Compound specific isotope analysis CSIA

Compound-specific isotope analysis (CSIA) by GC-IRMS became possible in 1978 due to work of Mathews and Hayes [634], based on earlier low-precision work of Sano et al. [635]. The key innovation was the development of a catalytic combustion furnace based on Pt with CuO as oxygen source, placed between the GC exit and the mass spectrometer. The high pressure of helium (99.999% purity or better) ensures that all gas flows are viscous. After being dried in special traps avoiding formation of HC02 (i. e., interferes with 13C02) by ion-molecule reactions in the ion source, the C02 is transmitted to a device that regulates pressure and flow and then into the ion source [604]. 

Newer instrumental methods of potential utility in organic analysis of environmental and geological biomarkers are compound specific isotope analysis (CSIA) and carbon-14 dating with accelerator mass spectrometry (AMS). CSIA provides the carbon isotope composition of individual... 

Figure 9.50a Compound-specific isotope analysis (CSIA) of suspended particulate organic matter (SPOM), lipids, and plant pigments in several estuaries on the Texas coast (USA). The range of 513C in these estuaries was —18 %o to —22 %o. (Modified from Qian et al., 1996.)...

Sources of PAHs can be distinguished by using select ratios. For example, ratios of total methylphenanthrenes to phenanthrene is used to identify PAHs as pyrolytic or petrogenic sources. Other work has resorted to the application of compound-specific isotope analysis (CSIA), to constrain better anthropogenic sources of PAHs. 

The aim of this review is to provide a critical evaluation of recently published analytical methods available for (i) the quantification of fuel oxygenates in environmental aqueous samples and (ii) the characterization of the environmental fate of MTBE in groundwater with the use of compound-specific isotope analysis (CSIA). For a detailed evaluation of methods available for air, water and soil analysis of dialkyl ethers and alcohols and their specific advantages and drawbacks, the reader is also referred to previous reviews. [3-6]. 

Compound-specific isotope analysis (CSIA) is a rather new tool in environmental analysis. It is not used for quantitative analysis of organic compoimds but rather for the characterization of environmental fate by monitoring changes in the isotopic composition of organic molecules. Analytical aspects are covered here because this rather new area of research is expected to mature to a standard tool in environmental analysis that will complement the quantitative analysis in the environment [70]. 

Compound-specific isotope analysis (CSIA) enables the carbon isotopic analyses of individual compounds to be determined as they elute from a GC column [70,71]. 

The compound specific isotope analysis (CSIA) has been successfully used in the assessment of in situ remediation of contaminated environments, identification of pollutant degradation pathways, or the verification of contaminant sources. In these types of studies, the sensitivity of isotope ratio monitoring GC-MS (irm-GC-MS) is often a limiting factor, since concentrations of organic contaminants in groundwater are very often in the low pg/L range. Hence, in order to be able to routinely use irm-GC-MS techniques in environmental studies, efficient extraction procedures are required. 

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