Claudimir Lago | Universidade de São Paulo (original) (raw)

Papers by Claudimir Lago

Research paper thumbnail of Disposable twin gold electrodes for amperometric detection in capillary electrophoresis

ELECTROPHORESIS, 2004

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Research paper thumbnail of High-voltage power supplies to capillary and microchip electrophoresis

ELECTROPHORESIS, 2012

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Research paper thumbnail of From Sample Processing to Quantification: A Full Electrochemical Approach for Neutral Analyte Derivatization, Capillary Electrophoresis Separation, and Contactless Conductivity Detection

Analytical Chemistry, 2012

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Research paper thumbnail of Capacitively coupled contactless conductivity detection on microfluidic systems—ten years of development

Analytical Methods, 2012

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Research paper thumbnail of Automatiza��o de um destilador d'�gua

Quim Nova, 1998

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Research paper thumbnail of Aplica��es eletroanal�ticas com eletrodos de prata confeccionados a partir de CDs grav�veis

Quim Nova, 2003

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Research paper thumbnail of Determination of biogenic amines in beer and wine by capillary electrophoresis–tandem mass spectrometry

Journal of Chromatography A, 2015

A capillary electrophoresis-tandem mass spectrometry (CE-MS/MS) method for the simultaneous asses... more A capillary electrophoresis-tandem mass spectrometry (CE-MS/MS) method for the simultaneous assessment of nine biogenic amines (spermine, spermidine, putrescine, cadaverine, histamine, phenylethylamine, tryptamine, tyramine, and urocanic acid) in commercial samples of beer and wine is introduced. The samples were submitted to a simple clean-up step with poly(vinylpolypyrrolidone) followed by filtration. Electrophoretic separation in a polyvinyl alcohol (PVA)-coated capillary using 0.5molL(-1) acetic acid (pH 2.5) as background electrolyte and detection by electrospray-tandem mass spectrometry was employed. The range of the correlation coefficients of the calibration curves of the analyzed compounds was 0.996-0.999, and the limits of detection and limits of quantification were in the range of 1-2μgL(-1) and 3-8μgL(-1), respectively. The recovery values for samples spiked at three concentration levels (0.2, 0.5, and 1.0mgL(-1)) ranged from 87 to 113% with standard deviation not greater than 5.8%. The use of a PVA-coated silica capillary allows suppressing the electroosmotic flow and, consequently, increasing of the separation efficiency. The method was successfully used to determine biogenic amines in commercial samples of beer and wine.

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Research paper thumbnail of Integration of Microchips, Capillary Electrophoresis, and Electrochemical Detection with Robotic Platforms to Perform Remote Chemical Analysis

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Research paper thumbnail of New method of isotope pattern analysis

Computers & Chemistry, 1991

ABSTRACT

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Research paper thumbnail of Uso de frascos de polipropileno descartáveis no pré-tratamento de amostras de água para determinação de chumbo, cobre e mercúrio por voltametria de onda quadrada

Química Nova, 2006

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Research paper thumbnail of Uso de frascos de polipropileno descartáveis no pré-tratamento de amostras de água para determinação de chumbo, cobre e mercúrio por voltametria de onda quadrada

Quimica Nova, 2006

o C). This process is completed after one hour and allows the pretreatment of several samples sim... more o C). This process is completed after one hour and allows the pretreatment of several samples simultaneously. The accuracy was estimated using addition/recovery studies and certified water sample analysis, yielding an agreement near to 100%.

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Research paper thumbnail of Determination of Ca, K, Mg, Na, sulfate, phosphate, formate, acetate, propionate, and glycerol in biodiesel by capillary electrophoresis with capacitively coupled contactless conductivity detection

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Research paper thumbnail of Getting started with open-hardware: development and control of microfluidic devices

Electrophoresis, 2014

Understanding basic concepts of electronics and computer programming allows researchers to get th... more Understanding basic concepts of electronics and computer programming allows researchers to get the most out of the equipment found in their laboratories. Although a number of platforms have been specifically designed for the general public and are supported by a vast array of on-line tutorials, this subject is not normally included in university chemistry curricula. Aiming to provide the basic concepts of hardware and software, this article is focused on the design and use of a simple module to control a series of PDMS-based valves. The module is based on a low-cost microprocessor (Teensy) and open-source software (Arduino). The microvalves were fabricated using thin sheets of PDMS and patterned using CO2 laser engraving, providing a simple and efficient way to fabricate devices without the traditional photolithographic process or facilities. Synchronization of valve control enabled the development of two simple devices to perform injection (1.6 ± 0.4 μL/stroke) and mixing of differ...

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Research paper thumbnail of Determination of halosulfuron-methyl herbicide in sugarcane juice and tomato by capillary electrophoresis–tandem mass spectrometry

Food Chemistry, 2015

A capillary electrophoresis-tandem mass spectrometry (CE-MS/MS) method for the determination of h... more 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 detection by electrospray-tandem mass spectrometry. The total HSU migration took place in less than 3.5min, and the detection was accomplished by monitoring three fragmentation processes of this anion: m/z 435-182, 139, and 83. The R(2) values for concentrations up to 100ppb (μgkg(-1)) were, respectively, 0.992, 0.992, and 0.978. Recovery values for samples spiked at three concentration levels (10, 20 and 50ppb) were in the range of 96-104% with standard deviation not greater than 5.0%. The limit of detection for HSU in sugarcane juice and tomato was 2ppb for both samples.

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Research paper thumbnail of FIA-potentiometry in the sub-Nernstian response region for rapid and direct chloride assays in milk and in coconut water

Talanta, 2005

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Research paper thumbnail of Quantification of terbinafine in pharmaceutical tablets using capillary electrophoresis with contactless conductivity detection and batch injection analysis with amperometric detection

Talanta, 2012

Terbinafine hydrochloride (TerbHCl) is an allylamine derivative with fungicidal action, especiall... more Terbinafine hydrochloride (TerbHCl) is an allylamine derivative with fungicidal action, especially against dermatophytes. Different analytical methods have been reported for quantifying TerbHCl in different samples. These procedures require time-consuming sample preparation or expensive instrumentation. In this paper, electrochemical methods involving capillary electrophoresis with contactless conductivity detection, and amperometry associated with batch injection analysis, are described for the determination of TerbHCl in pharmaceutical products. In the capillary electrophoresis experiments, terbinafine was protonated and analyzed in the cationic form in less than 1 min. A linear range from 1.46 to 36.4 μg mL(-1) in acetate buffer solution and a detection limit of 0.11 μg mL(-1) were achieved. In the amperometric studies, terbinafine was oxidized at +0.85 V with high throughput (225 injection h(-1)) and good linear range (10-100 μmol L(-1)). It was also possible to determine the antifungal agent using simultaneous conductometric and potentiometric titrations in the presence of 5% ethanol. The electrochemical methods were applied to the quantification of TerbHCl in different tablet samples; the results were comparable with values indicated by the manufacturer and those found using titrimetry according to the Pharmacopoeia. The electrochemical methods are simple, rapid and an appropriate alternative for quantifying this drug in real samples.

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Research paper thumbnail of Confecção de um perfurador de lamínulas de vidro por corrosão ácida

Química Nova, 2003

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Research paper thumbnail of Módulo eletrônico de controle para válvulas solenóides

Química Nova, 2002

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Research paper thumbnail of Automatização de um destilador d'água

Química Nova, 1998

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Research paper thumbnail of Avaliação da composição química de águas do Sistema Guarapiranga: estudo de caso nos anos de 2002 e 2003

Química Nova, 2007

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Research paper thumbnail of Disposable twin gold electrodes for amperometric detection in capillary electrophoresis

ELECTROPHORESIS, 2004

Bookmarks Related papers MentionsView impact

Research paper thumbnail of High-voltage power supplies to capillary and microchip electrophoresis

ELECTROPHORESIS, 2012

Bookmarks Related papers MentionsView impact

Research paper thumbnail of From Sample Processing to Quantification: A Full Electrochemical Approach for Neutral Analyte Derivatization, Capillary Electrophoresis Separation, and Contactless Conductivity Detection

Analytical Chemistry, 2012

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Capacitively coupled contactless conductivity detection on microfluidic systems—ten years of development

Analytical Methods, 2012

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Research paper thumbnail of Automatiza��o de um destilador d'�gua

Quim Nova, 1998

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Research paper thumbnail of Aplica��es eletroanal�ticas com eletrodos de prata confeccionados a partir de CDs grav�veis

Quim Nova, 2003

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Determination of biogenic amines in beer and wine by capillary electrophoresis–tandem mass spectrometry

Journal of Chromatography A, 2015

A capillary electrophoresis-tandem mass spectrometry (CE-MS/MS) method for the simultaneous asses... more A capillary electrophoresis-tandem mass spectrometry (CE-MS/MS) method for the simultaneous assessment of nine biogenic amines (spermine, spermidine, putrescine, cadaverine, histamine, phenylethylamine, tryptamine, tyramine, and urocanic acid) in commercial samples of beer and wine is introduced. The samples were submitted to a simple clean-up step with poly(vinylpolypyrrolidone) followed by filtration. Electrophoretic separation in a polyvinyl alcohol (PVA)-coated capillary using 0.5molL(-1) acetic acid (pH 2.5) as background electrolyte and detection by electrospray-tandem mass spectrometry was employed. The range of the correlation coefficients of the calibration curves of the analyzed compounds was 0.996-0.999, and the limits of detection and limits of quantification were in the range of 1-2μgL(-1) and 3-8μgL(-1), respectively. The recovery values for samples spiked at three concentration levels (0.2, 0.5, and 1.0mgL(-1)) ranged from 87 to 113% with standard deviation not greater than 5.8%. The use of a PVA-coated silica capillary allows suppressing the electroosmotic flow and, consequently, increasing of the separation efficiency. The method was successfully used to determine biogenic amines in commercial samples of beer and wine.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Integration of Microchips, Capillary Electrophoresis, and Electrochemical Detection with Robotic Platforms to Perform Remote Chemical Analysis

Bookmarks Related papers MentionsView impact

Research paper thumbnail of New method of isotope pattern analysis

Computers & Chemistry, 1991

ABSTRACT

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Research paper thumbnail of Uso de frascos de polipropileno descartáveis no pré-tratamento de amostras de água para determinação de chumbo, cobre e mercúrio por voltametria de onda quadrada

Química Nova, 2006

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Research paper thumbnail of Uso de frascos de polipropileno descartáveis no pré-tratamento de amostras de água para determinação de chumbo, cobre e mercúrio por voltametria de onda quadrada

Quimica Nova, 2006

o C). This process is completed after one hour and allows the pretreatment of several samples sim... more o C). This process is completed after one hour and allows the pretreatment of several samples simultaneously. The accuracy was estimated using addition/recovery studies and certified water sample analysis, yielding an agreement near to 100%.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Determination of Ca, K, Mg, Na, sulfate, phosphate, formate, acetate, propionate, and glycerol in biodiesel by capillary electrophoresis with capacitively coupled contactless conductivity detection

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Getting started with open-hardware: development and control of microfluidic devices

Electrophoresis, 2014

Understanding basic concepts of electronics and computer programming allows researchers to get th... more Understanding basic concepts of electronics and computer programming allows researchers to get the most out of the equipment found in their laboratories. Although a number of platforms have been specifically designed for the general public and are supported by a vast array of on-line tutorials, this subject is not normally included in university chemistry curricula. Aiming to provide the basic concepts of hardware and software, this article is focused on the design and use of a simple module to control a series of PDMS-based valves. The module is based on a low-cost microprocessor (Teensy) and open-source software (Arduino). The microvalves were fabricated using thin sheets of PDMS and patterned using CO2 laser engraving, providing a simple and efficient way to fabricate devices without the traditional photolithographic process or facilities. Synchronization of valve control enabled the development of two simple devices to perform injection (1.6 ± 0.4 μL/stroke) and mixing of differ...

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Determination of halosulfuron-methyl herbicide in sugarcane juice and tomato by capillary electrophoresis–tandem mass spectrometry

Food Chemistry, 2015

A capillary electrophoresis-tandem mass spectrometry (CE-MS/MS) method for the determination of h... more 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 detection by electrospray-tandem mass spectrometry. The total HSU migration took place in less than 3.5min, and the detection was accomplished by monitoring three fragmentation processes of this anion: m/z 435-182, 139, and 83. The R(2) values for concentrations up to 100ppb (μgkg(-1)) were, respectively, 0.992, 0.992, and 0.978. Recovery values for samples spiked at three concentration levels (10, 20 and 50ppb) were in the range of 96-104% with standard deviation not greater than 5.0%. The limit of detection for HSU in sugarcane juice and tomato was 2ppb for both samples.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of FIA-potentiometry in the sub-Nernstian response region for rapid and direct chloride assays in milk and in coconut water

Talanta, 2005

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Quantification of terbinafine in pharmaceutical tablets using capillary electrophoresis with contactless conductivity detection and batch injection analysis with amperometric detection

Talanta, 2012

Terbinafine hydrochloride (TerbHCl) is an allylamine derivative with fungicidal action, especiall... more Terbinafine hydrochloride (TerbHCl) is an allylamine derivative with fungicidal action, especially against dermatophytes. Different analytical methods have been reported for quantifying TerbHCl in different samples. These procedures require time-consuming sample preparation or expensive instrumentation. In this paper, electrochemical methods involving capillary electrophoresis with contactless conductivity detection, and amperometry associated with batch injection analysis, are described for the determination of TerbHCl in pharmaceutical products. In the capillary electrophoresis experiments, terbinafine was protonated and analyzed in the cationic form in less than 1 min. A linear range from 1.46 to 36.4 μg mL(-1) in acetate buffer solution and a detection limit of 0.11 μg mL(-1) were achieved. In the amperometric studies, terbinafine was oxidized at +0.85 V with high throughput (225 injection h(-1)) and good linear range (10-100 μmol L(-1)). It was also possible to determine the antifungal agent using simultaneous conductometric and potentiometric titrations in the presence of 5% ethanol. The electrochemical methods were applied to the quantification of TerbHCl in different tablet samples; the results were comparable with values indicated by the manufacturer and those found using titrimetry according to the Pharmacopoeia. The electrochemical methods are simple, rapid and an appropriate alternative for quantifying this drug in real samples.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Confecção de um perfurador de lamínulas de vidro por corrosão ácida

Química Nova, 2003

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Módulo eletrônico de controle para válvulas solenóides

Química Nova, 2002

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Automatização de um destilador d'água

Química Nova, 1998

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Avaliação da composição química de águas do Sistema Guarapiranga: estudo de caso nos anos de 2002 e 2003

Química Nova, 2007

Bookmarks Related papers MentionsView impact