LC-MS/MS method for quantification of 3,4-dihydroxyphenylglycol, a norepinephrine metabolite in plasma and brain regions.

Aim: To evaluate suitability of the LC-MS/MS method to quantify 3,4-dihydroxyphenylglycol (DHPG) that is used as a biomarker for monoamine oxidase (MAO) inhibition. Methods: DHPG was extracted using alumina basic cartridges and quantified on a triple quadrupole mass spectrometer using negative electrospray ionization, without the use of derivatization reagents. Results: Modulation of DHPG levels was observed following administration of selective and nonselective MAO inhibitors and results were in correlation with historical MAO inhibition potential of compounds. Conclusion: The proposed method is sensitive enough to measure plasma DHPG levels and DHPG can be used as a biomarker to assess MAO inhibition potential of new therapeutic agents.