Analytical Sciences

Determination of Acetaldehyde in Fuel Ethanol by High-Performance Liquid Chromatography with Electrochemical Detection

Adelir A. SACZK, Leonardo L. OKUMURA, Marcelo F. DE OLIVEIRA, Maria Valnice B. ZANONI, and Nelson R. STRADIOTTO

UNESP, Department of Analytical Chemistry, Rua Prof. Francisco Degni s/n, Quitandinha, 14800-900, Araraquara-SP, Brazil

The cyclic voltammetric behavior of acetaldehyde and the derivatized product with 2,4-dinitrophenylhydrazine (DNPHi) has been studied at a glassy carbon electrode. This study was used to optimize the best experimental conditions for its determination by high-performance liquid chromatographic (HPLC) separation coupled with electrochemical detection. The acetaldehyde-2,4-dinitrophenylhydrazone (ADNPH) was eluted and separated by a reversed-phase column, C₁₈, under isocratic conditions with the mobile phase containing a binary mixture of methanol/LiCl_(aq) at a concentration of 1.0 × 10^-3 M (80:20 v/v) and a flow rate of 1.0 mL min^-1. The optimum condition for the electrochemical detection of ADNPH was +1.0 V vs. Ag/AgCl as a reference electrode. The proposed method was simple, rapid (analysis time 7 min) and sensitive (detection limit 3.80 µg L^-1) at a signal-to-noise ratio of 3:1. It was also highly selective and reproducible [standard deviation 8.2% ± 0.36 (n = 5)]. The analytical curve of ADNPH was linear over the range of 3 - 300 mg L^-1 per injection (20 µL), and the analytical recovery was > 99%.

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