title: A QC approach to the determination of day-to-day reproducibility and robustness of LC-MS methods for global metabolite profiling in metabonomics/metabolomics.
abstract: BACKGROUND
  An approach to the determination of day-to-day analytical robustness of LC-MS-based methods for global metabolic profiling using a pooled QC sample is presented for the evaluation of metabonomic/metabolomic data. A set of 60 urine samples were repeatedly analyzed on five different days and the day-to-day reproducibility of the data obtained was determined. Multivariate statistical analysis was performed with the aim of evaluating variability and selected peaks were assessed and validated in terms of retention time stability, mass accuracy and intensity.
  
  
  RESULTS
  The methodology enables the repeatability/reproducibility of extended analytical runs in large-scale studies to be determined, allowing the elimination of analytical (as opposed to biological) variability, in order to discover true patterns and correlations within the data.
  
  
  CONCLUSIONS
  The day-to-day variability of the data revealed by this process suggested that, for this particular system, 3 days continuous operation was possible without the need for maintenance and cleaning. Variation was generally based on signal intensity changes over the 7-day period of the study, and was mainly a result of source contamination.
authors.affiliation: Department of Chemical Engineering, Aristotle University of Thessaloniki, 541 24, Greece.
authors.forename: Helen G
authors.initials: HG
authors.lastname: Gika
authors.forename: Georgios A
authors.initials: GA
authors.lastname: Theodoridis
authors.forename: Mark
authors.initials: M
authors.lastname: Earll
authors.forename: Ian D
authors.initials: ID
authors.lastname: Wilson
mesh_terms: D056148:Chromatography, Reverse-Phase / Q000379:methods*; D003627:Data Interpretation, Statistical; D005260:Female; D006801:Humans; D008297:Male; D055442:Metabolome; D055432:Metabolomics / Q000379:methods*; D008875:Middle Aged; D011786:Quality Control; D012015:Reference Standards; D015203:Reproducibility of Results; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D014556:Urine / Q000737:chemistry