Sahlgrenska Academy at University of Gothenburg, Sahlgrenska University Hospital 1 article published in JoVE Medicine Absolute Quantification of Aβ1-42 in CSF Using a Mass Spectrometric Reference Measurement Procedure Josef Pannee1,2, Kaj Blennow1,2, Henrik Zetterberg1,2,3, Erik Portelius1,2 1Institute of Neuroscience and Physiology, Department of Psychiatry and Neurochemistry, The Sahlgrenska Academy at University of Gothenburg, Sahlgrenska University Hospital, 2Clinical Neurochemistry Laboratory, Sahlgrenska University Hospital, 3UCL Institute of Neurology, Queen Square A reference measurement procedure for the absolute quantification of Aβ1-42 in human CSF based on solid-phase extraction and liquid chromatography tandem mass spectrometry is described.