We study the distribution, and chemical and stable isotope composition of organic molecules found in present-day and ancient environments to unravel the interplay between biology, biogeochemistry and climate. Our focus is on the structures, distributions, and stable isotope composition of cell membrane lipids (biomarkers) that can be identified in water bodies, sediments, soils, and their fossilized remains preserved in the rock record. 

Our lab is a shared analytical facility for multidisciplinary and collaborative research. We partner closely with several CU research groups:

 

Photo of Julio Sepúlveda

Julio Sepúlveda
Director

Photo of David Harning

David Harning
Postdoc

Photo of Jamie McFarlin

Jamie McFarlin
Postdoc

Photo of  Brooke Holman

Brooke Holman
Research staff

Photo of Harry Allbrook

Harry Allbrook
Grad student

Photo of Robert Kelleher

Robert Kelleher
Grad student

Silhouette of generic person

Christine Schlarbaum
Undergrad

  • Sebastian Cantarero, PhD, 2022
  • Garrett Boudinot, PhD Student
  • Steven Moran, UNAVCO-RESESS Summer Undergraduate Fellow. Wichita State University, Kansas (Summer 2017)
  • Michael "Avi" Gross, Undergraduate student, Geological Sciences and Chemistry (2015-2017)
  • Raman Umamaheswaran, Visiting Graduate Student, S.N. Bose Fellow, University of Delhi, India (Summer 2016)
  • Marwa Baroumi, Visiting Graduate Student, EAOG Fellow, University of Tunis El Manar, Tunisia (Fall 2015)

Contact

Julio Sepúlveda for lab and group inquires, including if you would like to join our group.   
Phone: 303-735-6877   SEEL room 214A 
Lab Phone: 303-735-3277   SEEL room 218


 Nadia Dildar (lab manager), Michael "Avi" Gross (undergraduate student), Aaron "Ari" Meilijson (postdoc), Julio Sepúlveda (PI), Garrett Boudinot (PhD student), Lina Pérez-Ángel (PhD student)

Organic Geochemistry Group Fall 2016/Spring 2017. From left to right: Nadia Dildar (lab manager), Michael "Avi" Gross (undergraduate student), Aaron "Ari" Meilijson (postdoc), Julio Sepúlveda (PI), Garrett Boudinot (PhD student), Lina Pérez-Ángel (PhD student)


Research

The Organic Geochemistry Group studies the interplay between microorganisms, biogeochemical processes, and climate in contemporary settings (e.g., continental margins, marine oxygen minimum zones, extreme environments), and paleo-ecosystems across major climatic/biotic transitions in Earth history (e.g., mass extinction events, greenhouse climates, glacial-interglacial transitions). We approach these systems with a focus on the structures, distributions, and stable isotope composition of cell membrane lipids (biomarkers) that can be identified in water bodies, sediments, soils, and their fossilized remains preserved in the rock record. 

Our research spans multiple disciplines:

  • Organic geochemistry and biomarkers
  • Stable isotope geochemistry
  • Geobiology and life in extreme environments
  • Paleoceanography
  • Paleoclimate
  • Chemical and biological oceanography

Photo of Julio Sepúlveda in the field, next to a outcrop and holding a sample

Julio Sepúlveda doing fieldwork.


Lab & facilities

The Organic Geochemistry Laboratory (OG Lab) at CU Boulder is a shared analytical facility for multidisciplinary and collaborative research in fields as diverse as biogeochemistry, geobiology, astrobiology, environmental microbiology, paleoceanography, paleoclimatology, and energy, among others.

    The OG Lab focuses on the extraction, purification, separation, and chemical and isotopic characterization of organic molecules extracted from a wide array of environmental and culture samples. Our state-of-the-art analytical facility, housed in the Sustainability, Energy and Environment Complex/Laboratories (SEEC/SEEL), began its operation in Summer 2016 and was specifically designed for research operations in organic geochemistry and compound-specific isotope ratio mass spectrometry.

    A Thermo Trace 1310 GC interphase to a Thermo Scientific TSQ 8000 EVO triple quadrupole MS allows for the separation, and the untargeted and targeted analysis of biomarkers using full scan and Selected Reaction Monitoring (SRM) modes. The high signal over ratio provided by SRM mode ensures a detection limit of ca. 0.5 fg on column, which is ideal for the analysis of samples with low organic content.

    A Thermo Finnigan Trace GC Ultra interphase to a PolarisQ ion-trap MS allows for the further characterization of biomarkers via MS-MS experiments. This instrument can also be attached to a Pyromat Curie-Point pyrolyzer (Brechbühler Scientific Analytical Solutions) for the analysis of bulk samples.

    A Hewlett Packard 6890 Gas GC with an FID allows for the separation and accurate quantification of organic molecules.

    A Thermo MAT 253 Plus isotope ratio mass spectrometer equipped with universal CNOS and HD collectors, ConfloIV interface, GC IsolinkII, and TraceGC1310 (GC-IRMS), allows for high sensitivity analysis of carbon and hydrogen stable isotopes of organic molecules. 

    A Thermo Scientific Ultimate 3000 HPLC interphase to a Q Exactive Focus Orbitrap-Quadrupole MS via electrospray ionization (ESI) or atmospheric pressure chemical ionization (APCI) allows for high sensitivity and high mass resolution for the targeted and untargeted analysis of polar biomarkers. Targeted analysis of polar lipids can be performed in Selected Ion Monitoring (SIM) and Parallel Reaction Monitoring (PRM) modes with high-resolution accurate-mass detection, and with enhanced signal over noise ratio for the detection of biomarkers present in low abundance. Untargeted analysis of unknown molecules can be performed via Full scan and Data-Independent Acquisition (DIA) modes. The Ultimate 3000 HPLC is also equipped with a DAD-3000 Diode Array Detector and a Fraction Collector for the identification, quantification, isolation and concentration of organic molecules for further chemical and/or stable isotope analysis.

    • Dionex 200 Accelerated Solvent Extraction (ASE) system
    • Anton Paar Multiwave 3000 Microwave Extraction System
    • Zymark Turbovap
    • Gilson GX-274 ASPEC Solid Phase Extraction system
    • Thermo Scientific Thermolyne Furnace Oven
    • Thermo Scientific Refrigerated Centrifuge
    • Freeze drier
    • Refrigerator and freezers
    • Microbalance and analytical balance

    Multiple lab vials held on a grid await measurement

    Publications

    Publications for Sepúlveda and Harning are shown below.  Additional publications are shown on McFarlin's Google Scholar profile.