
Vagner Bezerra dos SantosFederal University of Pernambuco | UFPE · Departamento de Química Fundamental
Vagner Bezerra dos Santos
PHD
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82
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Introduction
Professor and Researcher in Analytical Chemistry with emphasis at Analytical Instrumentation, Chromatography, Mass Spectrometry, Electroanalytical Methods, Deep Eutectic Solvent, Quantum Dots, Digital Image Methods and Artificial Intelligence (AI).
Additional affiliations
June 2016 - present
September 2013 - present
August 2007 - August 2013
Publications
Publications (82)
This review details recent advances in digital imaging (DI) methods for the development of analytical methodologies combining quantum dots (QDs). The art-of-art, treatment of data, apparatus, software, chemical sensors, and...
The electrooxidation of 3‐methyladenine (3‐mAde) in aqueous electrolytes on the glassy carbon electrode (GCE) was investigated by voltammetric techniques and electrochemical impedance spectroscopy (EIS). Different experimental factors were explored, such as the influence of concentration, composition and pH of the medium, mass transport, adsorption...
We report on the advantages of a green method to detect surfactants in environmental water samples. The approach is based on the use of a hydrophobic natural deep eutectic solvent (NADES) to extract the complexes formed by the surfactants and methylene blue. The concentration of the surfactant is then determined by measuring the color intensity in...
Surfactants from detergents, when inadequately treated in sewage treatment plant, are carried away into estuaries, resulting in the contamination of aquatic environments. It is thus necessary to develop rapid and...
BACKGROUND
This work proposes the use of a simple, inexpensive method for the hydrothermal synthesis of fluorescent carbon dot nanoparticles (CDs) from rice starch aimed at the determination of Hg²⁺ in water. The proposed method involved using a paper‐based analytical device coupled to a 3D plate, with a UV‐LED chamber and a smartphone for the acqu...
In the present work, we report the development of a novel cotton thread-based colorimetric sensor modified by carboxymethylcellulose (CMC) and cuprizone (CPZ) with smartphone detection and its application for the quantitative determination of cupric ions in water and cachaça. The cotton thread/smartphone detection-based colorimetric method is an ea...
This work describes the analysis of molecular spectroscopy in the UV/Vis region, as well as the study of transmittance, absorption, and reflectance phenomena in an undergraduate class using an LED (light emitting diodes)-photometer and digital image-based (DIB) method using a smartphone to compare with a benchtop spectrophotometer and literature da...
The present work describes a laboratory-on-a-drone (Lab-on-a-Drone) developed to perform in-situ detection of contaminants in environmental water samples. Toward this goal, the system was mounted on an unmanned aerial vehicle...
The present study reports, for the first time, the development and application of a highly efficient method based on digital imaging analysis for the simultaneous determination of Cu2+ and furfural in cachaça samples using a two-phase system and chemometrics tools. Furfural reacts with aniline in an acidic medium to form a Schiff base, which exhibi...
Given the importance of identifying the presence of biomarkers of human diseases in DNA samples, the main objective of this work was to investigate, for the first time, the electro-catalytic oxidation of 7-methyl-guanine (7-mGua) and 5-methyl-cytosine (5-mCyt) on a boron doped diamond electrode pre-treated cathodically (red-BDDE), using differentia...
In this work an unmanned aerial vehicle (UAV) was adapted to be used as an environmental tool to collect water samples of sea, estuary, and mangrove for further analysis by gas chromatography with a mass detector (GC-MS). The sampling automated system was based on a microcontroller, a solenoid valve, and a peristaltic mini-pump that was coupled to...
In this work, a simple, low-cost and easy-to-handle analytical procedure based on carbon quantum dots (CQDs) is proposed to check commercially available formulated microbicides that is used to mitigate the...
The anodic behavior of the isomers meta-, ortho- and para-tyrosine (m-, o-, p-Tyr) and of phenylalanine in aqueous support electrolytes, with different pH values, on the glassy carbon electrode (GCE), were investigated and compared using cyclic and differential pulse voltammetry. The electrochemical behavior of 3-chloro-tyrosine (3-Cl-Tyr) in diffe...
In the present work, we proposed for the first time a simple and low-cost fluorometric method based on digital image using a UV-LED chamber and a 3D platform made of biodegradable polyacid lactic (PLA) and carbon dots (CDs) obtained from rice functionalized with cuprizone for the determination of Cu²⁺ in sugar cane spirits, using a paper-based devi...
In the present work a voltammetric method was developed for in situ detection of 2,4-dichlorophenoxyacetic acid (2,4-D) in environmental water samples, using a compact and lightweight electrochemical cell using a fused deposition modeling (FDM) 3D printer with biodegradable polylactic acid filament, and a boron-doped diamond electrode (BDDE). The s...
This paper reports the development and application of a low-cost multifunctional webcam spectrophotometer for the conduct of molecular absorption and fluorometric measurements. The equipment, which costs approximately US$20 to be fabricated, consists of a webcam, a diffraction grating, and a slit, all positioned inside an MDF box. Spectral measurem...
In this work we propose for the first time, a paper-based test strip to analyse Cu²⁺ content in sugar cane spirits, which, due to its simplicity, high portability and fast analytical response (3 minutes), can be easily applied to in situ analyses by producers. The test strip was developed aiming: i) identify qualitatively the Cu²⁺ content in sugar...
In this work, voltammetric methods were applied using a boron-doped diamond electrode (BDD) to detect Picloram (PCR), a very toxic and persistent herbicide. The method was applied to investigate environmental waters in the Amazon. In this context, an environmental-friendly method was developed using a miniaturized BDD electrode, and a compact elect...
For the first time, a method is proposed for colorimetric determination of reducing sugars in cachaça employing digital image and a smartphone as detector. The method was based on the reduction of Cu(II) to Cu(I) by sugars and followed by the formation of a colored Cu(I)-Neocuproine complex. A calibration curve was linear from 0.1 to 15 g L⁻¹ for g...
A digital image-based (DIB) method for fluorometric detection was developed using an ultraviolet (UV) chamber and a spot test platform made with a 3D printer. A smartphone was used as the detector to quantify quinine in commercial tonic beverage samples. The free OpenSCAD CAD program and a Prusa i3 3D printer were used for the construction of the c...
The concentrations of theobromine (TB) and caffeine (CF) together with other substances such as phenolic compounds, contribute to the perception of the bitter taste characteristic of fermented and unfermented Amazonian cocoa samples and their edible derivatives, such as chocolates. Thus, an analytical method based on square wave voltammetry (SWV) w...
A new method to determine the total titratable acidity of orange, lemon and passion fruit, based on a spot test obtained from digital images and using anthocyanins as the biodegradable indicator, is presented for the first time. The colorimetric reactions were carried out by acid-base titration on a microscale, employing anthocyanin with a micropla...
A new, simple, and low residue analytical method is proposed to check the conformity of bleach products containing hypochlorite. The method is economical and environmentally friendly because it uses low cost materials based on natural indicators and generates only 600 μL of waste per test and it allows 12 analyses within 5 min using only one digita...
In this work, we propose a method that employed a smartphone to capture images obtained from a colorimetric spot test to determine ascorbic acid (AA) in Brazilian Amazon native and exotic fruits. The spot test reaction was based on reduction of Fe(III) by AA and further complexation with 1,10-phenanthroline. After optimization, the limit of detecti...
Among the amines that have been systematically applied for CO2 capture, several alkanolamines have been proved to be very effective. Although the formation of carbamates – the reaction product of CO2 and the amine group – is recognized as the most important process, the behavior of a tertiary alkanolamine cannot be explained, because a carbamate ca...
A low-cost and portable LED-based photometer was developed and applied for in situ determination of copper in sugarcane spirit. The determination was based on the chelation reaction between copper(II) and cuprizone (bis(cyclohexanone)oxalyldihydrazone). After optimizing the best experimental variables, a dynamic linear range to determine copper(II)...
A análise de imagens digitais é um método analítico baseado na decomposição da imagem, cujos os valores RGB variam proporcionalmente com a concentração do analito. Para a determinação de etanol, empregou-se a reação de óxido-redução na qual o cromo (VI) é reduzido a cromo (III) ou cromo (II), sendo o etanol oxidado a aldeído acético, gerando mudanç...
A low-cost and portable LED photometer was developed and applied for the in situ determination of urea in milk. The determination was based on Berthelot’s reaction. After optimization, the best experimental variables, the detection limit and quantification limit were 1.8 × 10⁻⁴ and 8.0 × 10⁻⁴ mol L⁻¹, respectively. The percentage recovery varied be...
Aqueous extract of macerated Vochysia rufa stem bark has been commonly used in the treatment of diabetes. Therefore, we evaluated the antihyperglycemic and antioxidant effects of an extract of V. rufa on the pancreata of streptozotocin (STZ)-induced diabetic rats. Animals received one of the following treatments daily by oral gavage: water (diabeti...
The detection of coffee adulteration with soybean and corn by capillary electrophoresis-tandem mass spectrometry was accomplished by evaluating the monosaccharides profile obtained after acid hydrolysis of the samples. The acid hydrolysis, using H2SO4 as a catalyst, increases the ionic strength of the sample impairing the electrophoretic separation...
A simple, accurate, and low-cost analytical procedure for methanol determination in sugarcane spirits (cachaça) employing analysis of digital images is presented. A portable system with cheap materials and lighting system to obtain images from a smartphone was built and an RGB system was used for analytical purposes. The reaction for determination...
In this work the development and validation of analytical methodology for determination of copper in sugarcane spirit samples is carried out. The digital image based (DIB) method was applied along with spot test from the colorimetric reaction employing the RGB color model. For the determination of copper concentration, it was used the cuprizone - a...
In the textile industry, detecting aromatic amines derived from banned azo dyes is important in chemical safety control. To that end, we have developed a method using capillary electrophoresis in tandem with mass spectrometry (CE-MS/MS) for the determination of 4,4´-oxydianiline, 4,4'-diaminodiphenylmethane, and 4-chloro-2-methylaniline in fabric s...
A novel, simple, and low-cost analytical procedure for in situ in situ furfural determination in sugarcane spirit (cachaça) samples based on the combination of a colorimetric spot test and a digital image-based (DIB) method is proposed. Cachaça is the most consumed beverage in Brazil and the fourth in the world, and furfural is a contaminant that d...
A capillary electrophoresis tandem mass spectrometry (CE-MS/MS) method for the determination of four different sulfonamide antibiotics in commercial veterinary formulations has been developed. The samples were homogenized, solubilized in methanol, diluted in H 2 O/methanol (50:50, v/v), filtered, and injected, followed by electrophoretic separation...
A capillary electrophoresis tandem mass spectrometry (CE-MS/MS) method for the determination of four different sulfonamide antibiotics in commercial veterinary formulations has been developed. The samples were homogenized, solubilized in methanol, diluted in H 2 O/methanol (50:50, v/v), filtered, and injected, followed by electrophoretic separation...
A capillary electrophoresis tandem mass spectrometry (CE-MS/MS) method was developed for the simultaneous determination of amphetamine (AM), methamphetamine (MAM), methylenedioxyamphetamine (MDA), methylenedioxymethamphetamine (MDMA), methylenedioxyethylamphetamine (MDEA), and phentermine (PTM) in urine. The urine samples were submitted to a modifi...
Hemiesters of carbonic acid can be freely formed in aqueous media containing HCO3(-)/CO2 and mono- or poly-hydroxy compounds. Herein, (13)C NMR spectroscopy was used to identify isomers formed in aqueous solutions of glycerol (a prototype compound) and seven carbohydrates, as well as to estimate the equilibrium constant of formation (Keq). Although...
A methodology using capillary electrophoresis with tandem mass spectrometry detection (CE-MS/MS) was developed, validated, and applied to determine the cocaine content of seized drugs. The cocaine separation among other concomitants by capillary electrophoresis was achieved in just 4.0 minutes using 30 mM ammo-nium formate, pH 6.5, as a background...
A novel flow injection system for the determination of captopril in pharmaceutical formulations is described. Nitroprusside was employed as a new, nontoxic reagent. Captopril reacted with nitroprusside in basic solution to yield a red chromophore with maximum absorbance at 521 nm. The calibration relationship was linear for concentrations from 3.0...
Biogenic amines are important indicators of freshness and quality in food. This application note presents the determination of 11 biogenic amines (spermine, spermidine, putrescine, histamine, cadaverine, agmatine, 2-phenyl-ethylamine, tyramine, tryptamine, urocanic acid, and serotonin) by capillary electrophoresis-tandem mass spectrometry (CE-MS/MS...
In this study, we present a simple chromatographic paper-based colorimetric assay for the analysis of selected food compounds. The biochemical principle utilises enzymes from the dehydrogenase family coupled with diaphorase in the presence of a tetrazolium dye, MTT, and NAD +. The colored reaction product that developed on the surface of the chroma...
A novel, simple and low-cost analytical procedure for sulfite determination in beverage samples is presented. The approach proposed consists of image capture from a sulfite colorimetric reaction, using a system built with low-cost materials for luminosity control and digital image decomposition into the primary colors Red (R), Green (G) and Blue (B...
Microcontrolled systems coupled biosensors have attracted attention. Here, we describe an automated and portable microcontrolled pumping flow system (μC-PFS) developed to biosensing application. The flow system is fully automatic, portable, it works in battery module and it dispenses the use of microcomputer and the manual operations. This device p...
A compact environmentally friendly microcontrolled microfluidic device ideal for in situ phosphate determination was developed based on a microsystem based on low-temperature co-fired ceramics (LTCC) coupled to a light-emitting diode (LED)–photometer with a multicommutation flow analysis (MCFA) approach. The experimental parameters of the MCFA anal...
This application note describes a fast analytical method for determination of halosulfuron-methyl using QuEChERS and capillary electrophoresis tandem mass spectrometry (CE/MS/MS). The method was developed and validated for halosulfuron-methyl in green and yellow bell peppers. It showed good linearity (R 2 > 0.999) from 5.0 to 500 ppb for the analyt...
Recebido em 27/4/11; aceito em 5/10/11; publicado na web em 4/1/12 This study reports on the construction of a turbidimeter employing light emitting diodes as radiation source at a wavelength of 405 nm, a photodiode as detector, a temperature sensor and a microcontroller used for data acquisition and processing. The turbidimeter was applied to dete...
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 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...
An electrochemical analyzer based on a potentiostat/galvanostat (PG004) was developed and
applied to perform in situ Pb2+ and Cd2+ determination in water samples with on-line data
transmission, and a global positing system (GPS) to acquire the geographical coordinate of the place
being monitored. For this, a flow-batch analysis (FBA) and a thermost...
Supplementary data from: An electrochemical analyzer for in situ flow determinations of Pb(II) and Cd(II) in lake water with on-line data transmission and a global positing system
A capillary electrophoresis-tandem mass spectrometry (CE-MS/MS) method for the determination of halosulfuron-methyl (HSU) residue in samples of sugarcane juice and tomato is introduced and validated. The samples were submitted to a QuEChERS extraction procedure followed by electrophoretic separation in NH4HCO3 electrolyte (adjusted to pH 8.5) and d...
A versatile and robust thermostated electrochemical flow cell (EFC) with a boron-doped diamond electrode (BDD) detector was employed to perform two distinct flow-injection electrochemical approaches. In the first, a differential pulse anodic stripping voltammetry (DPASV) using a flow-batch analysis (FBA) is proposed. In the second, a multiple pulse...
Fig. S1. Flow diagram for the FBA-DPASV. The symbols between the pulses represent a group of pulses applied at a time interval. The steps are described as: filling the channels (1), addiction of H 2 SO 4 solution (2), temperature control (3), APT and CPT (4), drainage/air (5), cleaning (6), drainage/air (7), addition of blank (8), addition of Zn 2+...
Electrospray ionization (ESI) sources continuously consume the liquid at the tip of the capillary, which causes the dragging of the BGE. The laminar nature of this flow causes the broadening of the peaks and loss of separation efficiency. The usual solution for this problem is to compensate this phenomenon by reducing the pressure at the inlet vial...
RSC Advances This is an Accepted Manuscript, which has been through the Royal Society of Chemistry peer review process and has been accepted for publication. Accepted Manuscripts are published online shortly after acceptance, before technical editing, formatting and proof reading. Using this free service, authors can make their results available to...
An automated flow analyzer based on low temperature co-fired ceramic (LTCC), a solid-phase reactor (SPR) and a low-cost photometer was designed for ascorbic acid (AA) determination in pharmaceutical formulations. It consists of a peristaltic pump, three-way solenoid valves, SPR to chemically convert Cu(II) into Cu(I), and a LTCC device for mixing t...
In this work, an analytical microsystem based on LTCC (low-temperature co-fired ceramic) technology with monolithic incorporation of an optical flow cell for determination of dipyrone in pharmaceuticals is described. The detection system is based on the formation of a blue chromophore between dipyrone and Fe(III) photometrically monitored at 630 nm...
Recebido em 27/4/11; aceito em 5/10/11; publicado na web em 4/1/12 This study reports on the construction of a turbidimeter employing light emitting diodes as radiation source at a wavelength of 405 nm, a photodiode as detector, a temperature sensor and a microcontroller used for data acquisition and processing. The turbidimeter was applied to dete...