Comparative Investigation of Pulsed Electrochemical and Ultraviolet Detections in the Determination of Flavor-Active Aldehydes Separated by HPLC

Electrochemical detection at gold electrodes of flavor-active aldehydes separated by liquid chromatography demonstrates close limits of detection at the 50 ppb level for the three types of molecules studied: saturated, unsaturated, and conjugated. Conversely, UV detection gives worse limits of detection (100 times higher) for saturated aldehydes and better limits of detection (50 times lower) for conjugated ones. Moreover, because the potential of detection of aldehydes allows the simultaneous analysis of alcohols by HPLC-electrochemical detection, a mixture of aldehydes and alcohols, saturated and unsaturated, can be easily studied, while the HPLC-UV analysis gives poor results in this case. This study shows increasing sensitivities of electrochemical detection for aldehydes in the following order: unsaturated saturated conjugated. It is concluded that aldehydes seem to have the same behavior as alcohols, i.e. that the addition of double bonds to a saturated alcohol increases its detection ability. Conjugated aldehydes are an exception to this rule, and some hypotheses explaining their lower ability of adsorption at the oxidized electrode compared to nonconjugated aldehydes are proposed