Determination of Acetaldehyde Using Immobilized Aldehyde Dehydrogenase in a Flow System and Application to Analysis of Acetaldehyde Content in Liquors

Abstract

The quantity of acetaldehyde was determined using an apparatus containing a reactor with immobilized aldehyde dehydrogenase in a flow line. NADH formed by an enzymatic reaction was fluorometrically detected. The optimal concentration of NAD⁺ in the carrier was determined. Various buffer types were examined as a carrier medium. When the pH of the carrier was 7.8, great peak areas due to NADH were observed for buffers of phosphate, pyrophosphate, HEPES, PIPES-(piperazine-N, N'-bis(2-ethanesulfonic acid)) and triethanolamine, compared with that for Tris buffer. In the pH range from 7.0 to 8.0, the peak area due to NADH increased with the increase of pH in the case of phosphate buffer, in contrast to the case of Tris buffer in which peak area decreased with the increase of pH. When the carrier composed of phosphate buffer (0.1M, pH7.8) was used, the calibration curve for acetaldehyde was linear in the range of 0.2-10μM (r=0.9994). Detection limit (S/N=3) was 0.1μM.Relative standard deviation of peak area at 2μM was 2.6% (n=7). The sampling rate was 40 samples h^-1. This method was applied to the analysis of aldehyde in several liquors, and aldehyde content determined by the method agreed with that determined by a commercially available test-kit method.