Total Trans Fatty Acid Analysis in Spreadable Cheese by Capillary Zone Electrophoresis

An alternative method for determination of total trans fatty acids expressed as elaidic acid by capillary zone electrophoresis (CZE) under indirect UV detection at 224 nm within an analysis time of 7.5 min was developed. The optimized running electrolyte includes 15.0 mmol L(-1) KH(2)PO(4)/Na(2)HPO(4) buffer (pH similar to 7.0), 4.0 mmol L(-1) SDBS, 8.0 mmol L(-1) Brij35, 45%v/v ACN, 8% methanol, and 1.5% v/v n-octanol. Baseline separation of the critical pair C18-9cis/C18:1-9t: with a resolution higher than 1.5 was achieved using C15:0 as the internal standard. The optimum capillary electrophoresis (CE) conditions for the background electrolyte were established with the aid of Raman spectroscopy and experiments of a 3(2) factorial design. After response factor (R(F)) calculations, the CE method was applied to total trans fatty acid (TTFA) analysis in a hydrogenated vegetable fat (HVF) sample, and compared with the American Oil Chemists` Society (AOCS) official method by gas chromatography (GC). The methods were compared with an independent sample t test, and no significant difference was found between CE and GC methods within the 95% confidence interval for six genuine replicates of TTFA analysis (p-value > 0.05). The CE method was applied to TTFA analysis in a spreadable cheese sample. Satisfactory results were obtained, indicating that the optimized methodology can be used for trans fatty acid determination for these samples.

Detection of adulterations in processed coffee with cereals and coffee husks using capillary zone electrophoresis

The proposed method for the identification of adulteration was based on the controlled acid hydrolysis of xylan and starch present in some vegetable adulterants, followed by the analysis of the resulting xylose and glucose, which are the monosaccharides that compose, respectively, the two polysaccharides. The acid hydrolysis with HCl increases the ionic strength of the sample, which impairs the electrophoretic separation. Thus, a neutralization step based on anion exchange resin was necessary. The best separations were obtained in NaOH 80 mmol/L, CTAB 0.5 mmol/L, and methanol 30% v/v. Because of the high value of pH, monosaccharides are separated as anionic species in such running electrolyte. The LOQ for both monosaccharides was 0.2 g for 100 g of dry matter, which conforms to the tolerable limits.

Environmental formaldehyde analysis by active diffusive sampling with a bundle of polypropylene porous capillaries followed by capillary zone electrophoretic separation and contactless conductivity detection

Compared to other volatile carbonylic compounds present in outdoor air, formaldehyde (CH2O) is the most toxic, deserving more attention in terms of indoor and outdoor air quality legislation and control. The analytical determination of CH2O in air still presents challenges due to the low-level concentration (in the sub-ppb range) and its variation with sampling site and time. Of the many available analytical methods for carbonylic compounds, the most widespread one is the time consuming collection in cartridges impregnated with 2,4-dinitrophenylhydrazine followed by the analysis of the formed hydrazones by HPLC. The present work proposes the use of polypropylene hollow porous capillary fibers to achieve efficient CH2O collection. The Oxyphan (R) fiber (designed for blood oxygenation) was chosen for this purpose because it presents good mechanical resistance, high density of very fine pores and high ratio of collection area to volume of the acceptor fluid in the tube, all favorable for the development of air sampling apparatus. The collector device consists of a Teflon pipe inside of which a bundle of polypropylene microporous capillary membranes was introduced. While the acceptor passes at a low flow rate through the capillaries, the sampled air circulates around the fibers, impelled by a low flow membrane pump (of the type used for aquariums ventilation). The coupling of this sampling technique with the selective and quantitative determination of CH2O, in the form of hydroxymethanesulfonate (HMS) after derivatization with HSO3-, by capillary electrophoresis with capacitively coupled contactless conductivity detection (CE-(CD)-D-4) enabled the development of a complete analytical protocol for the CH2O evaluation in air. (C) 2008 Published by Elsevier B.V.

Direct detection of underivatized chitooligosaccharides produced through chitinase action using capillary zone electrophoresis

Capillary electrophoresis with capacitively coupled contactless conductivity detection was successfully used to quantify N-acetylglucosamine and five N-acetyl-chitooligosaccharides (C2-C6) produced after reaction with a purified chitinase (TmChi) from Tenebrio molitor (Coleoptera). No derivatization process was necessary. The separation was developed using 10 mM NaOH with 10% (v/v) acetonitrile as background electrolyte and homemade equipment with a system that avoids the harmful effect of electrolysis. The limit of detection for all oligosaccharides was ca. 3 mu M, and the results indicated that the larger the oligosaccharide, the higher the sensitivity. Analysis of the chitooligosaccharides produced revealed that TmChi has an endolytic cleavage pattern with C5 as the best substrate (higher catalytic efficiency k(cat)/K-M) releasing C2 and C3. (c) 2007 Elsevier Inc. All rights reserved.

Determination of fluoroacetate and fluoride in blood serum by capillary zone electrophoresis using capacitively coupled contactless conductivity detection

Fluoroacetate is a highly toxic species naturally found in plants and in commercial products (compound 1080) for population control of several undesirable animal species. However, it is non-selective and toxic to many other animals including humans, and thus its detection is very important for forensic purposes. This paper presents a sensitive and fast method for the determination of fluoroacetate in blood serum using capillary electrophoresis with capacitively coupled contactless conductivity detection. Serum blood samples were treated with ethanol to remove proteins. The samples were analyzed in BGE containing 15 mmol/L histidine and 30 mmol/L gluconic acid (pH 3.85). The calibration curve was linear up to 75 mu mol/L (R(2) = 0.9995 for N = 12). The detection limit in the blood serum was 0.15 mg/kg, which is smaller than the lethal dose for humans and other animals. Fluoride, a metabolite of the fluoroacetate defluorination, could also be detected for levels greater than 20 mu mol/L, when polybrene was used for reversion of the EOF. CTAB and didecyldimethylammonium bromide are not useful for this task because of the severe reduction of the fluoride level. However, no interference was observed for fluoroacetate.

The Movement of the Gastrop Littorina Littorea in the Intertidal Zone during the Onset of Winter

The movement of the snail Littorina littoreaon the North Atlantic coast is poorly understood. Most research has concentrated on the vertical distribution of the snail, and suggests that it prefers the low intertidal zone where its food source is most plentiful. In the winter, this distribution is reinforced by a documented seaward migration of snails from the high intertidal zone in response to falling temperatures. From October 14, 2006 to January 22, 2007, I examined the individual movements and recovery of snails in response to the onset of winter. I proposed that falling water and air temperatures drive the majority of snail movement within the intertidal zone, and that water temperature had the greater effect. I also examined the possibility that, in addition to a seaward migration, winter weather patterns in the Gulf of Maine and their effect on the ocean may encourage the wintertime vertical distribution of snails. Finally, I examined the possibility that populations of snails in the comparatively inhospitable high intertidal zone may endure the winter if given access to proper resources.

De "l'ermite" à "zone" : une lecture d'alcools de Guillaume Apollinaire

Resumo não disponível.

Especulative (sic) attack on exchange rate target zone regime : the uncertainty case

We present a continuous time target zone model of speculative attacks. Contrary to most of the literature that considers the certainty case, i.e., agents know for sure the Central Bank behavior in the future, we build uncertainty into the madel in two different ways. First, we consider the case in whicb the leveI of reserves at which the central bank lets the regime collapse is uncertain. Alternatively, we ana1ize the case in which, with some probability, the government may cbange its policy reducing the initially positive trend in domestic credito In both cases, contrary to the case of a fixed exchange rate regime, speculators face a cost of launching a tentative attack that may not succeed. Such cost induces a delay and may even prevent its occurrence. At the time of the tentative attack, the exchange rate moves either discretely up, if the attack succeeds, or down, if it fails. The remlts are consistent with the fact that, typically, an attack involves substantial profits and losses for the speculators. In particular, if agents believed that the government will control fiscal imbalances in the future, or alternatively, if they believe the trend in domestic credit to be temporary, the attack is postponed even in the presence of a signal of an imminent collapse. Finally, we aIso show that the timing of a speculative attack increases with the width of the target zone.

Brazil’s 35 years-old quasi-stagnation: facts and theory

Brazil is growing around 1% per capita a year from 1981; this means for a country that is supposed to catch up, quasi-stagnation. Four historical new facts explain why growth was so low after the Real Plan: the reduction of public savings, and three facts that reduce private investments: the end of the unlimited supply of labor, a very high interest rate, and the 1990 dismantling of the mechanism that neutralized the Dutch disease, which represented a major competitive disadvantage for the manufacturing industry. New-developmental theory offers an explanation and two solutions for the problem, but does not underestimate the political economy problems involved

Economic stagnation and alternative development strategies

The focus of my paper is the presentation of some thoughts on overcoming economic stagnation, with reference to the case of Mexico. In Section 2, I will describe the reasons why the policies of financial opening based on the Washington Consensus create endogenous tendencies toward economic stagnation and overvaluation of currencies. Section 3 offers a concise outline of a possible alternative development project for Mexico. Section 4 presents some proposals regarding monetary, foreign exchange, and fiscal policy oriented toward reviving economic growth. Finally, in Section 5, I present some conclusions.

Note zone

Imagem componente do jogo “Musikinésia (http://www.loa.sead.ufscar.br/musikinesia.php)” desenvolvido pela equipe do Laboratório de Objetos de Aprendizagem da Universidade Federal de São Carlos (LOA/UFSCar).

Contamination of port zone sediments by metals from Large Marine Ecosystems of Brazil

Sediment contamination by metals poses risks to coastal ecosystems and is considered to be problematic to dredging operations. In Brazil, there are differences in sedimentology along the Large Marine Ecosystems in relation to the metal distributions. We aimed to assess the extent of Al, Fe, Hg, Cd, Cr, Cu, Ni, Pb and Zn contamination in sediments from port zones in northeast (Mucuripe and Pecem) and southeast (Santos) Brazil through geochemical analyses and sediment quality ratings. The metal concentrations found in these port zones were higher than those observed in the continental shelf or the background values in both regions. In the northeast, metals were associated with carbonate, while in Santos, they were associated with mud. Geochemical analyses showed enrichments in Hg, Cd, Cu, Ni and Zn, and a simple application of international sediment quality guidelines failed to predict their impacts, whereas the use of site-specific values that were derived by geochemical and ecotoxicological approaches seemed to be more appropriate in the management of the dredged sediments. (C) 2012 Elsevier Ltd. All rights reserved.

Nesting architecture and population structure of the fungus-growing ant Cyphomyrmex transversus (Formicidae: Myrmicinae: Attini) in the Brazilian coastal zone of Ilheus, Bahia

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)