Piri-Moghadam H.,University of Waterloo |
Gionfriddo E.,University of Waterloo |
Rodriguez-Lafuente A.,Maxxam Analytics |
Grandy J.J.,University of Waterloo |
And 3 more authors.
Analytica Chimica Acta | Year: 2017
The primary goal of the present study is the inter-laboratory evaluation of a thin film microextraction (TFME) technique to be used as an alternative approach to liquid-liquid extraction (LLE). Polydimethylsiloxane/divinylbenzene (PDMS/DVB) and PDMS/DVB-carbon mesh supported membranes were used for the extraction of 23 targeted pesticides, while a thermal desorption unit (TDU) was employed to transfer these analytes to a GC/MS instrument for separation and detection. After optimization of the most critical parameters, both membranes were capable of achieving limits of detection (LOD) in the low ng L−1 range while demonstrating excellent robustness, withstanding up to 100 extractions/desorption cycles. Furthermore, limits of quantification (LOQ) between 0.025 and 0.50 μg L−1 were achieved for the 23 compounds selected from several classes of pesticides with a wide range of polarities. A wide linear range of 0.025–10.0 μg L−1 with strong correlation to response (R2 > 0.99) was attained for most of the studied analytes. Both membranes showed good accuracy and repeatability at three levels of concentration. Moreover, the method was also validated through blind split analyses of 18 surface water samples, collected within 3 months, using TFME at the University of Waterloo and LLE at Maxxam Analytics (Mississauga, ON) which is an accredited commercial analytical laboratory. Good agreement between the two methods was achieved with accuracy values ranging from 70 to 130%, for the majority of analytes in the samples collected. At the concentration levels investigated, 90% of the analytes were quantifiable by TFME, whereas only 53% of the compounds were reportable using the LLE method particularly at concentrations lower than 1 μg L−1. The comparison of TFME and LLE from several analytical aspects demonstrated that the novel TFME method gave similar accuracy to LLE, while providing additional advantages including higher sensitivity, lower sample volume, thus reduced waste production, and faster analytical throughput. Given the sensitivity, simplicity, low cost, accuracy, greenness and relatively fast procedure of TFME, it shows great potential for adoption in analytical laboratories as an alternative to LLE. © 2017 Elsevier B.V.
Seidman D.,Virginia Commonwealth University |
Ojogun N.,Virginia Commonwealth University |
Walker N.J.,University of California at Davis |
Mastronunzio J.,Yale University |
And 11 more authors.
Cellular Microbiology | Year: 2014
Anaplasma phagocytophilum, which causes granulocytic anaplasmosis in humans and animals, is a tick-transmitted obligate intracellular bacterium that mediates its own uptake into neutrophils and non-phagocytic cells. Invasins of obligate intracellular pathogens are attractive targets for protecting against or curing infection because blocking the internalization step prevents survival of these organisms. The complement of A.phagocytophilum invasins is incompletely defined. Here, we report the significance of a novel A.phagocytophilum invasion protein, AipA. A.phagocytophilum induced aipA expression during transmission feeding of infected ticks on mice. The bacterium upregulated aipA transcription when it transitioned from its non-infectious reticulate cell morphotype to its infectious dense-cored morphotype during infection of HL-60 cells. AipA localized to the bacterial surface and was expressed during in vivo infection. Of the AipA regions predicted to be surface-exposed, only residues 1 to 87 (AipA1-87) were found to be essential for host cell invasion. Recombinant AipA1-87 protein bound to and competitively inhibited A.phagocytophilum infection of mammalian cells. Antiserum specific for AipA1-87, but not other AipA regions, antagonized infection. Additional blocking experiments using peptide-specific antisera narrowed down the AipA invasion domain to residues 9 to 21. An antisera combination targeting AipA1-87 together with two other A.phagocytophilum invasins, OmpA and Asp14, nearly abolished infection of host cells. This study identifies AipA as an A.phagocytophilum surface protein that is critical for infection, demarcates its invasion domain, and establishes a rationale for targeting multiple invasins to protect against granulocytic anaplasmosis. © 2014 John Wiley & Sons Ltd.
Yao Y.,Environment Canada |
Volchek K.,Dillon Consulting Limited |
Brown C.E.,Maxxam Analytics
Proceedings of the 38th AMOP Technical Seminar on Environmental Contamination and Response | Year: 2015
Aqueous film forming foam (AFFF) formulations contain fluorinated surfactants that are used to extinguish hydrocarbon-fueled fires. Past and ongoing firefighting training activities have led to groundwater and soil contamination by perfluorinated compounds (PFCs) due to uncontrolled release of AFFFs. Very few studies have reported the occurrence and environmental levels of PFCs and other co-occurring pollutants at AFFF-impacted areas around the world. In this study, we characterized groundwater and soil samples collected from a current Canadian firefighting training site for a wide range of PFCs and co-contaminants including PHCs, VOCs, PCBs, PAHs, and metals. The results revealed the full profiles of these contaminants in both groundwater and soil at the site. More than ten PFCs were detected from the groundwater and soil samples, among which perfluorooctane sulfonate (PFOS) exceeded the Federal Contaminated Sites Action Plan (FCSAP) criteria in both groundwater and soil samples. The measured PFOS concentrations in groundwater (1,200 μg L-1) and top soil layer (35 mg kg-1) are 20 and 7 times higher than the FCSAP criteria for groundwater (60 μg L-1) (for the protection of aquatic life) and soil (5 mg kg-1) (for industrial land use - commercial without toddler), respectively. The information is of importance not only for environmental site assessment but also for the selection, design and optimization of PFC treatment technology, in case site remediation is required.
Yao Y.,Environment Canada |
Volchek K.,Environment Canada |
Brown C.E.,Environment Canada |
Robinson A.,Maxxam Analytics |
Obal T.,Maxxam Analytics
Water Science and Technology | Year: 2014
Perfluorinated compounds (PFCs) are emerging environmental pollutants. Perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) are the two primary PFC contaminants that are widely found in water, particularly in groundwater. This study compared the adsorption behaviors of PFOS and PFOA on several commercially available adsorbents in water. The tested adsorbents include granular activated carbon (GAC: Filtrasorb 400), powdered activated carbon, multi-walled carbon nanotube (MCN), double-walled carbon nanotube, anion-exchange resin (AER: IRA67), non-ion-exchange polymer, alumina, and silica. The study demonstrated that adsorption is an effective technique for the removal of PFOS/PFOA from aqueous solutions. The kinetic tests showed that the adsorption onto AER reaches equilibrium rapidly (2 h), while it takes approximately 4 and 24 h to reach equilibrium for MCN and GAC, respectively. In terms of adsorption capacity, AER and GAC were identified as the most effective adsorbents to remove PFOS/PFOA from water. Furthermore, MCN, AER, and GAC proved to have high PFOS/PFOA removal efficiencies (≥98%). AER (IRA67) and GAC (Filtrasorb 400) were thus identified as the most promising adsorbents for treating PFOS/PFOA-contaminated groundwater at mg L-1 level based on their equilibrium times, adsorption capacities, removal efficiencies, and associated costs. © Her Majesty the Queen in Right of Canada 2014
Goulet R.R.,Canadian Nuclear Safety Commission |
Thompson P.A.,Canadian Nuclear Safety Commission |
Serben K.C.,Golder Associates |
Eickhoff C.V.,Maxxam Analytics
Environmental Toxicology and Chemistry | Year: 2015
Treated effluent discharge from uranium (U) mines and mills elevates the concentrations of U, calcium (Ca), magnesium (Mg), and sulfate (SO4 2-) above natural levels in receiving waters. Many investigations on the effect of hardness on U toxicity have been experiments on the combined effects of changes in hardness, pH, and alkalinity, which do not represent water chemistry downstream of U mines and mills. Therefore, more toxicity studies with water chemistry encountered downstream of U mines and mills are necessary to support predictive assessments of impacts of U discharge to the environment. Acute and chronic U toxicity laboratory bioassays were realized with 6 freshwater species in waters of low alkalinity, circumneutral pH, and a range of chemical hardness as found in field samples collected downstream of U mines and mills. In laboratory-tested waters, speciation calculations suggested that free uranyl ion concentrations remained constant despite increasing chemical hardness. When hardness increased while pH remained circumneutral and alkalinity low, U toxicity decreased only to Hyalella azteca and Pseudokirchneriella subcapitata. Also, Ca and Mg did not compete with U for the same uptake sites. The present study confirms that the majority of studies concluding that hardness affected U toxicity were in fact studies in which alkalinity and pH were the stronger influence. The results thus confirm that studies predicting impacts of U downstream of mines and mills should not consider chemical hardness. Environ Toxicol Chem 2015;34:562-574. © 2014 The Authors. Published by Wiley Periodicals, Inc. © 2014 The Authors. Published by Wiley Periodicals, Inc. on behalf of SETAC.
Souza-Silva T.A.,University of Waterloo |
Jiang R.,Sun Yat Sen University |
Rodriguez-Lafuente A.,Maxxam Analytics |
Gionfriddo E.,University of Waterloo |
Pawliszyn J.,University of Waterloo
TrAC - Trends in Analytical Chemistry | Year: 2015
The present review, the first of a series of three, aims to describe recent developments in solid-phase microextraction (SPME) technology in the fields of environmental analysis applied to complex environmental matrices. We offer the reader an introductory, concise discussion of SPME fundamentals followed by a perspective on the most commonly used sample-preparation methods. We give particular attention to a comparison of the more recent SPME developments. We especially emphasize the development of new devices, such as cold fiber and thin films. We address quantitation in complex environmental matrices in this review with a concise discussion on calibration strategies for SPME methods. © 2015 Elsevier B.V.
Yang Y.,University of Waterloo |
Yang Y.,CAS Lanzhou Institute of Chemical Physics |
Lord H.,University of Waterloo |
Lord H.,Maxxam Analytics |
Pawliszyn J.,University of Waterloo
Journal of Chromatography A | Year: 2013
During in-tube solid phase microextraction, sample mixing with mobile phase contained in the autosampler tubing during extraction may result in some amount of sample becoming entrained in the mobile phase rather than returning to the sample vial or being directed to waste after extraction. In cases where target analytes have relatively low affinity for the sorbent on the wall of the capillary, mixing can impact data quality. Where the sample contains components that may interfere with either the separation (e.g. proteins) or detection (e.g. ions with MS detection), additional difficulties can arise. In the current research, the magnitude of the sample mixing effect was illustrated by analyzing ranitidine and a series of polycyclic aromatic hydrocarbons (PAH). The sample volume equivalent of mixing was calculated as 37. μL for ranitidine and 20. μL for PAHs using the same inner diameter of capillary. To address this issue, a novel approach involving adding a switching valve located between the metering pump and the capillary was developed. Capillary flush conditions, draw/eject speed and extraction time were optimized for ranitidine with the result that in the final method, no mixing of sample with mobile phase was apparent in the detected amounts. To provide information on a compound class with intermediate polarity, two β-blockers were also extracted using the optimized washing conditions respectively. The results indicated that the issue of sample mixing had been resolved for these as well. Finally, in-tube SPME calibration of these three analyte classes was shown to be highly linear, providing further indication that sample mixing was not impacting data quality. Available literature on the subject was surveyed, and a discussion on the rational selection of conditions to guide method development was also provided. © 2013 Elsevier B.V.
Lam G.,Maxxam Analytics |
Zhao S.,Maxxam Analytics |
Sandhu J.,Maxxam Analytics |
Yi R.,Maxxam Analytics |
And 2 more authors.
Drug Testing and Analysis | Year: 2014
Myo-Inositol tris pyrophosphate (ITPP) is a powerful allosteric modulator of haemoglobin that increases oxygen-releasing capacity of red blood cells. It is capable of crossing the red blood cell membrane unlike its open polyphosphate analog myo-inositol hexakisphosphate (IHP). Systemic administration of ITPP enhanced the exercise capacity in mice. There have been rumours of its abuse in the horse racing industry to enhance the performance of racing horses. In this paper, the detection of ITPP in equine plasma and urine after an administration of ITPP is reported. A Standardbred mare was administered 200 mg of ITPP intravenously. Urine and plasma samples were collected up to 120 h post administration and analyzed for ITPP by liquid chromatography-tandem mass spectrometry. ITPP was detected in post administration plasma samples up to 6 hours. The peak concentration was detected at 5 min post administration. In urine, ITPP was detected up to 24 h post administration. The peak concentration was detected at 1.5 h post administration. © Her Majesty the Queen in Right of Canada 2013.
Wu L.,University of Alberta |
Sawada J.A.,University of Alberta |
Kuznicki D.B.,Maxxam Analytics |
Kuznicki T.,University of Alberta |
Kuznicki S.M.,University of Alberta
Journal of Radioanalytical and Nuclear Chemistry | Year: 2014
I-129 is a hazardous fission product due to its long half life and ability to bioaccumulate. Silver mordenite has been studied for the removal of I-129 because of its hydrothermal stability arising from a high Si/Al ratio which subsequently limits its silver loading and iodine capacity. Titanosilicate ETS-10 and the sodium nanotitanate ETS-2 were exchanged to over 35 wt % silver and exposed to saturated iodine vapour at 80 °C under dry and humid conditions. The results indicate that the silver on these materials is reactive toward iodine and that the majority of the silver ions are utilized. © 2014, Akadémiai Kiadó, Budapest, Hungary.