Claudimir Lago | Universidade de São Paulo (original) (raw)
Papers by Claudimir Lago
ELECTROPHORESIS, 2004
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ELECTROPHORESIS, 2012
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Analytical Chemistry, 2012
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Analytical Methods, 2012
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Quim Nova, 1998
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Quim Nova, 2003
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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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Computers & Chemistry, 1991
ABSTRACT
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Química Nova, 2006
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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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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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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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Talanta, 2005
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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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Química Nova, 2003
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Química Nova, 2002
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Química Nova, 1998
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Química Nova, 2007
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ELECTROPHORESIS, 2004
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ELECTROPHORESIS, 2012
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Analytical Chemistry, 2012
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Analytical Methods, 2012
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Quim Nova, 1998
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Quim Nova, 2003
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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
Bookmarks Related papers MentionsView impact
Computers & Chemistry, 1991
ABSTRACT
Bookmarks Related papers MentionsView impact
Química Nova, 2006
Bookmarks Related papers MentionsView impact
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
Bookmarks Related papers MentionsView impact
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
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
Talanta, 2005
Bookmarks Related papers MentionsView impact
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
Química Nova, 2003
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Química Nova, 2002
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Química Nova, 1998
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Química Nova, 2007
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