Reversed-phase high-performance liquid chromatography and amperometric detection of 3-O-methyl isoprenaline sulphate: application to studies on the presystemic metabolism of d-isoprenaline in man.

A selective method for the determination of 3-O-methyl isoprenaline sulphate in human urine and blood plasma has been developed using reversed-phase high-performance liquid chromatography with amperometric detection. The sulphoconjugate was subjected to acidic hydrolysis and the liberated 3-O-methyl isoprenaline was isolated by organic extraction and conventional cation exchange. An internal standard of 3-O-methyl isoetharine was synthesized from commercially available isoetharine and used to correct for recovery losses. The assay was shown to be linear over the range 5 ng/ml to 20 micrograms/ml with a limit of detection of 2 ng/ml. The reliability of the analytical method was examined together with its applicability to in-vivo studies in man.