Determination of autoinducer-2 in biological samples by high-performance liquid chromatography with fluorescence detection using pre-column derivatization

• HPLC–FLD method was established for the quantitative detection of autoinducer-2 (AI-2).
• 2,3-Diaminonaphthalene was used as a derivatization reagent to react with AI-2.
• This method was successfully applied to determine the AI-2 in biological samples.
• Our method is simple, sensitive, cost-effective and interference-free.

Autoinducer-2 (AI-2), as a small-molecular-weight organic molecule secreted and perceived by various bacteria, enables intra- and inter-species communications. Quantitative determination of AI-2 is essential for exploring the bacterial AI-2-related physiological and biochemical processes. However, current strategies for sensitive detection of AI-2 require sophisticated instruments and complicated procedures. In this work, on the basis of the derivatization of AI-2 with 2,3-diaminonaphthalene, a simple, sensitive and cost-effective high-performance liquid chromatography with fluorescence detector (HPLC–FLD) method is developed for the quantitative detection of AI-2. Under the optimized conditions, this method had a broad linear range of 10–14,000 ng/ml (R2 = 0.9999), and a low detection limit of 1.0 ng/ml. Furthermore, the effectiveness of this approach was further validated through measuring the AI-2 concentrations in the cell-free culture supernatants of both Escherichia coli and Vibrio harveyi.