Patricia M. Medeiros 1, 2 Bernd R. T. Simoneit 1, 2, 3 1 Environmental Science Program, Oregon State University, Corvallis, USA 2 Environmental and Petroleum Research Group, College of Oceanic and Atmospheric Sciences, Oregon State University, Corvallis, USA 3 Department of Chemistry, College of Science, Oregon State University, Corvallis, USA Review Gas chromatography coupled to mass spectrometry for analyses of organic compounds and biomarkers as tracers for geological, environmental, and forensic research Gas chromatography, especially when coupled with mass spectrometry, is the analy- tical method of choice for elucidation of biomarker compounds present in organic mixtures extracted from geological, environmental, and biological samples. This review describes the biomarker concept, i. e., the precursor natural products to the geological/environmental derivatives, and their application as multi-tracers in the geosphere and ambient environment. The mass spectrometric methods currently utilized for such analyses are reviewed with a general key to the literature, and typi- cal examples of applications using GC – MS are also described. Keywords: Biomarkers / Environmental and forensic chemistry / GC – MS / Geochemistry / Received: October 1, 2006; revised: March 20, 2007; accepted: March 22, 2007 DOI 10.1002/jssc.200600399 1 Introduction Tracer analysis using molecular markers has its origin in fossil fuel geochemistry, where Treibs [1] showed the link between chlorophyll-a in living photosynthetic organ- isms and porphyrins in petroleum and shales, thus pro- viding the first strong evidence for an organic origin of petroleum. The term “biomarker” evolved from early product-precursor relationships and was proposed in the 1960s [2]. Biomarkers are defined here as compounds derived from biological sources (i. e., natural products) that retain some, if not all, of the structural characteris- tics of their parent precursor molecule after being pre- served in the geological record or released into the envi- ronment. Hence, they can be traced back to their biologi- cal origin. The relevance of those naturally derived satur- ated and aromatic hydrocarbons (and sometimes oxygen- ated analogs) to environmental geochemistry became evident when polynuclear aromatic hydrocarbons (PAHs) of anthropogenic or geogenic origin were found in recent and contemporary sediments [3 – 6]. In the geolog- ical record, the biomarkers were originally called chemi- cal fossils [7 – 9], and the concept has been extended to environmental chemistry [10, 11]. Note that the term “biomarker” as used in the biological sciences has differ- ent meanings to that in geochemistry. In toxicology, for instance, biomarkers are components in biological flu- ids, cells, tissues, or whole organisms that indicate the presence, magnitude, and exposure of toxicants or of host response [11]. Structure elucidations by classical methods and later by mass spectrometry of natural products were carried out by organic chemists during the 1950 – 1970s. The mass spectra were generally determined with low- and high-resolution instruments for the underivatized natu- ral product or its acetate ester (also methyl ethers). The coupling of gas chromatography with mass spectrometry (GC – MS) was the major breakthrough in developing bio- marker geochemistry initially for petroleum exploration research and then for organic geochemistry in general [12]. Current instrumentation and derivatization meth- ods (especially silylation of polar functional groups) extended the biomarker concept into other disciplines and applications where hydrocarbons and polar, as well as synthetic (anthropogenic) compounds are encoun- tered. Biomarker elucidation and utilization is currently being pursued in the pharmaceutical and food indus- tries, and will provide novel biomarkers of geochemical and environmental interest. However, the classical natu- ral product database and standards are of greatest utility for environmental biomarker research. Correspondence: Dr. Patricia M. Medeiros. Present address: In- stitute of Marine and Coastal Sciences, Rutgers University, 71 Dudley Road, New Brunswick, NJ 08901, USA E-mail: medeiros@marine.rutgers.edu Fax: +1 732 932-8578 Abbreviations: DOM, dissolved organic matter; PAH, polynu- clear aromatic hydrocarbons; PLFA, phospholipid fatty acids; POM, particulate organic matter; SOM, sedimentary organic matter; TOM, terrestrial organic matter i 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.jss-journal.com 1516 P. M. Medeiros and B. R. T. Simoneit J. Sep. Sci. 2007, 30, 1516 – 1536