This study was concerned with the development and improvement of analytical procedures using liquid chromatography with electrochemical detection for the determination of activity of tyrosine hydroxylase, tryptophan hydroxylase, and certain individual amines.

The developed methods exhibit sensitivity and selectivity comparable or superior to methods presently in use.

A simplified procedure for the determination of 5-hydroxytryptamine, 5-HT, has also been investigated. The analysis time is considerably shortened by eliminating the usual isolation step through the proper choice of homogenization conditions. Sample handling capability is, thus greatly increased.

The neurotransmitters, catecholamines and indoleamines have been investigated extensively during the recent past. A number of assay procedures have been reported for the study of the rate limiting, hydroxylating enzymes as well as the neurotransmitter levels.

The currently reported methods for the determinations of tyrosine hydroxylase and tryptophan hydroxylase focus on the improvement of chromatographic conditions, optimization of reaction parameters and minimization of blank levels.