Stability of Plasma Free Metanephrines during Collec- tion and Storage as Assessed by an Optimized HPLC

tion and Storage as Assessed by an Optimized HPLC Method with Electrochemical Detection, Jacques J. Willemsen, C.G.J. (Fred) Sweep, Jacques W.M. Lenders, and H. Alec Ross (Departments of 1 Chemical Endocrinology, 2 General Internal Medicine, and 3 Endocrinology, University Medical Center Nijmegen, 6500 HB Nijmegen, The Netherlands; * address correspondence to this author at: Department of Chemical Endocrinology 530, University Medical Center Nijmegen, PO Box 9101, 6500 HB Nijmegen, The Netherlands; fax 31-24-3541484, e-mail a.ross@ ace.umcn.nl)