Serum Chloride Optical Sensors Based on Dynamic Quenching of the Fluorescence of Photo-Immobilized Lucigenin

Abstract.

 This article describes the preparation and performance of an optical sensor for continuous measurement of chloride at extracellular (serum) levels (20–200 mM). The sensor is based on dynamic quenching of the fluorescence of lucigenin which was photo-immobilized on a hydrogel. Quenching occurs via a collisional mechanism, and the decrease in fluorescence intensity on exposure to 100 mM chloride typically is −60%. It allows the determination of chloride in the 1 to 200 mM concentration range, with a precision of ±3 mM at 120 mM. Bromide, iodide and salicylate act as interferents, while the effect of pH and oxygen is negligibly small. The sensor displays strong fluorescence intensity, excellent reproducibility, long-term stability, response times in the order of 2–5 min, and is used in a commercial serum and blood chloride analyzer.