title: An efficient post-hoc integration method improving peak alignment of metabolomics data from GCxGC/TOF-MS.
abstract: BACKGROUND
  Since peak alignment in metabolomics has a huge effect on the subsequent statistical analysis, it is considered a key preprocessing step and many peak alignment methods have been developed. However, existing peak alignment methods do not produce satisfactory results. Indeed, the lack of accuracy results from the fact that peak alignment is done separately from another preprocessing step such as identification. Therefore, a post-hoc approach, which integrates both identification and alignment results, is in urgent need for the purpose of increasing the accuracy of peak alignment.
  
  
  RESULTS
  The proposed post-hoc method was validated with three datasets such as a mixture of compound standards, metabolite extract from mouse liver, and metabolite extract from wheat. Compared to the existing methods, the proposed approach improved peak alignment in terms of various performance measures. Also, post-hoc approach was verified to improve peak alignment by manual inspection.
  
  
  CONCLUSIONS
  The proposed approach, which combines the information of metabolite identification and alignment, clearly improves the accuracy of peak alignment in terms of several performance measures. R package and examples using a dataset are available at http://mrr.sourceforge.net/download.html.
authors.affiliation: Department of Biostatistics, 410 West 10th st., Indianapolis, IN 46202, USA.
authors.forename: Jaesik
authors.initials: J
authors.lastname: Jeong
authors.forename: Xiang
authors.initials: X
authors.lastname: Zhang
authors.forename: Xue
authors.initials: X
authors.lastname: Shi
authors.forename: Seongho
authors.initials: S
authors.lastname: Kim
authors.forename: Changyu
authors.initials: C
authors.lastname: Shen
mesh_terms: D000465:Algorithms; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D055432:Metabolomics / Q000379:methods*; D051379:Mice
chemical_list: D015415:Biomarkers