title: Analyte stability during the total testing process: studies of vitamins A, D and E by LC-MS/MS.
abstract: BACKGROUND
  There are limited evidence based studies demonstrating the stability of fat-soluble vitamins (FSV) measured in blood. This study aimed to examine the effects of light, temperature and time on vitamins A, D and E throughout the total testing process.
  
  
  METHODS
  Four experiments were conducted. Three investigated the sample matrix, of whole blood, serum and the extracted sample, against the variables of temperature and light; and the fourth experiment investigated the sample during the extraction process against the variable of light. All samples were analysed via our simultaneous FSV method using liquid chromatography-tandem mass spectrometry technology. The allowable clinical percentage change was calculated based on biological variation and desirable method imprecision for each analyte. The total change limit was ±7.3% for 25-OH-vitamin D3, ±11.8% for retinol and ±10.8% for α-tocopherol.
  
  
  RESULTS
  Vitamins D and E were stable in the investigated conditions (concentration changes <4%) in the pre-analytical and analytical stages. Vitamin A showed photosensitivity in times >48 h with concentration changes of -6.8% (blood) and -6.5% (serum), both are within the allowable clinical percentage change. By contrast, the extracted retinol sample demonstrated a concentration change of -18.4% after 48 h of light exposure. However, vitamin A in the serum and extracted solution was stable for one month when stored at -20°C.
  
  
  CONCLUSIONS
  Blood samples for vitamins D and E analyses can be processed in normal laboratory conditions of lighting and temperature. The required conditions for vitamin A analysis are similar when performed within 48 h. For longer-term storage, serum and vitamin A extracts should be stored at -20°C.
authors.forename: Ali A
authors.initials: AA
authors.lastname: Albahrani
authors.forename: Victor
authors.initials: V
authors.lastname: Rotarou
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Roche
authors.forename: Ronda F
authors.initials: RF
authors.lastname: Greaves
mesh_terms: D000328:Adult; D001774:Blood Chemical Analysis / Q000592:standards*; D002853:Chromatography, Liquid / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D053719:Tandem Mass Spectrometry / Q000379:methods*; D014801:Vitamin A / Q000097:blood*; D014807:Vitamin D / Q000097:blood*; D014812:Vitamin K / Q000097:blood*; D014815:Vitamins / Q000097:blood*
chemical_list: D014815:Vitamins; D014801:Vitamin A; D014812:Vitamin K; D014807:Vitamin D