Flow-injection fluorometric quantification of succinate in foodstuffs based on the use of an immobilized enzyme reactor Original Research Article

A method for the quantification of succinate by flow injection analysis was developed using an immobilized-enzyme reactor and a fluorescence detection. Succinate was quantified using a co-immobilized isocitrate lyase (ICL) and isocitrate dehydrogenase (ICDH) reactor. Succinate was converted to isocitrate by ICL in the presence of glyoxylate, and then the produced isocitrate was oxidized with NADP+ by ICDH. The NADPH produced by the ICL–ICDH reactor was monitored fluorometrically at 455 nm (excitation at 340 nm). A linear relationship between sensor responses and concentration of succinate was obtained in the range of 5–200 μM. The relative standard deviation for 10 successive injections was 1.01% at the 200 μM level. This analytical method was applied to the quantification of succinate in shellfishes and Japanese sakes, and the results showed good agreement with those obtained using conventional method (F-kit method).