Norepinephrine and dopamine: assay by mass fragmentography in the picomole range

Gas chromatography-mass spectrometry makes possible the simultaneous measurement of norepinephrine and dopamine in concentrations of 0.1-milligram tissue samples. Specificity of the assay is confirmed both by the retention time of the compound and by the mass to charge ratio of the fragments recorded. The sensitivity is of the order of 0.5 picomole, and linearity of the response is maintained up to at least 200 picomoles.