Jeannette Klein studied Chemistry at Humboldt University Berlin and received her PhD in Analytical Chemistry. With her experiences in LC-MS/MS techniques acquired in pesticide residue analysis she established the technical basis for the extended Newborn Screening by Tandem Mass Spectrometry at the Newborn Screening Laboratory in Berlin. For more than 20 years, she is working as technical lab manager in both the Newborn Screening and the Metabolic Lab, interested in the application of mass spectrometry to the clinical diagnostics of inborn errors of metabolism and endocrinopathies.