Flow injection determination of lactate based on a photochemical reaction using photometric and chemiluminescence detection

Abstract

A photochemical method for the determination of lactate using a flow-injection system is proposed. The method is based on the decomposition of lactate in the presence of UO₂²⁺ and Fe³⁺ upon irradiation with UV or visible light. The Fe²⁺ produced in the photochemical process was monitored by measuring the absorbance after complexation with ferrozine (λ_max= 562 nm) or the chemiluminescence (CL) intensity in a luminol system without added oxidant. The range of measurements depended on the length of the irradiation time and the detection system used. The detection limits using CL and photometric detection were 2 ng ml^–1 and 50 ng ml^–1, respectively. The sample throughput was 45 samples h^–1. The usefulness of the method was demonstrated by determining lactate levels in blood serum, milk, yoghurt, beer and pharmaceutical preparations.