title: The effects of pre-analysis sample handling on human plasma amino acid concentrations.
abstract: BACKGROUND
  The accurate and reliable quantification of amino acid concentrations in human plasma is important for the investigation of a number of diseases. However, few systematic studies investigating the changes in amino acid concentrations related to blood collection and storage conditions have been completed.
  
  
  METHODS
  Blood samples were collected with EDTA-Na2 from 3 healthy volunteers and subjected to a number of different treatments; hemolysis, temperature after blood collection, time from blood collection to cooling, the influence of platelets, long term storage conditions, and repeated freeze-thaw cycles. Changes in the concentrations of 22 amino acids were determined using an Amino Acid Analyzer.
  
  
  RESULTS
  Of the conditions influencing sample stability between blood collection and amino acid analysis, hemolysis, temperature after blood collection, and long-term storage at -20°C affected the concentrations of 11 amino acids. Time from blood collection to cooling, platelet contamination and repeated freeze-thaw cycles altered the levels of 4 amino acids.
  
  
  CONCLUSIONS
  We observed changes in amino acid concentrations relating to blood collection and storage conditions. If attention is paid to 4 key factors (hemolysis, temperature immediately following blood collection, time from collection to cooling, and long-term storage temperature) 19 amino acids can be reliably quantified.
authors.affiliation: Institute for Innovation, Ajinomoto Co., Inc., Japan.
authors.forename: Shunji
authors.initials: S
authors.lastname: Takehana
authors.affiliation: Institute for Innovation, Ajinomoto Co., Inc., Japan. Electronic address: hiroo_yoshida@ajinomoto.com.
authors.forename: Hiroo
authors.initials: H
authors.lastname: Yoshida
authors.affiliation: Institute for Innovation, Ajinomoto Co., Inc., Japan.
authors.forename: Shinichi
authors.initials: S
authors.lastname: Ozawa
authors.affiliation: Institute for Innovation, Ajinomoto Co., Inc., Japan.
authors.forename: Junko
authors.initials: J
authors.lastname: Yamazaki
authors.affiliation: Institute for Innovation, Ajinomoto Co., Inc., Japan.
authors.forename: Kazutaka
authors.initials: K
authors.lastname: Shimbo
authors.affiliation: Institute for Innovation, Ajinomoto Co., Inc., Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Nakayama
authors.affiliation: Institute for Innovation, Ajinomoto Co., Inc., Japan.
authors.forename: Toshimi
authors.initials: T
authors.lastname: Mizukoshi
authors.affiliation: Institute for Innovation, Ajinomoto Co., Inc., Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Miyano
mesh_terms: D000596:Amino Acids / Q000097:blood*; D006801:Humans; D010949:Plasma / Q000378:metabolism*; D013048:Specimen Handling; D013696:Temperature
chemical_list: D000596:Amino Acids
keywords: Amino acid; Plasma; Pre-analysis sample handling