Prev. Article Table of Contents

Small Correspondence

Fundamentals of Molecular Formula Assignment to Ultrahigh Resolution Mass Data of Natural Organic Matter

Supporting Info

Boris P. Koch,*^† Thorsten Dittmar,^‡ Matthias Witt,^§ and Gerhard Kattner^†

Department of Chemical Ecology, Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany, Department of Oceanography, Florida State University, OSB 311, Tallahassee, Florida 32306-4320, and Bruker Daltonik GmbH, Fahrenheitstrasse 4, 28359 Bremen, Germany

Anal. Chem., 2007, 79 (4), pp 1758–1763

DOI: 10.1021/ac061949s

Publication Date (Web): January 9, 2007

Corresponding author. Phone: +49 471 4831 1346. Fax: +49 471 4831 1425. E-mail: bkoch@awi-bremerhaven.de.

†

Alfred Wegener Institute for Polar and Marine Research.

‡

Florida State University.

Bruker Daltonik GmbH.

Abstract

Ultrahigh-resolution mass spectrometry via the Fourier transform ion cyclotron resonance technique (FT-ICR-MS) allows the identification of thousands of different molecular formulas in natural organic matter and petroleum samples. Molecular formula assignment from mass data is most critical and time-consuming for these samples, and in many cases, several formulas can be determined for the same molecular mass. Therefore, automated procedures are required for an efficient exploitation of the extensive data sets. Here, we revise statements in a recent publication,¹ which might result in a misleading impression about our approach of formula assignment in a previous work. We also summarize and categorize existing procedures for formula assignment. In addition, we propose new techniques, which are suitable to be implemented in automated evaluation software. The homologous series approach is extended toward a building block approach that can be applied as a new exclusion criterion for incorrect formula assignments. The examination of stable isotope ratios of individual molecules in natural organic matter can be applied as an additional and intrinsic evaluation for calculated molecular formulas.

View: Full Text HTML | Hi-Res PDF