Assay procedures for the determination of biogenic amines and their metabolites in rat hypothalamus using ion-pairing reversed-phase high-performance liquid chromatography.

Procedures are described for the simultaneous determination, by high-performance liquid chromatography of adrenaline, noradrenaline, dopamine and 5-hydroxytryptamine using laurylsulphate as pairing ion and for the separate simultaneous determination of vanillylmandelic acid, dihydroxyphenylacetic acid, 3-methoxy-4-hydroxyphenylethylene glycol, 5-hydroxyindoleacetic acid and homovanillic acid using tetraethylammonium as pairing ion. Sample preparation consists of protein precipitation only and octadecylsilane coated silica is used for both sets of determinations as is electrochemical detection. The chromatographic basis of each separation is discussed in the light of modern ideas of ion exchange and desolvation to enable the method to be modified chromatographically if other compounds are to be resolved or the assay method modified. The quantitative aspects of the methods are detailed and applied to amine and metabolite levels in rat hypothalamus. The values determined together with their sample variation and estimated limits of detection are quoted.