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Correia-Sa L.,Polytechnic Institute of Porto | Fernandes V.C.,Polytechnic Institute of Porto | Fernandes V.C.,Investigation Center | Carvalho M.,Polytechnic Institute of Porto | And 3 more authors.
Journal of Separation Science | Year: 2012

A QuEChERS method has been developed for the determination of 14 organochlorine pesticides in 14 soils from different Portuguese regions with wide range composition. The extracts were analysed by GC-ECD (where GC-ECD is gas chromatography-electron-capture detector) and confirmed by GC-MS/MS (where MS/MS is tandem mass spectrometry). The organic matter content is a key factor in the process efficiency. An optimization was carried out according to soils organic carbon level, divided in two groups: HS (organic carbon >2.3%) and LS (organic carbon <2.3%). Themethod was validated through linearity, recovery, precision and accuracy studies. The quantification was carried out using a matrixmatched calibration to minimize the existence of the matrix effect. Acceptable recoveries were obtained (70-120%) with a relative standard deviation of ≤16% for the three levels of contamination. The ranges of the limits of detection and of the limits of quantification in soils HS were from 3.42 to 23.77 μg kg-1 and from 11.41 to 79.23 μg kg-1, respectively. For LS soils, the limits of detection ranged from 6.11 to 14.78 μg kg-1 and the limits of quantification from 20.37 to 49.27 μg kg-1. In the 14 collected soil samples only one showed a residue of dieldrin (45.36 μg kg-1) above the limit of quantification. This methodology combines the advantages of QuEChERS, GC-ECD detection and GC-MS/MS confirmation producing a very rapid, sensitive and reliable procedure which can be applied in routine analytical laboratories. © 2012 Wiley-VCH Verlag GmbH & Co. KGaA. Source


Correia-Sa L.,Polytechnic Institute of Porto | Correia-Sa L.,University of Porto | Fernandes V.C.,Polytechnic Institute of Porto | Fernandes V.C.,Investigation Center | And 3 more authors.
Food Analytical Methods | Year: 2013

An optimised version of the Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) method for simultaneous determination of 14 organochlorine pesticides in carrots was developed using gas chromatography coupled with electron-capture detector (GC-ECD) and confirmation by gas chromatography tandem mass spectrometry (GC-MS/MS). A citrate-buffered version of QuEChERS was applied for the extraction of the organochlorine pesticides, and for the extract clean-up, primary secondary amine, octadecyl-bonded silica (C18), magnesium sulphate (MgSO4) and graphitized carbon black were used as sorbents. The GC-ECD determination of the target compounds was achieved in less than 20 min. The limits of detection were below the EU maximum residue limits (MRLs) for carrots, 10-50 μg kg-1, while the limit of quantification did exceed 10 μg kg-1 for hexachlorobenzene (HCB). The introduction of a sonication step was shown to improve the recoveries. The overall average recoveries in carrots, at the four tested levels (60, 80, 100 and 140 μg kg-1), ranged from 66 to 111 % with relative standard deviations in the range of 2-15 % (n = 3) for all analytes, with the exception of HCB. The method has been applied to the analysis of 21 carrot samples from different Portuguese regions, and β-HCH was the pesticide most frequently found, with concentrations oscillating between less than the limit of quantification to 14.6 μg kg-1. Only one sample had a pesticide residue (β-HCH) above the MRL, 14.6 μg kg-1. This methodology combines the advantages of both QuEChERS and GC-ECD, producing a very rapid, sensitive and reliable procedure which can be applied in routine analytical laboratories. © 2012 Springer Science+Business Media, LLC. Source


Ibanez-Contreras A.,Investigation Center | Hernandez-Godinez B.,Investigation Center | Hernandez-Godinez B.,Animal Research Unit | Perdigon-Castaneda G.,Imaging Center
Journal of the American Association for Laboratory Animal Science | Year: 2011

In subclavian steal phenomenon (SSP), the subclavian artery develops a stenoocclusive disease proximal to the origin of the vertebral artery, leading to pronounced hemodynamic changes such as arterial flow reversal. Although SSP is a common echographic finding in humans, the phenomenon occurs only rarely in animals; consequently its physiologic features have not been reported previously. Here we describe the clinical and morphologic features of a spontaneous left SSP that was an incidental finding in an 18-y-old female rhesus macaque (Macaca mulatto). Our findings were documented through high-quality imaging studies obtained by using a computerized 3D tomography apparatus and clinical assessment of systolic and diastolic blood pressures. Copyright 2011 by the American Association for Laboratory Animal Science. Source


Rodriguez J.O.,University Militar Nueva Granada | Prieto S.E.,Investigation Center | Correa C.,Investigation Center | Bernal P.A.,National University of Colombia | And 4 more authors.
BMC Medical Physics | Year: 2010

Background: Fractal geometry is employ to characterize the irregular objects and had been used in experimental and clinic applications. Starting from a previous work, here we made a theoretical research based on a geometric generalization of the experimental results, to develop a theoretical generalization of the stenotic and restenotic process, based on fractal geometry and Intrinsic Mathematical Harmony.Methods: Starting from all the possibilities of space occupation in box-counting space, all arterial prototypes differentiating normality and disease were obtained with a computational simulation. Measures from 2 normal and 3 re-stenosed arteries were used as spatial limits of the generalization.Results: A new methodology in animal experimentation was developed, based on fractal geometric generalization. With this methodology, it was founded that the occupation space possibilities in the stenotic process are finite and that 69,249 arterial prototypes are obtained as a total.Conclusions: The Intrinsic Mathematical Harmony reveals a supra-molecular geometric self-organization, where the finite and discrete fractal dimensions of arterial layers evaluate objectively the arterial stenosis and restenosis process. © 2010 Rodríguez et al; licensee BioMed Central Ltd. Source


Tena-Betancourt E.,National Autonomous University of Mexico | Tena-Betancourt C.A.,National Autonomous University of Mexico | Tena-Betancourt C.A.,INC Ignacio Chavez | Zuniga-Munoz A.M.,INC Ignacio Chavez | And 6 more authors.
Journal of the American Association for Laboratory Animal Science | Year: 2014

Extrauterine pregnancy (EP) is infrequent in mammalian species and occurs when fertilized ova implant and develop outside the uterus. A common outcome is abdominal pregnancy resulting in mummified fetuses (lithopedia). Here we describe an unusual case of abdominal pregnancy with early and near full-term lithopedia. Macroscopic findings supported the diagnosis of lithopedia with distinct age differences and facilitated further characterization of primary ectopia and risk factors leading to this occurrence. Copyright 2014 by the American Association for Laboratory Animal Science. Source

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