Gas Chromatography Coupled to High Resolution Time-of-Flight Mass Spectrometry as a High-Throughput Tool for Characterizing Geochemical Biomarkers in Sediments

Author(s)

Ferreira Koolen, Hector Henrique ; Klitzke, Clecio Fernando ; Binkley, Joe ; Patrick, Jeffrey ; Rizatti de Albergaria-Barbosa, Ana Cecilia ; Weber, Rolf Roland ; Bicego, Marcia Caruso ; Eberlin, Marcos Nogueira ; Bataglion, Giovana Anceski

• Document type: Journal article
• Source: INTERNATIONAL JOURNAL OF ANALYTICAL CHEMISTRY; v. 2018, p. 10-pg., 2018-01-01.

Abstract

The performance of gas chromatography coupled to high-resolution time-of-flight mass spectrometry (GC-HRTofMS) for characterizing geochemical biomarkers from sediment samples was evaluated. Two approaches to obtain the geochemical biomarkers were tested: (1) extraction with organic solvent and subsequent derivatization and (2) in-situ derivatization thermal desorption. Results demonstrated that both approaches can be conveniently applied for simultaneous characterization of many geochemical biomarkers (alkanes, alkanols, sterols, and fatty acids), avoiding conventional time-consuming purification procedures. GC-HRTofMS reduces both sample preparation time and the number of chromatographic runs compared to traditional methodologies used in organic geochemistry. Particularly, the approach based on in-situ derivatization thermal desorption represents a very simple method that can be performed in-line employing few milligrams of sediment, eliminating the need for any sample preparation and solvent use. The high resolving power (m/m(50%) 25,000) and high mass accuracy (error 1 ppm) offered by the zig-zag time-of-flight analyzer were indispensable to resolve the complexity of the total ion chromatograms, representing a high-throughput tool. Extracted ion chromatograms using exact m/z were useful to eliminate many isobaric interferences and to increase significantly the signal to noise ratio. Characteristic fragment ions allowed the identification of homologous series, such as alkanes, alkanols, fatty acids, and sterols. Polycyclic aromatic hydrocarbons were also identified in the samples by their molecular ions. The characterization of geochemical biomarkers along a sedimentary core collected in the area of Valo Grande Channel (Cananeia-Iguape Estuarine-Lagunar System (SAo Paulo, Brazil)) provided evidences of environmental changes. Sediments deposited before opening of channel showed dominance of biomarkers from mangrove vegetation, whereas sediments of the pos-opening period showed an increase of biomarkers from aquatic macrophyte (an invasive vegetation). (AU)

• FAPESP's process: 12/21395-0 - Molecular characterization of sedimentary organic matter in the Estuary-Lagoon System Cananéia-Iguape by Fourier transform ion cyclotron resonance mass spectrometry
• Grantee: Giovana Anceski Bataglion
• Support Opportunities: Scholarships in Brazil - Doctorate