title: Stability of ascorbic acid in serum and plasma prior to analysis.
abstract: BACKGROUND
  The stability of ascorbic acid in serum and plasma prior to analysis was studied.
  
  
  METHODS
  Blood samples were collected from ten healthy subjects into Vacutainer tubes containing either dipotassium EDTA, lithium-heparin or no additive. Ascorbic acid was analysed following immediate separation and preservation of samples, following delayed separation for 2 h and after delayed deproteinization and preservation for 2, 5 and 8 h. Deproteinization and preservation were achieved using a solution containing perchloric acid, EDTA and dithiothreitol. Ascorbic acid was analysed by high-performance liquid chromatography.
  
  
  RESULTS
  Blood collected into EDTA and separated, deproteinized and preserved immediately gave the highest yield of ascorbic acid. Loss of analyte after delayed separation was least for EDTA tubes (median 7%, range 4-13%), followed by lithium-heparin (median 18%, range 10-32%) and serum (median 26%, range 14-50%). Immediate separation of samples but delayed deproteinization and preservation also resulted in substantial losses of ascorbic acid.
  
  
  CONCLUSIONS
  Minimum loss of ascorbic acid is achieved if blood is collected into tubes containing dipotassium EDTA and separated within 2 h, followed by immediate deproteinization and preservation.
authors.affiliation: Clinical Pathology, Path Centre, Locked Bag 2009, Nedlands, Western Australia 6009, Australia.
authors.forename: Simon Y L
authors.initials: SY
authors.lastname: Ching
authors.forename: Alex W
authors.initials: AW
authors.lastname: Prins
authors.forename: John P
authors.initials: JP
authors.lastname: Beilby
mesh_terms: D000704:Analysis of Variance; D001205:Ascorbic Acid / Q000097:blood* / Q000737:chemistry / Q000378:metabolism; D001793:Blood Preservation / Q000379:methods; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004355:Drug Stability; D004492:Edetic Acid / Q000494:pharmacology; D006493:Heparin / Q000494:pharmacology; D006801:Humans; D013997:Time Factors
chemical_list: D006493:Heparin; D004492:Edetic Acid; D001205:Ascorbic Acid