Heart-cutting two-dimensional gas chromatography-isotope ratio mass spectrometry analysis of monoaromatic hydrocarbons in complex groundwater and gas-phase samples
Violaine Ponsin, Timothy E. Buscheck & Daniel Hunkeler
| Résumé |
Compound-specific isotope analysis (CSIA) is increasingly used to
evaluate the origin and fate of petroleum hydrocarbons in the
environment. However, as samples often contain a complex mixture of
compounds and the method requires a full chromatographic separation,
it can be challenging to obtain accurate and precise isotope values.
In this study, in order to develop a method to analyze carbon
isotopes in benzene, toluene, ethylbenzene, and xylenes (BTEX) in
complex environmental samples, a two-dimensional heart-cutting gas
chromatograph (GC) was hyphenated to an isotope ratio mass
spectrometer (IRMS). The focus was placed on benzene and toluene,
which are the main compounds of concern in contaminated sites. A
full separation for BTEX was successfully achieved using a 60m
polar column in the first dimension and a 30m non-polar column in
the second dimension. Accuracy and precision of carbon isotope
measurements of standards were not impacted by the new setup
compared to classic one-dimensional (1D) GC-C-IRMS. For benzene and
toluene, precision remained very good (≤0.2‰) for
concentrations comprised between 5 and 20μg/L. A high matrix
load did not influence the precision and accuracy of isotope
measurements. The method was tested on several samples from two
different field sites. For all samples tested, full chromatographic
baseline resolution was achieved for benzene and toluene. Spatial
variability of isotopes values linked to biodegradation was
evidenced for one field site. This new 2D-GC-C-IRMS method will
broaden the spectrum of samples suitable for isotope analysis and
will be therefore able to give new insights into attenuation
processes of BTEX in contaminated sites or source
fingerprinting. |
| Mots-clés |
BTEX; Heart-cutting; Isotope ratio mass spectrometry; Multidimensional GC; Stable isotope. |
| Citation | Ponsin, V., Buscheck, T. E., & Hunkeler, D. (2017). Heart-cutting two-dimensional gas chromatography-isotope ratio mass spectrometry analysis of monoaromatic hydrocarbons in complex groundwater and gas-phase samples. Journal of Chromatography A, 1492, 117-128. |
| Type | Article de périodique (Anglais) |
| Date de publication | 2-2017 |
| Nom du périodique | Journal of Chromatography A |
| Volume | 1492 |
| Pages | 117-128 |
| URL | http://dx.doi.org/10.1016/j.chroma.2017.02.060 |