Sensitive Chemiluminescence Determination of Three Thiol Compounds Based on Cu(II)-Catalyzing Luminol Reaction in the Absence of an Oxidant

Abstract

A simple and sensitive flow-injection chemiluminescence method was proposed for the determination of three thiol compounds, namely cysteine, acetylcysteine, and glutathione. Weak chemiluminescence was produced directly by the reaction of these mentioned compounds with luminol in an alkaline solution without adding any special oxidants. The chemiluminescence signal could be significantly enhanced by Cu(II). The proposed method allows the determination of 4.0 × 10⁻⁹ to 1.0 × 10⁻⁷ g/mL cysteine, 7.0 × 10⁻¹⁰ to 1.0 × 10⁻⁷ g/mL acetylcysteine, and 4.0 × 10⁻⁹ to 1.0 × 10⁻⁶ g/mL glutathione with the detection limits of 8 × 10⁻¹⁰ g/mL, 2 × 10⁻¹¹ g/mL, and 7 × 10⁻¹⁰ g/mL, respectively. The proposed method was applied to the analysis of some commercial formulations containing acetylcysteine.

Keywords:

• Chemiluminescence
• Cu(II)
• flow injection
• luminol
• thiol compounds