Non-Targeted Analysis of Petroleum Metabolites in Groundwater Using GC×GC–TOFMS

Mohler, Rachel E.; O’Reilly, Kirk T.; Zemo, Dawn A.; Tiwary, Asheesh K.; Magaw, Renae; Synowiec, Karen A.

doi:10.1021/es401706m

Cited by 45 publications

(48 citation statements)

References 24 publications

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“…The results of the present study indicate the value of conducting nontargeted analysis as part of some environmental investigations . Although traditional targeted analysis allows for tracking and quantification of specific compounds, it may tell only a partial story.…”

Section: Resultsmentioning

confidence: 66%

Identification of ester metabolites from petroleum hydrocarbon biodegradation in groundwater using GC×GC‐TOFMS

O’Reilly

Mohler

Zemo

et al. 2015

Enviro Toxic and Chemistry

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Abstract:In an effort to understand the nature and toxicity of petroleum hydrocarbon degradation metabolites, 2-dimensional gas chromatography linked to a time-of-flight mass spectrometer (GCÂGC-TOFMS) was used to conduct nontargeted analysis of the extracts of 61 groundwater samples collected from 10 fuel release sites. An unexpected result was the tentative identification of 197 unique esters. Although esters are known to be part of specific hydrocarbon degradative pathways, they are not commonly considered or evaluated in field studies of petroleum biodegradation. In addition to describing the compounds identified, the present study discusses the role for nontargeted analysis in environmental studies. Overall, the low toxicological profile of the identified esters, along with the limited potential for exposure, renders them unlikely to pose any significant health risk.

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Section: Resultsmentioning

confidence: 66%

Identification of ester metabolites from petroleum hydrocarbon biodegradation in groundwater using GC×GC‐TOFMS

O’Reilly

Mohler

Zemo

et al. 2015

Enviro Toxic and Chemistry

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“…The GC × GC also detected several of the 57 target polar metabolites that were not detected by the traditional GC at detection limits of 10 µg/L, further suggesting that the target polars identified by the GC × GC were present at single digit µg/L levels. A complete list of unique TICs from this study and additional details about the GC × GC‐MS analysis are presented in Mohler et al (in press). DOI: 10.1021/es401706m.…”

Section: Resultsmentioning

confidence: 99%

Nature and Estimated Human Toxicity of Polar Metabolite Mixtures in Groundwater Quantified as TPHd/DRO at Biodegrading Fuel Release Sites

Zemo¹,

O’Reilly²,

Mohler³

et al. 2013

Groundwater Monitoring Rem

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Polar metabolites resulting from petroleum biodegradation are measured in groundwater samples as TPHd unless a silica gel cleanup (SGC) is used on the sample extract to isolate hydrocarbons. Even though the metabolites can be the vast majority of the dissolved organics present in groundwater, SGC has been inconsistently applied because of regulatory concern about the nature and toxicity of the metabolites. A two‐step approach was used to identify polar compounds that were measured as TPHd in groundwater extracts at five sites with biodegrading fuel sources. First, gas chromatography with mass spectrometry (GC‐MS) was used to identify and quantify 57 individual target polar metabolites. Only one of these compounds—dodecanoic acid, which has low potential human toxicity—was detected. Second, nontargeted analysis was used to identify as many polar metabolites as possible using both GC‐MS and GC×GC‐MS. The nontargeted analysis revealed that the mixture of polar metabolites identified in groundwater source areas at these five sites is composed of approximately equal average percentages of organic acids, alcohols and ketones, with few phenols and aldehydes. The mixture identified in downgradient areas at these five sites is dominated by acids, with fewer alcohols, far fewer ketones, and very few aldehydes and phenols. A ranking system consistent with systems used by USEPA and the United Nations was developed for evaluating the potential chronic oral toxicity to humans of the different classes of identified polar metabolites. The vast majority of the identified polar metabolites have a “Low” toxicity profile, and the mixture of identified polar metabolites present in groundwater extracts at these five sites is unlikely to present a significant risk to human health.

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“…They concluded that these were likely biodegradation intermediates of petroleum hydrocarbons (Zemo and Foote ). Zemo et al (, ) argued on the basis of 760 tentatively identified degradation intermediates identified by Mohler et al () that the intermediates pose little to no risk in groundwater, but the issue remains controversial (Mohler et al. ; Brewer and Hellmann‐Blumberg ; ITRC ).…”

Section: Introductionmentioning

confidence: 99%

Examining the Extraction Efficiency of Petroleum‐Derived Dissolved Organic Matter in Contaminated Groundwater Plumes

Zito¹,

Ghannam²,

Bekins³

et al. 2019

Groundwater Monitoring Rem

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The extraction efficiency of petroleum‐derived dissolved organic matter (DOM) was examined for groundwater samples from an aquifer contaminated with crude oil. Five different types of extraction techniques were investigated to determine which method is best suited for the analysis of potentially toxic petroleum‐derived DOM. The five types were a liquid‐liquid extraction (LLE) with dichloromethane (DCM) and total petroleum hydrocarbons‐diesel range (TPHd) with DCM (EPA method 3510C), and three solid‐phase extraction (SPE) stationary phases that are routinely used for extraction of polar analytes from water. For the LLE and TPHd, that is selective for nonpolar compounds, the extraction efficiency of petroleum‐derived DOM decreased downgradient as the petroleum‐derived DOM becomes increasingly polar due to biodegradation. In contrast, the average extraction efficiency by the SPE methods was greater than 65% across the gradient. The results showed that SPE is more efficient for extracting petroleum‐derived DOM at hydrocarbon‐contaminated sites. The use of a method with greater extraction efficiency for partially oxidized hydrocarbons may prove useful in determining relationships between their composition and structure and potential for risks to human health or the environment.

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Non-Targeted Analysis of Petroleum Metabolites in Groundwater Using GC×GC–TOFMS

Cited by 45 publications

References 24 publications

Identification of ester metabolites from petroleum hydrocarbon biodegradation in groundwater using GC×GC‐TOFMS

Identification of ester metabolites from petroleum hydrocarbon biodegradation in groundwater using GC×GC‐TOFMS

Nature and Estimated Human Toxicity of Polar Metabolite Mixtures in Groundwater Quantified as TPHd/DRO at Biodegrading Fuel Release Sites

Examining the Extraction Efficiency of Petroleum‐Derived Dissolved Organic Matter in Contaminated Groundwater Plumes

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