Spectrophotometric determination of pyruvic acid with p-diethylaminocinnamaldehyde

Abstract

The spectrophotometric determination of pyruvic acid with cinnamaldchyde derivatives, such as p-diethylaminocinnamaldehyde (DEAC), p-morpholinocinnamaldehyde (MC), p-nitrocinnamaldehyde, 3, 4-dimethoxycinnamaldehyde, and 2-franacrolein, was studied. Pyruvic acid was found to react with DEAC and MC to give a red color in aqueous ethanol solution in the presence of strong alkali. It was noticed that DEAC gave higher sensitivity and deeper coloration. The colored product with pyruvic acid showed a bathochromic shift with incrcasing sodium hydroxide concentration and reaction time, and a hypsochromic shift with increasing reaction temperature. The calibration curve followed Beer's law in the range of (00.4)mM pyruvic acid. The coefficient of variation is about 2.2% at 0.2 mM pyruvic acid. To 1 ml of sample, 1 ml of 10N sodium hydroxide solution and 3ml of 0.4w/v% DEAC-ethanol solution were added. The mixture was kept for 25 minutes in a water bath at 40°C. After cooling in water, the absorbance was measured at 495 nm against a reagent blank. The effects of α-ketoglutaric acid and dl-alanine on the absorbance were examined. The procedure is useful for the assay of enzymes which are concerned with pyruvic acid. © 1975, The Japan Society for Analytical Chemistry. All rights reserved.