Vagner Bezerra dos Santos

Bio: Vagner Bezerra dos Santos is an academic researcher from Federal University of Pernambuco. The author has contributed to research in topics: Detection limit & Capillary electrophoresis. The author has an hindex of 16, co-authored 54 publications receiving 791 citations. Previous affiliations of Vagner Bezerra dos Santos include University of São Paulo & Federal University of São Carlos.

Differential Pulse Voltammetric Determination of Paraquat Using a Bismuth‐Film Electrode

Abstract: A bismuth-film electrode (BiFE) ex situ electrochemically deposited onto a copper substrate has been presented for paraquat determination. The bismuth film was electrochemically deposited at an applied potential of � 0.18 V vs. Ag/ AgCl (3.0 M KCl) for 200 s. The analytical curve was linear in the paraquat concentration range from 6.6 � 10 � 7 Mt o 4.8 � 10 � 5 M with a limit of detection of 9.3 � 10 � 8 M. The method presented satisfactory results at a confidence level of 95% and the performance was evaluated in water samples.

A digital image-based method employing a spot-test for quantification of ethanol in drinks

Abstract: A low-cost analytical method for quantification of ethanol in drinks based on the combination of a colorimetric spot-test and a digital image-based (DIB) method is proposed. The digital images from spot-test reactions were captured using a digital camera in a portable plastic chamber designed with internal lighting control. The images were decomposed by a RGB approach using freely available software. The R channel showed the best linearity, with two linear ethanol concentration ranges: from 1.0% to 20.0% v/v (r = 0.999) and from 25.0% to 50.0% v/v (r = 0.980), with limits of detection and quantification of 0.25% and 0.85% v/v, respectively, for the first analytical curve. The developed method was applied to quantification of ethanol in alcoholic drink samples with results in close agreement with those obtained using a spectrophotometric method at a confidence level of 95%, and with low waste generation (835 μL/spot-test). Thus, we believe that the DIB method can be useful with regard to environmental and social impacts, once the method has a low waste generation and uses an easily available instrumentation with potential for in situ determination during the alcoholic beverage production and its quality control.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Random graphs

Abstract: We will review some of the major results in random graphs and some of the more challenging open problems. We will cover algorithmic and structural questions. We will touch on newer models, including those related to the WWW.

Impact of Biogenic Amines on Food Quality and Safety.

Abstract: Today, food safety and quality are some of the main concerns of consumer and health agencies around the world. Our current lifestyle and market globalization have led to an increase in the number of people affected by food poisoning. Foodborne illness and food poisoning have different origins (bacteria, virus, parasites, mold, contaminants, etc.), and some cases of food poisoning can be traced back to chemical and natural toxins. One of the toxins targeted by the Food and Drug Administration (FDA) and European Food Safety Authority (EFSA) is the biogenic amine histamine. Biogenic amines (BAs) in food constitute a potential public health concern due to their physiological and toxicological effects. The consumption of foods containing high concentrations of biogenic amines has been associated with health hazards. In recent years there has been an increase in the number of food poisoning cases associated with BAs in food, mainly in relation to histamines in fish. We need to gain a better understanding of the origin of foodborne disease and how to control it if we expect to keep people from getting ill. Biogenic amines are found in varying concentrations in a wide range of foods (fish, cheese, meat, wine, beer, vegetables, etc.), and BA formation is influenced by different factors associated with the raw material making up food products, microorganisms, processing, and conservation conditions. Moreover, BAs are thermostable. Biogenic amines also play an important role as indicators of food quality and/or acceptability. Hence, BAs need to be controlled in order to ensure high levels of food quality and safety. All of these aspects will be addressed in this review.

A review of extraction, analytical and advanced methods for determination of pesticides in environment and foodstuffs

Abstract: Pesticides are widely applied to prevent unwanted pests from attacking crops and livestock which led to their access into the environment. Overuses of pesticides in environment are presence of pesticide residues and their metabolites that are causing serious detrimental effects on human health and all other living organisms. Several severe diseases (Cancer, chronic obstructive pulmonary disease, birth defects, infertility) and more damages of human health are associated with the exposure of pesticides. The maximum residue limits for pesticides have been regulated by the Codex Alimentarius Commission and European Union to protect human health. Thus, monitoring these compounds is extremely important to ensure that only permitted levels of pesticide are consumed. To date, several techniques have been developed for pesticide detection, from conventional analytical to advanced detection techniques. The conventional analytical methods are gas chromatography and high performance liquid chromatography coupled with various detectors involved a sample preparation step prior to further analysis. Advanced detection methods refer to the sensors development such as electrochemical, optical, piezoelectric and molecular imprinted polymer. In this review, we summarized and explained the available analytical and advanced methods for determination of pesticides compound in environment and foodstuffs. Also, pesticides classification and its toxicity, and available extraction methods are briefly discussed.