Assay of human blood aldehyde dehydrogenase activity by high-performance liquid chromatography

A simple and sensitive method for routine analysis of aldehyde dehydrogenase (ALDH, EC 1.2.1.3) activity in human blood has been developed. The assays were performed by incubating diluted whole blood samples in sodium pyrophosphate buffer in the presence of NAD. The aldehyde derived from dopamine, or alternatively the aldehyde from serotonin, was used as the substrate and the acid formed was measured using high-performance liquid chromatography with electrochemical detection. The present method can be performed with a small sample (10-25 microliters) of whole blood and no time-consuming pretreatments of the samples are needed. Six to seven samples can be assayed per hour, and the precision of the method was 2%. For comparison, assays were also performed with two fluorimetric methods, one measuring the formation of indole-3-acetic acid from indole-3-acetaldehyde and the other measuring the rate of acetaldehyde disappearance.