ABSTRACT Accuracy is the most important issue when performing compound-specific stable isotope an... more ABSTRACT Accuracy is the most important issue when performing compound-specific stable isotope analysis of polycyclic aromatic hydrocarbons (PAHs) extracted from complex samples. It depends on two main factors: the possible isotopic fractionation of the compounds during extraction and the potential co-elution with interfering compounds with different isotopic signatures. Herein, a simplified pressurised liquid extraction method for compound-specific stable isotope analysis of PAHs in non-aqueous-phase liquids of coal tar is presented. Samples extracted using the new method and by fractionation on a silica gel column were analysed by comprehensive two-dimensional gas chromatography. It was possible to evaluate the effect of co-elution on the carbon and hydrogen stable isotope signatures of the 16 US EPA priority PAHs in coal tars with various proportions of aromatic and aliphatic content. Even in samples that presented a good baseline resolution, the PAHs of interest co-eluted with other aromatic compounds with a notable effect on their stable isotope values; this demonstrated the necessity to check the quality of all extraction and clean-up methods (either the simplified pressurised liquid extraction or more traditional labour-intensive methods) for more complex samples prior to data interpretation. Additionally, comprehensive two-dimensional gas chromatography enabled visualisation of the suspected co-elution for the first time.
A GC × GC-TOFMS installed with a Rtx-PCB (60 m × 0.18 mm × 0.18 μm) in the first dimension and Rx... more A GC × GC-TOFMS installed with a Rtx-PCB (60 m × 0.18 mm × 0.18 μm) in the first dimension and Rxi- 17 (1.5 m × 0.1 mm × 0.1 μm) column in the second dimension was used to separate 188 out of 209 congeners. A further 12 congeners were identified through additional data processing resulting in the identification of a total of 200 congeners. However, caution is advised if these 12 congeners were to be used in quantitative assessments. The remaining 9 co-eluting congeners were three doublets (CB65 + CB62, CB160 + CB163 and CB201 + CB204) and one triplet (CB20 + CB21 + CB33). This method was tested on five Aroclors and resulted in the separation of all congeners present in the heavier Aroclor mixtures A1254 and A1260. The suitability of this method for applications in biological matrices was demonstrated on extracted whiting and guillemot liver samples which resulted in the identification of 137 individual PCBs in the whiting liver sample and 120 in the guillemot sample. Fingerprinting ...
In the second half of the twentieth century, increasing efforts were made towards containing and ... more In the second half of the twentieth century, increasing efforts were made towards containing and cleaning contaminated groundwater. A number of techniques can be used to achieve such goals, traditionally either by treating or isolating the soil in situ, or by removing it for washing or disposal. However, such technologies tend to be accompanied by high energy consumption, and can lead to new environmental problems. Therefore, more efficient and economical techniques are needed to remediate contaminated soil and groundwater. ...
Reductive dechlorination of trichloroethene (TCE) by zero-valent iron produces a systematic enric... more Reductive dechlorination of trichloroethene (TCE) by zero-valent iron produces a systematic enrichment of 13C in the remaining substrate that can be described using a Rayleigh model. In this study, fractionation factors for TCE dechlorination with iron samples from two permeable reactive barriers (PRBs) were established in batch experiments. Samples included original unused iron as well as material from a barrier
ABSTRACT Accuracy is the most important issue when performing compound-specific stable isotope an... more ABSTRACT Accuracy is the most important issue when performing compound-specific stable isotope analysis of polycyclic aromatic hydrocarbons (PAHs) extracted from complex samples. It depends on two main factors: the possible isotopic fractionation of the compounds during extraction and the potential co-elution with interfering compounds with different isotopic signatures. Herein, a simplified pressurised liquid extraction method for compound-specific stable isotope analysis of PAHs in non-aqueous-phase liquids of coal tar is presented. Samples extracted using the new method and by fractionation on a silica gel column were analysed by comprehensive two-dimensional gas chromatography. It was possible to evaluate the effect of co-elution on the carbon and hydrogen stable isotope signatures of the 16 US EPA priority PAHs in coal tars with various proportions of aromatic and aliphatic content. Even in samples that presented a good baseline resolution, the PAHs of interest co-eluted with other aromatic compounds with a notable effect on their stable isotope values; this demonstrated the necessity to check the quality of all extraction and clean-up methods (either the simplified pressurised liquid extraction or more traditional labour-intensive methods) for more complex samples prior to data interpretation. Additionally, comprehensive two-dimensional gas chromatography enabled visualisation of the suspected co-elution for the first time.
A GC × GC-TOFMS installed with a Rtx-PCB (60 m × 0.18 mm × 0.18 μm) in the first dimension and Rx... more A GC × GC-TOFMS installed with a Rtx-PCB (60 m × 0.18 mm × 0.18 μm) in the first dimension and Rxi- 17 (1.5 m × 0.1 mm × 0.1 μm) column in the second dimension was used to separate 188 out of 209 congeners. A further 12 congeners were identified through additional data processing resulting in the identification of a total of 200 congeners. However, caution is advised if these 12 congeners were to be used in quantitative assessments. The remaining 9 co-eluting congeners were three doublets (CB65 + CB62, CB160 + CB163 and CB201 + CB204) and one triplet (CB20 + CB21 + CB33). This method was tested on five Aroclors and resulted in the separation of all congeners present in the heavier Aroclor mixtures A1254 and A1260. The suitability of this method for applications in biological matrices was demonstrated on extracted whiting and guillemot liver samples which resulted in the identification of 137 individual PCBs in the whiting liver sample and 120 in the guillemot sample. Fingerprinting ...
In the second half of the twentieth century, increasing efforts were made towards containing and ... more In the second half of the twentieth century, increasing efforts were made towards containing and cleaning contaminated groundwater. A number of techniques can be used to achieve such goals, traditionally either by treating or isolating the soil in situ, or by removing it for washing or disposal. However, such technologies tend to be accompanied by high energy consumption, and can lead to new environmental problems. Therefore, more efficient and economical techniques are needed to remediate contaminated soil and groundwater. ...
Reductive dechlorination of trichloroethene (TCE) by zero-valent iron produces a systematic enric... more Reductive dechlorination of trichloroethene (TCE) by zero-valent iron produces a systematic enrichment of 13C in the remaining substrate that can be described using a Rayleigh model. In this study, fractionation factors for TCE dechlorination with iron samples from two permeable reactive barriers (PRBs) were established in batch experiments. Samples included original unused iron as well as material from a barrier
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Papers by Robert Kalin