title: Quantitation of total biopterin and tetrahydrobiopterin in plasma.
abstract: OBJECTIVE
  To develop a reliable method for the determination of tetrahydrobiopterin and total biopterin in plasma.
  
  
  METHODS
  Modifications include blood collection and handling procedures.
  
  
  RESULTS
  Collection of blood in the presence of 0.1% (w/v) dithiothreitol and waiting for 2-3 h before centrifugation are optimal for adequate quantitation of both pterins.
  
  
  CONCLUSIONS
  For a reliable determination of tetrahydrobiopterin and total biopterin in plasma, blood tubes must contain a dimercapto-antioxidant and time between blood collection and centrifugation is critical.
authors.affiliation: Department of Neuroscience, Laboratory of Neurobiology, Room Ee 1438, Erasmus MC, P.O. Box 1738, 3000 DR Rotterdam, The Netherlands. d.fekkes@erasmusmc.nl
authors.forename: Durk
authors.initials: D
authors.lastname: Fekkes
authors.forename: Ans
authors.initials: A
authors.lastname: Voskuilen-Kooijman
mesh_terms: D001708:Biopterins / Q000031:analogs & derivatives* / Q000097:blood; D002851:Chromatography, High Pressure Liquid; D005260:Female; D006801:Humans; D008297:Male; D011622:Pterins / Q000097:blood*; D015203:Reproducibility of Results
chemical_list: D011622:Pterins; D001708:Biopterins; C003402:sapropterin