To cite the IPO package in publications use:

  Libiseller, Dvorzak, Kleb, Gander, Eisenberg, Madeo, Neumann,
  Trausinger, Sinner, Pieber, Magnes IPO: A Tool for automated
  Optimization of XCMS Parameters BMC Bioinformatics (accepted)

A BibTeX entry for LaTeX users is

  @Article{,
    author = {Gunnar Libiseller and Michaela Dvorzak and Ulrike Kleb and Edgar Gander and Tobias Eisenberg and Frank Madeo and Steffen Neumann and Gert Trausinger and Frank Sinner and Thomas Pieber and Christoph Magnes},
    title = {IPO: a tool for automated optimization of XCMS parameters},
    journal = {BMC Bioinformatics},
    year = {(2015)},
    volume = {16},
    pages = {118},
  }