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Your search keyword '"A. Alonso-Lomillo"' showing total 146 results
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146 results on '"A. Alonso-Lomillo"'

22. A Chronoamperometric Screen Printed Carbon Biosensor Based on Alkaline Phosphatase Inhibition for W(VI) Determination in Water, Using 2-Phospho-l-Ascorbic Acid Trisodium Salt as a Substrate

Author

Ana Lorena Alvarado-Gámez, María Asunción Alonso-Lomillo, Olga Domínguez-Renedo, and María Julia Arcos-Martínez

Subjects
alkaline phosphatase, chronoamperometry, 2-phospho-l-ascorbic acid trisodium salt, screen printed carbon electrode, tungsten, Chemical technology, TP1-1185
Abstract

This paper presents a chronoamperometric method to determine tungsten in water using screen-printed carbon electrodes modified with gold nanoparticles and cross linked alkaline phosphatase immobilized in the working electrode. Enzymatic activity over 2-phospho-l-ascorbic acid trisodium salt, used as substrate, was affected by tungsten ions, which resulted in a decrease of chronoamperometric current, when a potential of 200 mV was applied on 10 mM of substrate in a Tris HCl buffer pH 8.00 and 0.36 M of KCl. Calibration curves for the electrochemical method validation, give a reproducibility of 5.2% (n = 3), a repeatability of 9.4% (n = 3) and a detection limit of 0.29 ± 0.01 µM. Enriched tap water, purified laboratory water and bottled drinking water, with a certified tungsten reference solution traceable to NIST, gave a recovery of 97.1%, 99.1% and 99.1% respectively (n = 4 in each case) and a dynamic range from 0.6 to 30 µM. This study was performed by means of a Lineweaver–Burk plot, showing a mixed kinetic inhibition.

Published
2015
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23. Acetylcholinesterase Inhibition-Based Biosensor for Aluminum(III) Chronoamperometric Determination in Aqueous Media

Author

Miriam Barquero-Quirós, Olga Domínguez-Renedo, Maria Asunción Alonso-Lomillo, and María Julia Arcos-Martínez

Subjects
acetylcholinesterase, biosensor, aluminum, acetylthiocholine iodide, screen-printed electrodes, gold nanoparticles, Chemical technology, TP1-1185
Abstract

A novel amperometric biosensor for the determination of Al(III) based on the inhibition of the enzyme acetylcholinesterase has been developed. The immobilization of the enzyme was performed on screen-printed carbon electrodes modified with gold nanoparticles. The oxidation signal of acetylthiocholine iodide enzyme substrate was affected by the presence of Al(III) ions leading to a decrease in the amperometric current. The developed system has a detection limit of 2.1 ± 0.1 μM for Al(III). The reproducibility of the method is 8.1% (n = 4). Main interferences include Mo(VI), W(VI) and Hg(II) ions. The developed method was successfully applied to the determination of Al(III) in spiked tap water . The analysis of a certified standard reference material was also carried out. Both results agree with the certified values considering the respective associated uncertainties.

Published
2014
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29. A Disposable Alkaline Phosphatase-Based Biosensor for Vanadium Chronoamperometric Determination

Author

Ana Lorena Alvarado-Gámez, María Asunción Alonso-Lomillo, Olga Domínguez-Renedo, and María Julia Arcos-Martínez

Subjects
alkaline phosphatase, biosensor, gold nanoparticles, 4-nitrophenyl phosphate, screen printed electrode, vanadium, water analysis, Chemical technology, TP1-1185
Abstract

A chronoamperometric method for vanadium ion determination, based on the inhibition of the enzyme alkaline phosphatase, is reported. Screen-printed carbon electrodes modified with gold nanoparticles were used as transducers for the immobilization of the enzyme. The enzymatic activity over 4-nitrophenyl phosphate sodium salt is affected by vanadium ions, which results in a decrease in the chronoamperometric current registered. The developed method has a detection limit of 0.39 ± 0.06 µM, a repeatability of 7.7% (n = 4) and a reproducibility of 8% (n = 3). A study of the possible interferences shows that the presence of Mo(VI), Cr(III), Ca(II) and W(VI), may affect vanadium determination at concentration higher than 1.0 mM. The method was successfully applied to the determination of vanadium in spiked tap water.

Published
2014
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