in β-cyclodextrin (β-CD) and iodinate system is proposed. The stability of coenzyme Q10 to light was improved by the formation of coenzyme Q10-β-CD inclusion complex. In addition, the sensitivity for the determination of coenzyme Q10 was enhanced by both the formation and the polarographic catalytic wave of the inclusion complex in the presence of iodinate. In 0.1 mol/L HAc-NaAc (pH 4.7)-5.0 × 10−5 mol/L β-CD-1.2 × 10−3 mol/L potassium iodinate-ethanol/water (60:40, v/v) medium, coenzyme Q10-β-CD inclusion complex yielded a sensitive association/parallel catalytic wave. The second-order derivative peak current of the catalytic wave was proportional to coenzyme Q10 concentration in the range of 6.0 × 10−8-2.5 × 10−7 mol/L, and the detection limit was 1.0 × 10−8 mol/L. The proposed method has high analytical sensitivity and is allowed to determine coenzyme Q10 under light.