Isotope Ratio Mass Spectrometry
Isotope Ratio Mass Spectrometry - Related Videos
01:13
Mass Spectrometry: Isotope Effect
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2025
Most elements exist in nature as a mixture of isotopes. The isotopes differ in weight due to their respective number of neutrons. The molecular weight of a molecule is different depending on the specific isotope of its elements involved. As a result, the mass spectrum of the molecule exhibits peaks from the same fragment at multiple positions. The positions of these mass signals depend on the mass differences between isotopes. Furthermore, the intensity of these signals is dependent on the...
12:07
Profiling Thiol Redox Proteome Using Isotope Tagging Mass Spectrometry
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Cited by 50 •
2012
Reactive oxygen species level is elevated when cells encounter stress conditions. Here we show the example of 3'-3' diaminobenzidine staining as well as cysTMT labeling and mass spectrometry to profile the redox proteome in Pseudomonas syringae treated tomato leaves.
13:45
Introduction to Mass Spectrometry
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2023
Source: Laboratory of Dr. Khuloud Al-Jamal - King's College London Mass spectrometry is an analytical chemistry technique that enables the identification of unknown compounds within a sample, the quantification of known materials, the determination of the structure, and chemical properties of different molecules. A mass spectrometer is composed of an ionization source, an analyzer, and a detector. The process involves the ionization of chemical compounds to generate ions. When using...
09:26
Cellular Lipid Extraction for Targeted Stable Isotope Dilution Liquid Chromatography-Mass Spectrometry Analysis
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Cited by 6 •
2011
This protocol will demonstrate the extraction and analysis of free and esterified bioactive fatty acids from cells. Fatty acids are accurately quantified using stable isotope dilution, chiral liquid chromatography, electron capture atmospheric chemical ionization multiple reaction monitoring mass spectrometry (SID-LC-ECAPCI-MRM/MS).
07:09
Tandem Mass Spectrometry
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2023
In tandem mass spectrometry a biomolecule of interest is isolated from a biological sample, and then fragmented into multiple subunits in order to help elucidate its composition and sequence. This is accomplished by having mass spectrometers in series. The first spectrometer ionizes a sample and filter ions of a specific mass to charge ratio. Filtered ions are then fragmented and passed to a second mass spectrometer where the fragments are analyzed. This video introduces the principles of...
FAQs
Reference standards provide the comparison needed to convert isotope ion signals into precise ratios. By evaluating a sample against an established reference, researchers can distinguish meaningful differences in relative isotope abundance from variation caused by measurement conditions. This makes results more consistent across environmental samples and supports interpretation of source or process patterns.
Ionization allows purified compounds or elements to enter the instrument as measurable ions. The system then separates those ions according to mass-to-charge ratio, enabling individual isotope signals to be compared. This sequence is essential because the environmental interpretation depends on resolving isotope-specific signals rather than treating the sample as a single undifferentiated chemical measurement.
Differences in isotope ratios can provide evidence that materials came from different sources or experienced different transformations. In environmental studies, these patterns may indicate evaporation, nutrient cycling, microbial degradation, or movement through ecological systems. Interpretation relies on comparing the measured pattern with reference information and the environmental setting rather than considering a ratio in isolation.
A typical workflow begins with obtaining a relevant environmental sample and purifying the compound or element of interest. The purified material is introduced into the instrument, converted into ions, and separated by mass-to-charge ratio. Researchers then compare the resulting isotope ion signals with reference standards to calculate ratios suitable for environmental interpretation.
The technique is useful when investigators need evidence linking environmental contamination to particular material sources. Measurements of isotope patterns in relevant samples can help distinguish source contributions and provide context for how pollutants move or change. This source-tracing capability supports environmental assessments involving water, soil, atmospheric materials, and ecological systems.
Measurements of carbon, nitrogen, hydrogen, and oxygen isotope ratios can follow these elements through water, soil, atmospheric, and ecological systems. The resulting patterns help researchers examine material movement and biogeochemical transformations, including nutrient cycling and microbial degradation. They can also contribute to reconstructing past environmental conditions when isotope evidence is interpreted within the relevant system.