Synchrotron-Based Mass Spectrometry to Investigate the Molecular Properties of Mineral鈥揙rganic Associations

详细信息    查看全文

• 作者：Suet Yi Liu ; Markus Kleber ; Lynelle K. Takahashi ; Peter Nico ; Marco Keiluweit ; Musahid Ahmed
• 刊名：Analytical Chemistry
• 出版年：2013
• 出版时间：June 18, 2013
• 年：2013
• 卷：85
• 期：12
• 页码：6100-6106
• 全文大小：377K
• 年卷期：v.85,no.12(June 18, 2013)
• ISSN：1520-6882

文摘

Soil organic matter (SOM) is important because its decay drives life processes in the biosphere. Analysis of organic compounds in geological systems is difficult because of their intimate association with mineral surfaces. To date there is no procedure capable of quantitatively separating organic from mineral phases without creating artifacts or mass loss. Therefore, analytical techniques that can (a) generate information about both organic and mineral phases simultaneously and (b) allow the examination of predetermined high-interest regions of the sample as opposed to conventional bulk analytical techniques are valuable. Laser desorption synchrotron postionization (synchrotron-LDPI) mass spectrometry is introduced as a novel analytical tool to characterize the molecular properties of organic compounds in mineral鈥搊rganic samples from terrestrial systems, and it is demonstrated that, when combined with secondary ion mass spectrometry (SIMS), it can provide complementary information on mineral composition. Mass spectrometry along a decomposition gradient in density fractions verifies the consistency of our results with bulk analytical techniques. We further demonstrate that, by changing laser and photoionization energies, variations in molecular stability of organic compounds associated with mineral surfaces can be determined. The combination of synchrotron-LDPI and SIMS shows that the energetic conditions involved in desorption and ionization of organic matter may be a greater determinant of mass spectral signatures than the inherent molecular structure of the organic compounds investigated. The latter has implications for molecular models of natural organic matter that are based on mass spectrometric information.