A new maximum likelihood approach with asymmetric residual distribution for multicomponent mass spectra analysis

Eur. J. Mass Spectrom. 10, 573–578 (2004)
DOI: 10.1255/ejms.672

A new maximum likelihood approach with asymmetric residual distribution for multicomponent mass spectra analysis

Jukka Heikkonen,^a,* Jouni Juujarvi,^a,f Marianna Ridderstad,^bTapio Kotiaho,^c Raimo A. Ketola^d and Virpi Tarkiainen^e
^aHelsinki University of Technology, Laboratory of Computational Engineering, PO Box 9203, FIN-02015 Hut, Finland. E-mail: jukka.heikkonen@hut.fi, jouni.juujarvi@codator.fi
^bHelsinki University, Observatory, University of Helsinki, Tahtitorninmaki, PO Box 14, FIN-00014, Finland. E-mail: marianna@astro.helsinki.fi
^cUniversity of Helsinki, Laboratory of Analytical Chemistry, Department of Chemistry, University of Helsinki, A.I. Virtasen aukio 1, PO Box 55, FIN-00014, Finland. E-mail:tapio.kotiaho@helsinki.fi
^dUniversity of Helsinki, Drug Discovery Technology Center DDTC, Department of Pharmacy, University of Helsinki, PO Box 56, Viikinkaari 5E, FIN-00014 Finland. E-mail: raimo.ketola@helsinki.fi
^eTechnical Research Centre of Finland, VTT ProcessesBiologinkuja 7, P.O.Box 1602, FIN-02044 VTT, Finland. E-mail: virpi.tarkiainen@vtt.fi

ABSTRACT:

This paper proposes a new maximum likelihood approach for the deconvolution of identity and quantity of individual compounds based on the multicomponent mass spectra measured by mass spectrometry (MS). Mixture analysis of multicomponent mass spectra is, typically, based on a linear multicomponent mass spectrum model, where the compounds of the measured spectra to be solved are explicitly stated and assumed to be known. In many cases, however, the measured spectrum may contain unknown compounds that are not explicitly stated in the model and a commonly used least square (LS) solution fails. Moreover, a standard improvement over the LS method in these cases, namely the M-estimation (ME) approach, also suffers from this same problem. Our method overcomes the limitations of the LS and ME methods by modeling the effect of the unknown compound(s) to the residual of the linear model. The experimental results presented show that this new approach can separate more robustly the complex multicomponent mass spectra into their individual constituents compared to the LS and ME methods.

Keywords: mass spectrometry, analysis of volatile compounds, mixture analysis, deconvolution, maximum likelihood

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