High-throughput determination of lipopolysaccharide by flow injection analysis using dipicolylamine-type fluorescent probe

Abstract

Endotoxin (lipopolysaccharide: LPS), a bacterial toxin, is currently quantified by batch analysis using a reagent made from Limulus amebocyte lysate (LAL). Although the LAL method is sensitive, a long measurement time and gelation have hindered its application to online water quality monitoring. In this paper, we report a novel high-throughput analytical technique that combines flow injection analysis (FIA) and a dipicolylamine-type fluorescent probe, which was previously reported to exhibit strong fluorescence emission in response to LPS. A comparison of normal and reverse FIA systems revealed that the normal FIA offers more rapid detection with throughput of 30 samples per hour, which is the highest among known LAL methods and alternative LPS detection methods that have been recently reported. On the other hand, the reverse FIA requires much less reagent (480 μL per sample). Continuous online monitoring of water quality and analysis of real samples spiked with LPS were realized by this technique.

Keywords

• Lipopolysaccharide
• Flow injection analysis
• Dipicolylamine
• Pyrene
• Online monitoring