Unit overview
The following slides describe what each unit covers
Isotopolearn
Welcome to Isotopolearn, a free, online resource for isotopologue education
This site is designed for investigators of all levels interested in isotopologue research.
No prior knowledge is assumed, but some familiarity with stable isotope geochemistry may help
Use the left-hand menu to navigate between units, or click the button below for more information.
I. Introduction
What it covers
Introduces the science of isotopologue research.
In this first section, we review the principles of isotopic fractionation, and highlight influential applications of isotopologue analyses in diverse fields, such as biogeochemistry, forensics, and space science.
Who it's for
Researchers of all levels with a background in (geo)chemistry but less familiarity with isotopologues, specifically.
Questions answered
- What's the difference between typical isotope ratio and isotopologue analyses?
- Which processes fractionate isotopologues?
- Why are isotopologues useful?
Learning outcomes
- Distinguish between bulk isotope and position-specific isotopologue ratio analyses
- Identify which position(s) within a molecule are most likely to be isotopically fractionated by a certain process
- Compute the randomized isotopologue distribution of a given compound
- Describe how deviations in isotopologue from a reference frame could be notated and visualized
- Summarize the kinds of questions that isotopologue analyses can help answer
II. Principles of Orbitrap analyses
What it covers
The principles of measuring site-specific isotopic abundances using Orbitrap mass spectrometry (Orbitrap MS). Oribtrap MS technologies have established uses in the identification of high molecular weight compounds, but only recently been applied to isotope ratios in natural abundances.
It focuses on the possibilities and limits of Orbitrap-based analyses and how they differ from conventional methods, to help PIs, project administrators, etc. evaluate the feasibility of new research projects.
Includes:
- How the instrument operates
- How to turn observations into constraints on the isotopic abundance of specific sites
- Strategies to change or enhance the distribution of desirable ion fragments
- Considerations for optimizing the efficiency of an orbitrap experiment
Who it's for
Principal investigators, graduate students, and postdocs who may be familiar with traditional IRMS techniques and are planning new projects
Learning outcomes
- Distinguish how an Orbitrap turns a reservoir of molecules into an observation of a mass spectrum vs. a conventional sector instrument
- Explain the user decision points and physical components that can change the range, relative abundance, and absolute intensity of the Orbitrap mass spectrum
- Describe how observations of isotope ratios of fragment ions can be converted into constraints on the isotopic abundance of specific molecular sites
- Describe two strategies to verify the identity of components of a molecular fragment ion
- Compute the most efficient workflow for reaching target precision.
- Evaluate whether a proposed analysis is feasible (given constraints of time, mass resolution, and complexity of the fragmentation spectrum), and identify potential failpoints.
III. Practice of Orbitrap analyses
What it covers
The practice of Orbitrap-based isotopologue analyses.
Using these instruments to make measurements tangential to their original purpose
is not straightforward.
Here we walk through the key methods for producing robust, high-quality data on these machines.
Who it's for
Researchers who make operate these instruments. Familiarity with Units I and II is assumed.
Learning outcomes
- Decide whether a target compound needs to be derivatized and/or purified prior to analysis, and consider the tradeoffs of certain derivatives over others
- Enumerate the components of a complete Orbitrap experiment
- Diagnose possible causes of an undesirable or anomalous instrument behavior
- Describe two strategies to verify the identity of components of a molecular fragment ion
- Describe the challenges of interlaboratory standardization of Orbitrap analyses, and propose three ways that relative isotopologue abundances could be converted into “absolute” isotopologue abundances
IV. Predicting isotopologue distributions
What it covers
Approaches to predicting isotopologue abundances with models. Comparing measurements with predictions is a tenet of evaluating scientific hypotheses. Computational techniques can create such predictions. Here, we overview such techniques.
Including:- Whole-molecule and position specific equilibrium assemblages
- Clumped isotope effects
- Kinetic istope effects
- Processes that moderate expression in multiphase systems, including
- Inheritance
- System openness
- Mass balance
- Reaction networks
Who it's for
Researchers who want to form hypotheses, predict outcomes, or build simple models to explain observations.
Learning outcomes
- ...
V. Bibliography
These materials are an overview, designed to be completed in hours, not days. For further reading on these topics we recommend:
- Papers here
Credits
Funding
This work was produced as part of ACIR, the Astrobiology Center for Isotopologue Research, a research center funded by NASA
Contributors
Many have contributed to this project, including
Authors
Beta testers
- your name here
Conception and Design
License
Distributed under the XXX license. All rights reserved.