A novel method of chemiluminescence detection coupled with high-performance liquid chromatography and its application in direct determination of tartaric, malic and citric acids in fruit juice

Abstract

In the present work, a new method of chemiluminescence detection coupled with high performance liquid chromatography for three organic acids—tartaric, malic and citric acids is described. The detection is based on the enhancement of the organic acids for the chemiluminescence reaction between cerous sulfate (Ce(SO₄)₂) and tris (2,2′-bipyridyl)ruthenium(II) (Ru(bipy)₃²⁺). The latter was immobilized on the cationic ion-exchange resin for obtaining high sensitivity and reducing consumption of expensive reagent. Under the optimal conditions, the linear ranges were 7.5 × 10⁻⁷ g mL⁻¹ to 7 × 10⁻⁶ g mL⁻¹ for tartaric acid, 4.0 × 10⁻⁷ g mL⁻¹ to 1.0 × 10⁻⁵ g mL⁻¹ for malic acid and 1 × 10⁻⁷ g mL⁻¹ to 1.5 × 10⁻⁶ g mL⁻¹ for citric acid, and the detection limits were 1.5 × 10⁻⁷ g mL⁻¹, 2.0 × 10⁻⁷ g mL⁻¹, 4.0 × 10⁻⁸ g mL⁻¹ for tartaric, malic and citric acid, respectively. The proposed method had been successfully applied to the determination of three organic acids in fruit juice – with only filtration and dilution steps.