CSIA
Compound-specific isotope analysis (CSIA) is a stable isotope analysis technique developed in the 1990s. The method can separate organic analytes from complex mixtures and then determine the composition and variation characteristics of individual stable isotope ratios at natural isotopic abundances to identify the source of organic pollutants, clarify the migration and transformation process of organic pollutants in the environment, and finally realize the goal of monitoring and prevention of organic pollutants in the environment.
Alfa Chemistry has global experimental and analysis abilities based on our comprehensive technical platforms and professional R&D team. We can provide you with rigorous CSIA experimental to solve any environmental pollution problem you met.
Principle of CSIA
CSIA mainly uses gas chromatography (GC) or liquid chromatography (LC) to separate the target organic matter from the mixture to obtain a single compound, and then determines the stable isotope ratio of elements in the single compound by isotope ratio mass spectrometer [1] (as shown in Fig. 1). The quotient between the heavy and the light isotope is called stable isotope ratio (i.e., stable isotope composition) or isotope signature (e.g., 13C/12C, 2H/1H), usually expressed by R. Because the R value is extremely low and very difficult to accurately measure in actual. So, it is expressed as delta notation (δ) relative to an international standard according to the following formula.
Where R1 and R0 are the isotope ratios of the sample and an international standard, respectively.
Fig. 1. The principle of CSIA by chromatography–IRMS.
Alfa Chemistry's CSIA Service Items
| Items | Main content |
|---|
| Origin traceability of organic contaminants | Origin traceability of halohydrocarbons, polycyclic aromatic hydrocarbons (PAHs), methyl tert-butyl ether (MTBE), pesticide (organophosphorus pesticides, organochlorine pesticides, etc.) and many others |
| Transformation processes of organic contaminants | 1. Calculation of isotope enrichment coefficient
2. Assessment of contaminant sites
3. Analyze the different reaction paths of contaminants
... |
| Evaluating degradation of organic contaminants | 1. Multielement CSIA for differentiation of degradation pathways
2. Detection and quantification of organic contaminants degradation
3. Field studies
... |
| ... | ... |
※ The above items are only part of the test items in Alfa Chemistry. Please contact us for more service information.
Alfa Chemistry's CSIA Instrument Platform
- GC–IRMS: Gas chromatography–isotope-ratio mass spectrometry
※ The GC–IRMS includes GC-C-IRMS and GC-TC-IRMS, in which GC-C-IRMS can measure the isotopic composition of carbon element in monomer, while GC-TC-IRMS can measure the isotopic composition of hydrogen element.
- LC–IRMS: Liquid chromatography–isotope-ratio mass spectrometry
- DI-GC-IRMS: Direct induction-gas chromatography-isotope ratio mass spectrometry
Fig. 2. The system of (A) GC-IRMS and (B) LC-IRMS.
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Reference
- Elsner M., et al. Current challenges in compound-specific stable isotope analysis of environmental organic contaminants[J]. Analytical and bioanalytical chemistry, 2012, 403(9): 2471-2491.
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