Methodologies for Analysis and Identification of Total Petroleum Hydrocarbons

Development, optimization, validation and application of faster gas chromatography – flame ionization detector method for the analysis of total petroleum hydrocarbons in contaminated soils

The paper describes a method to quantify hydrocarbons in air exclusively on the basis of chromatographic parameters without the need for calibration. A simple technique is presented to estimate distribution coefficients (K) between air and the poly(dimethylsiloxane) solid phase microextraction (SPME) fiber coating using the linear temperature-programmed retention index system (LTPRI). There is a linear relationship (r(2) = 0.99989) between the log K for a series of n-alkanes and LTPRI, thus providing a means by which establishing a K for any peak in a chromatogram is possible given its published or experimentally determined LTPRI. This alternative approach to establishing K values significantly enhances and simplifies the use of SPME for sampling and analyzing air for quantification of compounds without the need for fiber calibration. Analysis of a group of 29 isoparaffinic compounds and a group of 33 aromatic compounds showed excellent agreement between their theoretical air to fiber distribution coefficients based on LTPRI and the experimentally obtained distribution coefficients. In addition, for a very complex mixture of organics such as gasoline, SPME can establish a total petroleum hydrocarbon in air level using LTPRI. This method was carefully evaluated, and the results were essentially identical between standard procedures and the proposed simple procedure described in the paper.

Analysis of total petroleum hydrocarbons, polycyclic aromatic hydrocarbons and risk assessment of heavy metals in some selected finfishes at Forcados Terminal, Delta State, Nigeria

The aquatic microbial communities are relatively complex with a high level of prokaryotic diversities. Standard and novel microbiological, analytical, and statistical techniques were employed in the collection, analysis, and comprehensive study of the samples. From the study, the mean values of total heterotrophic bacteria were determined to be 1.35 ± 0.18 (×107), 1.59 ± 0.64 (×107), and 1.56 ± 0.52 (×107) for upstream, midstream, and downstream, respectively, while the mean values for crude oil-utilizing bacteria were 1.08 ± 0.12 (×106), 1.28 ± 0.58 (×106), and 1.24 ± 0.44 (×106) for upstream, midstream, and downstream, respectively. The mean concentrations of physicochemical parameters and heavy metals obtained in the benthic sediment were significantly higher than the mean concentrations in the water samples (tidal and intertidal) (p < 0.02). The result of the component analysis of total petroleum hydrocarbons (including polycyclic aromatic hydrocarbon and benzene, toluene, ethylbenzene, and xylene) revealed significantly higher levels in the sediment than tidal and intertidal water. Structural metagenomics revealed seven top phyla, namely, Proteobacteria, Actinobacteria, Firmicutes, Bacteroidetes, Planctomycetes, Fusobacteria, and Chloroflexi. The significantly (p < 0.05) high levels of hydrocarbon-utilizing microorganisms in Iko River estuary can be taken as a sensitive index of environmental exposure to hydrocarbon pollutants in the estuary. This research revealed the response patterns of microorganisms to natural and anthropogenic gradients toward sustainability in Iko River estuary.

This paper summarizes the results of a 5-y research study of the nature and toxicity of petroleum biodegradation metabolites in groundwater at fuel release sites that are quantified as diesel-range "Total Petroleum Hydrocarbons" (TPH; also known as TPHd, diesel-range organics (DRO), etc.), unless a silica gel cleanup (SGC) step is used on the sample extract prior to the TPH analysis. This issue is important for site risk management in regulatory jurisdictions that use TPH as a metric; the presence of these metabolites may preclude site closure even if all other factors can be considered "low-risk." Previous work has shown that up to 100% of the extractable organics in groundwater at petroleum release sites can be biodegradation metabolites. The metabolites can be separated from the hydrocarbons by incorporating an SGC step; however, regulatory agency acceptance of SGC has been inconsistent because of questions about the nature and toxicity of the metabolites. The present study was conducted to answer these specific questions. Groundwater samples collected from source and downgradient wells at fuel release sites were extracted and subjected to targeted gas chromatography-mass spectrometry (GC-MS) and nontargeted two-dimensional gas chromatography with time-of-flight mass spectrometry (GC×GC-MS) analyses, and the metabolites identified in each sample were classified according to molecular structural classes and assigned an oral reference dose (RfD)-based toxicity ranking. Our work demonstrates that the metabolites identified in groundwater at biodegrading fuel release sites are in classes ranked as low toxicity to humans and are not expected to pose significant risk to human health. The identified metabolites naturally attenuate in a predictable manner, with an overall trend to an increasingly higher proportion of organic acids and esters, and a lower human toxicity profile, and a life cycle that is consistent with the low-risk natural attenuation paradigm adopted by many regulatory agencies for petroleum release sites. Integr Environ Assess Manag 2017;13:714-727. © 2016 The Authors. Integrated Environmental Assessment and Management Published by Wiley Periodicals, Inc. on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Supercritical fluid extraction with carbon dioxide for the determination of total petroleum hydrocarbons in soil

Analysis of the total petroleum hydrocarbons (TPH) and the activities of hydrocarbon-utilizing bacteria (HUB) and diazotrophic bacteria (DB) in mangrove sediments of the Qua Iboe Estuary revealed that the organic-laden sediments have high hydrocarbon repository status. The epipelic sediment was relatively richer in total organic nitrogen (TON) content. Correlation analysis revealed positive relationship between TPH and HUB (r = 0.60) in the epipelic sediment, while no definite relationship (r = − 0.30) was established between the variables in benthic sediment. A strong negative relationship was observed between TPH and TON in the intertidal (r = − 0.746) and benthic (r = − 0.838) sediments. However, weak positive (r = 0.451) relations were established between TPH and log-transformed densities of DB in both the epipelic and benthic sediment. These indicate that although hydrocarbons contamination may have a direct negative effect on nitrogen availability in mangrove sediment, it has variable influence on the activities of nitrogen fixers. The effect on nitrogenase activity was much stronger in the “oxic” epipelic than the “hypoxic” benthic sediments. Of the 21 bacterial species isolated, only 7 – Azotobacter, Bacillus subtilis, Bacillus sp, Chromatium sp, Klebsiella sp, Moraxella sp, and Pseudomonas aeruginosa – have been implicated in nitrogen fixation. Chromatium sp, a microaerophilic nitrogen-fixing bacterium failed to utilize hydrocarbons while Bacillus megaterium, Micrococcus sp, Acetobacterium sp, Flavobacterium, Nocardia, and Alcaligenes species with no nitrogenase activity demonstrated oil-degrading capabilities. Among the free-living, facultative anaerobic nitrogen fixers encountered Bacillus subtilis, Bacillus sp, and Pseudomonas aeruginosa were prevalent, less affected, and exhibited strong ability to degrade hydrocarbons. These species of free-living nitrogen fixers are recommended for the remediation of oil-contaminated ecosystems in the Niger Delta of Nigeria.

A high-efficient method for determining the total petroleum hydrocarbon (TPH) was established by gas chromatography-flame ionization detection, coupled with an efficient 10m short chromatographic column; the analyzing period was narrowed to 5mins. The limits of detection of the methodincluded 1.47, 4.02, and 0.69mg/kg, and the corresponding limits of quantification reached 4.45, 12.2, and 2.10mg/kg for the three fractions C10-C16, C17-C34, and C35-C40, respectively. The method was employed to real samples to achieve the routine environmental monitoring of TPH in polluted sites from Fushan oilfield, China. As revealed from the analysis of 30 soil samples in the study area, a wide range of TPH concentrations were achieved: 61.6-7300mg/kg (average, 1055mg/kg) for ΣC10-C16, 438-14,280mg/kg (average, 4544mg/kg) for ΣC17-C34, 25.4-638mg/kg (average, 250mg/kg) for ΣC35-C40, and 617-15,348 (average, 5848mg/kg) for ΣC10-C40, respectively. According to the Nemerow integrated pollution index, the Fushan oilfield has been slightly polluted by TPH. As suggested from the distribution of TPH concentrations, the main sources of TPH in soil samples of Fushan oilfield included oil spills during temporary storage, transportation, and oil exploitation. Adopting the developed method to delve into oilfield soil samples further verifies the effectiveness of the method, indicating that the method can well meet the growing demand of regulatory guidelines for related risk assessment and environmental monitoring and remediation strategy formulation.

A comparative study of supercritical fluid extraction and accelerated solvent extraction of lipophilic compounds from lignocellulosic biomass

Comparison of supercritical CO2 extraction and pressurized fluid extraction for isolation of alkaloids from Anacardium occidentale with the study of its anti-inflammatory activity

Extraction of hexaconazole residues which had been weathered over periods of time varying between 0 and 52 weeks was undertaken from two characterized soils. The various extraction techniques considered were Soxhlet extraction, microwave-assisted extraction, supercritical fluid extraction and accelerated solvent extraction. The results indicated that the physico-chemical properties of the soil are an important factor in the extraction of weathered residues of hexaconazole from soil. Overall the results obtained by accelerated solvent extraction were comparable to those obtained by Soxhlet extraction. Some matrix dependence of supercritical fluid extraction and microwave-assisted extraction was noted for the aged (52 week) sampled sandy loam soil. This effect was not evident for any of the extraction techniques using the sandy clay soil. The best precision was obtained for the automated accelerated solvent extraction system.

The impact of crude oil contamination on the environment, especially on soil quality, has been a major concern in Nigeria and for regulatory bodies worldwide. This study focused on assessing the phytoremediation potential of two plant species T. spathecea and P.balfouriana, grown on crude oil-contaminated soils. The plant were cultivated in soils polluted with crude oil at concentrations of 0, 50, 100, 150 and 200 mL/kg. The research was laid out in a 5 x 5 factorial experiment with three replicates, in a completely randomized designed to give a total of 75 experimental units. The gas chromatographic flame ionization detector (GC-FID) was used in determining the total petroleum hydrocarbon (TPH), the atomic absorption spectrophotometer (AAS) was used to determine the heavy metals. The relevant analytical techniques of APHA and AOAC (2020) was used to determine the phytochemical contents of the plant species. The results of TPH analysis revealed that the concentration of TPH increased with the rising concentration of crude oil pollutant in the soil. TPH values were 1,120 mg/kg for P. balfouriana and 2,762.79 mg/kg for T. spathecea. Both plant species showed considerable growth despite increasing crude oil concentrations. The results of heavy metals phytoextraction indicated a trend of increasing metal concentrations with increasing crude oil pollution. Copper concentration ranged from 2.28 mg/kg in T. spathecea to 12.64 mg/kg in R. simplex. Iron uptake ranged from 11.36 mg/kg in P. balfouriana to 22.40 mg/kg T. spathcea. The uptake of manganese increased from 5.56 mg/kg in P. balfouriana to 10.56 gm/kg in T. spathecea, while cobalt concentration decreased from 0.08 mg/kg in T. spathecea to 0.04 mg/kg in P. balfouriana. The study highlights the potential of P. balfouriana and T. spathecea for phytoremediation in crude-contaminated soils and advocates for their use as effective tools for soil remediation.

Bioremediation is a low-cost approach for crude oil spill remediation, but it is often limited by electron acceptor availability. In addition, the biodegradation products of crude oil contaminants are complex, and transformation pathways are difficult to decipher. This study demonstrates that bioelectrochemical systems (BESs) can be effective in crude oil degradation by integrating biological and electrochemical pathways, and more importantly, it provides the first understanding on the daughter products of bioelectrochemical hydrocarbon degradation. Using electrospray ionization (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and two-dimensional gas chromatography (GC × GC), the results showed that the active BES reactor improved the total petroleum hydrocarbon (TPH) degradation by ∼70% than open circuit control reactors. After separating the daughter products into nine fractions (MA1-MA9) according to the molecular weight (m/z 200-1000) by modified aminopropyl silica (MAPS) fractionation, we found that active BES remediation resulted in 50% more polar, oxygen-containing naphthenic (NAP) acids. The MA4 fraction (centered at ∼550 Da) increased by 47%, and MA5 and MA7 fractions with higher molucular weight increased by a maximum of ∼7- and 9-fold, respectively. These results are in accordance with the variation of bulk elemental compositions in O2 species, where daughter transformation products doubled relative to parent oil extract. The contribution of newly generated NAP acids was mainly from higher-order oxygen species (O5-O6) with increased hydrophobicity in conjunction with a decreased abundance in lower-order oxygen species (O1). Overall, the study suggests that n-alkane degradation occurred via β-oxidation to oxygenated transformation products with lower molecular weight, such as n-alcohols in O1 class and subsequently to n-fatty acids in O2 class.

The root of Salix aegyptiaca L. was extracted using their yield percentage, total condensed tannin concentration, antimicrobial, antioxidant activity and to determine chemical composition by LC-MS/MS. The root extraction was carried out together with water, ethanol and methanol. Accelerated solvent extraction (ASE), conventional extraction (CE), and microwave extraction (ME) were the extraction methods applied during the investigation. The LC-MS/MS methanol extract was used to detect phenolics. The antioxidant activities and total condensed tannin concentrations of root extracts have been done by UV-visible spectroscopy from 517 to 580 nm, severally. The disk diffusion method was used for antimicrobial activity. The maximum extraction yield (17.2%) was obtained in methanol by the ASE technique whereas, the conventional extraction technique obtained the minimum extraction efficiency (9.1%). By triplicate measurement, the total condensed tannin analysis result was found 35.14 mg/L. Using the ASE technique, the methanol extract was the maximum inhibitory zone (26 mm) against Candida albicans ATCC 10231. However, in water extract by conventional extraction, a minimum inhibitory zone (11 mm) was obtained against Staphylococcus aureus Cowan 1. The highest and lowest DPPH scavenging activity was determined in methanol (ASE) (98.8%) and ethanol (97.5%) extract respectively. The maximum amounts of quinic acid (63895 µg/g) were discovered using LC-MS/MS.

Population growth, municipal waste management challenges, fossil fuel depletion and its associated pollution are increasingly becoming public health issues. These necessitate the production of renewable and sustainable biofuels. This study, therefore, employed the use of hydrothermal liquefaction for the conversion of sewage sludge to bio-crude oil. Samples of the sewage sludge were purposively collected from sewage treatment plant and subjected to laboratory analyses (in triplicates) using standard methods (ASTM and AOAC) to obtain the composition. Sewage sludge (25 kg) from the sewage treatment Plant of University College Hospital, Ibadan, was converted at 300oC to bio-crude oil and biochar using hydrothermal liquefaction. The bio-crude oil was analysed for its physico-chemical properties. Conversion product yield gave 34% bio-crude oil with cloud point, pour point, viscosity and density of -38.89oC, -36.11oC, 0.86cP and 1.04gml-1respectively. The Higher Heating Value (HHV) of the bio-crude oil was 30.60 MJ/kg. A total of 18 compounds were identified from the analysis of Total Petroleum Hydrocarbon (TPH) in the bio-crude oil with 17 compounds within the diesel range organics of crude oil which showed that bio-crude oil has great potential to serve as alternative to fossil fuels.