Ozonation of oil sands process-affected water accelerates microbial bioremediation.

Ozonation can degrade toxic naphthenic acids (NAs) in oil sands process-affected water (OSPW), but even after extensive treatment a residual NA fraction remains. Here we hypothesized that mild ozonation would selectively oxidize the most biopersistent NA fraction, thereby accelerating subsequent NA biodegradation and toxicity removal by indigenous microbes. OSPW was ozonated to achieve approximately 50% and 75% NA degradation, and the major ozonation byproducts included oxidized NAs (i.e., hydroxy- or keto-NAs). However, oxidized NAs are already present in untreated OSPW and were shown to be formed during the microbial biodegradation of NAs. Ozonation alone did not affect OSPW toxicity, based on Microtox; however, there was a significant acceleration of toxicity removal in ozonated OSPW following inoculation with native microbes. Furthermore, all residual NAs biodegraded significantly faster in ozonated OSPW. The opposite trend was found for ozonated commercial NAs, which are known to contain no significant biopersistent fraction. Thus, we suggest that ozonation preferentially degraded the most biopersistent OSPW NA fraction, and that ozonation is complementary to the biodegradation capacity of microbial populations in OSPW. The toxicity of ozonated OSPW to higher organisms needs to be assessed, but there is promise that this technique could be applied to accelerate the bioremediation of large volumes of OSPW in Northern Alberta, Canada.

Effects of an onion by-product on bioactivity and safety markers in healthy rats.

Onions are excellent sources of bioactive compounds including fructo-oligosaccharides (FOS) and polyphenols. An onion by-product was characterised in order to be developed as a potentially bioactive food ingredient. Our main aim was to investigate whether the potential health and safety effects of this onion by-product were shared by either of two derived fractions, an extract containing the onion FOS and polyphenols and a residue fraction containing mainly cell wall materials. We report here on the effects of feeding these products on markers of potential toxicity, protective enzymes and gut environment in healthy rats. Rats were fed during 4 weeks with a diet containing the products or a control feed balanced in carbohydrate. The onion by-product and the extract caused anaemia as expected in rodents for Allium products. No other toxicity was observed, including genotoxicity. Glutathione reductase (GR) and glutathione peroxidase (GPx1) activities in erythrocytes increased when rats were fed with the onion extract. Hepatic gene expression of Gr, Gpx1, catalase, 5-aminolevulinate synthase and NAD(P)H:quinone oxidoreductase was not altered in any group of the onion fed rats. By contrast, gamma-glutamate cysteine ligase catalytic subunit gene expression was upregulated but only in rats given the onion residue. The onion by-products as well as the soluble and insoluble fractions had prebiotic effects as evidenced by decreased pH, increased butyrate production and altered gut microbiota enzyme activities. In conclusion, the onion by-products have no in vivo genotoxicity, may support in vivo antioxidative defence and alter the functionality of the rat gut microbiota.

Determination of heterocyclic aromatic amines in human urine by using hollow-fibre supported liquid membrane extraction and liquid chromatography-ultraviolet detection system.

A hollow-fibre supported liquid membrane (HF-SLM) extraction method has been developed for determination of 11 heterocyclic aromatic amines (HCAs) in human urine samples by using high performance liquid chromatography (HPLC) equipped with an ultraviolet (UV) absorbance detector. These compounds were extracted from an alkaline urine sample (donor phase) into the organic solvent residing in the pores of a polypropylene hollow fibre and then back extracted into an acidic solution (acceptor phase) inside the lumen of the hollow fibre. After extraction, HCAs were analyzed by injecting the analyte enriched acceptor phase into the HPLC. The analyte enrichment factors ranged between 241 and 339 obtained in a 90 min extraction time, and method detection limits (MDL) ranged between 0.1 and 0.5 microg L(-1) with relative standard deviation (RSD) values between 3.4% and 11%. The extraction technique employed in this work is easy to use and rapid as it involves only a few minutes manipulation of each sample. It is the most economical sample preparation/preconcentration technique to our knowledge as compared to other microextraction techniques.

Advances and developments in membrane extraction for gas chromatography: Techniques and applications.

This review article focuses on advances and technical developments of the realm of membrane extraction techniques for the analytes that are (made) amenable to gas chromatographic analysis, and sheds light on the analytical applications to biological and environmental samples. In this review, the state of the art in this growing area of membrane extraction for gas chromatography is presented and several selected examples from our work and that of other groups are discussed. The published articles on the techniques and their applications, found in the scientific literature between the years 2000 and May 2007 and cited in over than 100 references, are perused and commented. A good deal of light will be thrown on the novelty of the techniques, instrumentations and applications. The mentioned techniques are mainly microporous membrane liquid-liquid extraction, extracting syringe, two-phase hollow-fibre-protected liquid-phase microextraction and its modifications, and membrane extraction with sorbent interface and its variants. The merits and demerits of the techniques will be highlighted.

A simplified hollow-fibre supported liquid membrane extraction method for quantification of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) in urine and plasma samples.

A simple and easy-to-use extraction procedure has been optimised, validated, and applied for extraction of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) in urine and spiked plasma samples. PhIP is a carcinogenic and mutagenic heterocyclic aromatic amine that is formed during cooking of meat and fish. The novelty of the extraction procedure lies in using a short piece of narrow capillary-like microporous hollow-fibre (HF) membrane as extraction device. The HF membrane was filled with a few microlitres of acidic solution and the membrane pores were impregnated with an organic extraction solvent. Therefore, the technique was called hollow-fibre supported liquid membrane (HF-SLM) extraction. The HF extraction device was then supported by a syringe needle and directly immersed in urine (1.4 mL) or plasma (0.3 mL) previously made alkaline by adding 0.5 mol L(-1) NaOH solution to give a final volume of 1.6 mL. The operation of the HF-SLM extraction at the optimal conditions resulted in a PhIP extraction efficiency of 74% from both spiked urine and plasma, corresponding to enrichment factors of 126 and 27, respectively. For 90 min extraction time, limits of detection and quantification were, respectively, 8 and 25 pg mL(-1) for urine and 6 and 11 pg mL(-1) for plasma. Within-day repeatability (n = 6) and between-day reproducibility (n = 3) were, respectively, 5% and 13% for urine and 6% and 7% for plasma. Analysis of urine samples collected for 12 h after a volunteer had eaten 250 g well-done chicken showed the PhIP concentration was 124 +/- 21 pg mL(-1), calculated assuming an extraction efficiency of 74%.

A novel hollow-fibre microporous membrane liquid-liquid extraction for determination of free 4-isobutylacetophenone concentration at ultra trace level in environmental aqueous samples.

In this study, a method was developed for determination of the free concentration of 4-isobutylacetophenone, a toxic degradation product of ibuprofen, in river and sewage water samples from Sweden. Sample preparation and analysis were performed by a hollow-fibre microporous membrane liquid-liquid extraction (HF-MMLLE) set-up and gas chromatography-mass spectrometry (GC-MS), respectively. In this novel approach, only the liquid in the membrane pores is utilised for non-depleting extraction. Several parameters were studied, including: type of organic solvent, sample pH, and salt and humic acid content. The optimised method allowed the determination of the analyte at the ng L(-1) level in river and sewage water. A linear plot gave a correlation coefficient better than 0.992 and resulted in a limit of detection of 7 and 14 ng L(-1) for river and sewage water, respectively. The enrichment factor was over 2000 in the fibre and over 300 after dilution. The repeatability and reproducibility were better than 5% and 10%, respectively. For the first time, 4-isobutylacetophenone was found at free concentrations of 40 ng L(-1) or below in sewage waters, while it could not be quantified in a river downstream from a municipal sewage treatment plant.

Determination of polybrominated diphenyl ethers at trace levels in environmental waters using hollow-fiber microporous membrane liquid-liquid extraction and gas chromatography-mass spectrometry.

In this study, we present a simple and easy-to-use extraction method that is based on a hollow-fiber microporous membrane liquid-liquid extraction (HF-MMLLE), as an extraction technique, followed by gas chromatography-mass spectrometry (GC-MS) to determine a group of brominated flame retardants (BFRs), polybrominated diphenyl ethers (PBDEs), at trace levels in aqueous samples. The hollow-fiber membrane (HF) filled with organic solvent was immersed into the aqueous sample, spiked with the analytes at ng l(-1) level, and stirred for 60 min. The proposed method could attain enrichment factors (E(e)) up to 5200 times, after optimising parameters, such as organic solvent, stirring speed and extraction time, that affect the extraction. The HF-MMLLE-GC-MS method was successfully applied to the extraction of PBDEs from tap, river and leachate water samples with spike recoveries ranging from 85% to 110%. The method validation with reagent and leachate water samples provided good linearity, detection limits of 1.1 ng l(-1) or lower, both in reagent and leachate water, as well as satisfactory precision in terms of repeatability and reproducibility with values of % relative standard deviation (%RSD) lower than 8.6 and 16.9, respectively.

Extracting Syringe for determination of organochlorine pesticides in leachate water and soil-water slurry: a novel technology for environmental analysis.

The Extracting Syringe (ESy), a novel membrane-based sample preparation technique directly coupled as an autosampler to gas chromatography, has been employed for the analysis of organochlorine pesticides (OCPs) in raw leachate water. The ESy has also been applied for extraction of OCPs from contaminated soil samples and its performance has been compared to liquid-solid extraction (LSE) and accelerated solvent extraction (ASE). Extraction of 3-mL leachate sample at the optimised conditions resulted in enrichment factors from 32 (Endrin aldehyde) to 242 (Endrin) and detection limits from 1 to 20 ng/L. The inter-day and intra-day repeatability (% RSD) at 100 and 500 ng/L were <6% and <24%, respectively. The relative recovery at 100 and 500 ng/L ranged from 68% (Aldrin) to 116% (Endrin aldehyde); except Heptachlor that showed 51 and 60%, respectively. The ESy extraction of the slurry-made soil samples revealed occurrence of Endosulfan I (18.2 microg/g soil), 4,4'-DDE (2.6 ng/g soil), Endosulfan II (8.7 microg/g soil) and Endosulfan sulfate (1.1 microg/g soil); showing good agreement with LSE results. The total ESy consumption of organic solvents was 4.2 mL from which only 0.6 mL n-undecane was used during the extraction step (7 microL for the extraction per se), while in the LSE and ASE, it was 420 and 18.1 mL, respectively. The ESy extraction time (0.5 h) was comparable to the ASE time (0.6 h); and the time required for the LSE was 3.75 h. To sum up, the ESy has shown its competency to LSE and ASE technologies, demonstrating its applicability for environmental analysis of organic pollutants, towards green techniques for green environment.

Miniaturized and automated sample pretreatment for determination of PCBs in environmental aqueous samples using an on-line microporous membrane liquid-liquid extraction-gas chromatography system.

A new, fast, and automated sample pretreatment technique for determination of lipophilic organic compounds in aqueous samples has been developed and applied to the determination of polychlorinated biphenyls (PCBs) in environmental river water. It is based on miniaturized microporous membrane liquid-liquid extraction coupled on-line to gas chromatography (GC) with electron capture detection. The heart of the system that simultaneously connects the sample pretreatment step to the final GC analysis has been named the extracting syringe (ESy). The ESy carries a miniaturized membrane extraction card attached to an electrically and mechanically designed installment and is mounted directly over a GC injector for fully automated injection of the extract. A method was developed to extract 10 PCB congeners from 1-mL water samples (after addition of 40% acetonitrile) with an extraction time of 10 min. The optimized methodology showed good linearity (in the dynamic concentration range of 5 ng L(-)(1)-1 microg L(-)(1)), enrichment factors of 33-40 times, repeatable extractions (RSD 2-5%, n = 4), and low detection limits (2-3 ng L(-)(1)). Acetonitrile had to be added to the samples in order to overcome the influence of PCB adsorption on the repeatability of extraction and enrichment and to minimize the overall memory effect (OME). OME and carryover depended not only on the concentration of the organic solvent added to the sample and that used in the washing procedure but also on whether the extracting card was changed or not. When an optimized washing procedure was applied, the OME was approximately 0.2% at high concentrations (i.e., 1 microg L(-)(1)). When each extraction took place in a new extraction card, no OME was detected. Additionally, no significant adsorption onto glass surfaces or a matrix effect on extraction was noticed. The main features of this methodology are good extraction repeatability, low detection limits at short extraction time, and the unsurpassed characteristic of no detectable OME in the entire system when each sample is processed in a new card. The total consumption of organic (nonchlorinated) solvents is less than 5 mL per sample.