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Pages-Rebull J, Sagristà G, Pérez-Ràfols C, Serrano N, Díaz-Cruz JM. Application of HPLC-UV combined with chemometrics for the detection and quantification of 'true cinnamon' adulteration. Talanta 2024; 271:125676. [PMID: 38266436 DOI: 10.1016/j.talanta.2024.125676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 01/11/2024] [Accepted: 01/13/2024] [Indexed: 01/26/2024]
Abstract
Cinnamon is one of the most popular spices used in cuisines worldwide. Among its different species, Ceylon cinnamon ("true cinnamon") is the one with the most health benefits due to its high concentration in the antioxidant eugenol and the ultra-low content of the hepatotoxic compound coumarin. However, the higher price of Ceylon cinnamon makes it vulnerable to fraudulent adulteration with more economic species of cinnamon, such as Cassia and Saigon. Thus, for the detection of frauds in cinnamon samples, a HPLC-UV method was developed for the determination of 4 characteristic cinnamon compounds: eugenol, cinnamaldehyde, coumarin and cinnamic acid. The obtained data were analyzed by PLS to attain not only the authentication of cinnamon species but also the detection and quantification of partial adulterations. Several mixtures prepared in the laboratory using different cinnamon powder samples considered 'pure' Ceylon, Cassia or Saigon were tested, concluding that the proposed approach allows a clear identification of Ceylon cinnamon and a suitable quantification of the Ceylon: non-Ceylon ratio regardless of the commercial sample selected (RMSE <0.06 for both training and test sets).
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Pages-Rebull J, Pérez-Ràfols C, Serrano N, del Valle M, Díaz-Cruz JM. Classification and authentication of spices and aromatic herbs by means of HPLC-UV and chemometrics. FOOD BIOSCI 2023. [DOI: 10.1016/j.fbio.2023.102401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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Sirin Ustabasi G, Bastos-Arrieta J, Pérez-Ràfols C, Serrano N, Díaz-Cruz JM. Considerations on the use of spectroelectrochemistry in reflection mode for quantitative analysis: Study of the Fe(III)/Fe(II) – orthophenanthroline system. Microchem J 2022. [DOI: 10.1016/j.microc.2022.107678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Tapia MA, Gusmão R, Pérez-Ràfols C, Subirats X, Serrano N, Sofer Z, Díaz-Cruz JM. Enhanced voltammetric performance of sensors based on oxidized 2D layered black phosphorus. Talanta 2022; 238:123036. [PMID: 34801894 DOI: 10.1016/j.talanta.2021.123036] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2021] [Revised: 10/29/2021] [Accepted: 11/03/2021] [Indexed: 11/29/2022]
Abstract
The exceptional properties of 2D layered black phosphorus (BP) make it a promising candidate for electrochemical sensing applications and, even though BP is considered unstable and tends to degrade by the presence of oxygen and moisture, its oxidation can be beneficial in some situations. In this work, we present an unequivocal demonstration that the exposition of BP-based working electrodes to normal ambient conditions can indeed be advantageous, leading to an enhancement of voltammetric sensing applications. This point was proved using a BP modified screen-printed carbon electrode (BP-SPCE) for the voltammetric determination of dopamine (DA) as a model target analyte. Oxidized BP-SPCE (up to 35% of PxOy at the surface) presented an enhanced analytical performance with a 5-fold and 2-fold increase in sensitivity, as compared to bare-SPCE and non-oxidized BP-SPCE stored in anhydrous atmosphere, respectively. Good detection limit, repeatability, reproducibility, stability, selectivity, and accuracy were also achieved. Overall, the results presented herein display the prominent possibilities of preparing and working with BP based-sensors in normal ambient settings and showcase their implementation under physiological conditions.
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Morris A, Serrano N, Díaz-Cruz JM, Bendavid A, Chen M, Vepsäläinen M. Vibrating boron-doped diamond electrode: A new, durable and highly sensitive tool for the detection of cadmium. Anal Chim Acta 2021; 1188:339166. [PMID: 34794577 DOI: 10.1016/j.aca.2021.339166] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 09/16/2021] [Accepted: 10/09/2021] [Indexed: 12/31/2022]
Abstract
In this paper, a vibrating boron-doped diamond (BDD) electrode electroanalytical device and respective method for the analysis of ultralow concentrations of Cd(II) in water were studied. The enhanced mass transfer on the electrode surface was studied using Ru(NH3)6Cl3. Vibration with 133 Hz frequency enhanced the Ru(III) to Ru(II) reduction by 92.6% compared to a static electrode. The peak current of the anodic stripping voltammetry (ASV) method employed was increased by a factor of 5.3 and 4.7 for 10 and 30 μg L-1 Cd(II) concentrations, respectively, when a frequency of 200 Hz was used. A calibration plot with two linear regions was resolved between 0.01 and 1 μg L-1 and 1-30 μg L-1 with the LOD and LOQ of 0.04 μg L-1 and 0.12 μg L-1, respectively. The applicability of the device and the respective method in the analysis of real environmental samples was successfully verified by analysis of river samples and comparing the results with the ICP analysis presenting high reproducibility and trueness. According to the results of this research, the vibrating BDD electrode with the ASV method has excellent analytical performance without surface modification or regular replacement or polishing of the electrode surface. Combining the exceptional electrochemical and chemical properties of BDD with enhanced mass transfer and signal strength of vibrating electrodes makes the system especially suitable for on-site and online analysis of heavy metals.
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Tapia MA, Gusmão R, Serrano N, Sofer Z, Ariño C, Díaz-Cruz JM, Esteban M. Phosphorene and other layered pnictogens as a new source of 2D materials for electrochemical sensors. Trends Analyt Chem 2021. [DOI: 10.1016/j.trac.2021.116249] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Serrano N, Pérez-Ràfols C, Ariño C, Esteban M, Manuel Díaz-Cruz J. MCR-ALS of voltammetric data for the study of environmentally relevant substances. Microchem J 2020. [DOI: 10.1016/j.microc.2020.105177] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Díaz-Cruz JM, Serrano N, Pérez-Ràfols C, Ariño C, Esteban M. Electroanalysis from the past to the twenty-first century: challenges and perspectives. J Solid State Electrochem 2020; 24:2653-2661. [PMID: 32837295 PMCID: PMC7306008 DOI: 10.1007/s10008-020-04733-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 06/15/2020] [Accepted: 06/16/2020] [Indexed: 12/14/2022]
Abstract
A personal mini-review is presented on the history of electroanalysis and on their present achievements and future challenges. The manuscript is written from the subjective view of two generations of electroanalytical chemists that have witnessed for many years the evolution of this discipline.
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Cetó X, Sánchez C, Serrano N, Díaz-Cruz JM, Núñez O. Authentication of paprika using HPLC-UV fingerprints. Lebensm Wiss Technol 2020. [DOI: 10.1016/j.lwt.2020.109153] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Tapia MA, Pérez-Ràfols C, Ariño C, Serrano N, Díaz-Cruz JM. New Approach to Multivariate Standard Addition Based on Multivariate Curve Resolution by Alternating Least-Squares: Application to Voltammetric Data. Anal Chem 2020; 92:3396-3402. [PMID: 31951120 DOI: 10.1021/acs.analchem.9b05477] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A multivariate version of the classical univariate standard addition method is proposed for the analysis of samples generating overlapping signals in the presence of notorious matrix effects. Unlike previous versions based on multivariate calibration by partial least-squares (PLS), the proposed strategy takes advantage of a self-modeling methodology: multivariate curve resolution by alternating least-squares (MCR-ALS) enhanced with signal shape constraints based on parametric functions. In this way, there is no need for the full multivariate response of a blank solution, and in multianalyte determinations, the standard additions can be made with a solution containing all of the analytes, which constitutes a clear advance as compared to PLS approach. The proposed method has been successfully tested in the voltammetric determination of hydroquinone and catechol in solutions of increasing complexity and appears to be a promising tool in the field of electroanalysis.
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Pérez-Ràfols C, Serrano N, Ariño C, Esteban M, Díaz-Cruz JM. Voltammetric Electronic Tongues in Food Analysis. SENSORS 2019; 19:s19194261. [PMID: 31575062 PMCID: PMC6806306 DOI: 10.3390/s19194261] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 09/25/2019] [Accepted: 09/28/2019] [Indexed: 02/06/2023]
Abstract
A critical revision is made on recent applications of voltammetric electronic tongues in the field of food analysis. Relevant works are discussed dealing with the discrimination of food samples of different type, origin, age and quality and with the prediction of the concentration of key substances and significant indexes related to food quality.
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Pérez-Ràfols C, Subirats X, Serrano N, Díaz-Cruz JM. New discrimination tools for harvest year and varieties of white wines based on hydrophilic interaction liquid chromatography with amperometric detection. Talanta 2019; 201:104-110. [DOI: 10.1016/j.talanta.2019.03.099] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Revised: 03/27/2019] [Accepted: 03/28/2019] [Indexed: 10/27/2022]
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Sunyer A, González-Navarro A, Serra-Roig MP, Serrano N, Díaz-Cruz MS, Díaz-Cruz JM. First application of carbon-based screen-printed electrodes for the voltammetric determination of the organic UV filters oxybenzone and octocrylene. Talanta 2019; 196:381-388. [DOI: 10.1016/j.talanta.2018.12.092] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Revised: 12/21/2018] [Accepted: 12/26/2018] [Indexed: 11/28/2022]
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Pérez-Ràfols C, Puy-Llovera J, Serrano N, Ariño C, Esteban M, Díaz-Cruz JM. A new multivariate standard addition strategy for stripping voltammetric electronic tongues: Application to the determination of Tl(I) and In(III) in samples with complex matrices. Talanta 2019; 192:147-153. [PMID: 30348371 DOI: 10.1016/j.talanta.2018.09.035] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 09/05/2018] [Accepted: 09/11/2018] [Indexed: 11/25/2022]
Abstract
A new multivariate standard addition strategy applicable to stripping methods was proposed as an extention of the classical univariate standard addition method for the resolution of complex samples involving overlapped peaks and complex matrices. The proposed strategy consists in alternate additions of the considered analytes and the further extrapolation to a simulated blank solution measured by skipping the preconcentration step (deposition time = 0). This calibration approach was successfully tested in tonic water samples spiked with Tl(I) and In(III) using a sensor array based on a SeCyst-SPCNFE and an ex-situ-BiSPCE, providing good concordance between replicates and much better accuracy than the usual multivariate external calibration method.
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Cetó X, Serrano N, Aragó M, Gámez A, Esteban M, Díaz-Cruz JM, Núñez O. Determination of HPLC-UV Fingerprints of Spanish Paprika ( Capsicum annuum L.) for Its Classification by Linear Discriminant Analysis. SENSORS (BASEL, SWITZERLAND) 2018; 18:E4479. [PMID: 30567367 PMCID: PMC6308838 DOI: 10.3390/s18124479] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 12/11/2018] [Accepted: 12/16/2018] [Indexed: 12/02/2022]
Abstract
The development of a simple HPLC-UV method towards the evaluation of Spanish paprika's phenolic profile and their discrimination based on the former is reported herein. The approach is based on C18 reversed-phase chromatography to generate characteristic fingerprints, in combination with linear discriminant analysis (LDA) to achieve their classification. To this aim, chromatographic conditions were optimized so as to achieve the separation of major phenolic compounds already identified in paprika. Paprika samples were subjected to a sample extraction stage by sonication and centrifugation; extracting procedure and conditions were optimized to maximize the generation of enough discriminant fingerprints. Finally, chromatograms were baseline corrected, compressed employing fast Fourier transform (FFT), and then analyzed by means of principal component analysis (PCA) and LDA to carry out the classification of paprika samples. Under the developed procedure, a total of 96 paprika samples were analyzed, achieving a classification rate of 100% for the test subset (n = 25).
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Serrano N, Cetó X, Núñez O, Aragó M, Gámez A, Ariño C, Díaz-Cruz JM. Characterization and classification of Spanish paprika (Capsicum annuum L.) by liquid chromatography coupled to electrochemical detection with screen-printed carbon-based nanomaterials electrodes. Talanta 2018; 189:296-301. [PMID: 30086921 DOI: 10.1016/j.talanta.2018.06.085] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Revised: 06/25/2018] [Accepted: 06/27/2018] [Indexed: 10/28/2022]
Abstract
Screen-printed electrodes based on graphite, carbon nanotubes, carbon nanofibers, and graphene were tested as amperometric detectors for the determination of phenolic compounds by high performance liquid chromatography (HPLC). The chromatographic performance as well as the obtained sensitivity, detection and quantification limits suggest that carbon nanofibers modified screen-printed electrode (SPCE-CNF) is the amperometric sensor that provides the best analytical performance. Upon this confirmation, chromatographic data obtained using SPCE-CNF were exploited by means of linear discriminant analysis (LDA) to successfully characterize and classify 96 Spanish paprika (Capsicum annuum L.) samples with different origin and type: from La Vera (including sweet, bittersweet and spicy types) and from Murcia (including sweet and spicy types).
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Puy-Llovera J, Pérez-Ràfols C, Serrano N, Díaz-Cruz JM, Ariño C, Esteban M. Selenocystine modified screen-printed electrode as an alternative sensor for the voltammetric determination of metal ions. Talanta 2017; 175:501-506. [DOI: 10.1016/j.talanta.2017.07.089] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 07/25/2017] [Accepted: 07/28/2017] [Indexed: 10/19/2022]
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Pérez-Ràfols C, Bastos-Arrieta J, Serrano N, Díaz-Cruz JM, Ariño C, de Pablo J, Esteban M. Ag Nanoparticles Drop-Casting Modification of Screen-Printed Electrodes for the Simultaneous Voltammetric Determination of Cu(II) and Pb(II). SENSORS 2017. [PMID: 28635631 PMCID: PMC5492509 DOI: 10.3390/s17061458] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
A new silver nanoparticle modified screen-printed electrode was developed and applied to the simultaneous determination of Pb(II) and Cu(II). Two different types of silver nanoparticles with different shapes and sizes, Ag nanoseeds and Ag nanoprisms, were microscopically characterized and three different carbon substrates, graphite, graphene and carbon nanofibers, were tested. The best analytical performance was achieved for the combination of Ag nanoseeds with a carbon nanofiber modified screen-printed electrode. The resulting sensor allowed the simultaneous determination of Pb(II) and Cu(II) at trace levels and its applicability to natural samples was successfully tested with a groundwater certified reference material, presenting high reproducibility and trueness.
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Turull M, Grmanova G, Dago À, Ariño C, Díez S, Díaz-Cruz JM, Esteban M. Phytochelatin synthesis in response to Hg uptake in aquatic plants near a chlor-alkali factory. CHEMOSPHERE 2017; 176:74-80. [PMID: 28259081 DOI: 10.1016/j.chemosphere.2017.02.092] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 02/16/2017] [Accepted: 02/17/2017] [Indexed: 06/06/2023]
Abstract
The effects of mercury (Hg) released from a chlor-alkali factory in aquatic plants along the Ebro River basin (NE Spain) were analysed considering the phytochelatins (PCn) and their isoforms content in these plants. These compounds were analyzed using HPLC with amperometric detection, and the macrophytes species Ceratophyllum demersum and Myriopyllum spicatum were collected in two sampling campaigns, autumn and spring, respectively. To correlate the PCn content in macrophytes with the Hg contamination, analysis of total Hg (THg) content in plants and suspended particulate matter, as well as the dissolved-bioavailable fraction of Hg in water measured by the diffusive gradient in thin film (DGT) technique were done. The results confirm the presence of PC2-Ala in extracts of C. demersum and PC2-desGly in M. spicatum, and the concentration of these thiol compounds depends clearly on the distance between the hot spot and the downstream sites: the higher the levels are, the closer the hot spot is. Since most of the Hg is hypothesized to be associated with SPM and transported downstream, our results of the DGT suggest that trace amounts of Hg in water can be released as free metal ions yielding a certain accumulation in plants (reaching the ppb level) that are enough for activation of induction of PCs. A few PCs species have been determined, at different seasons, indicating that they can be used as good indicators of the presence of bioavailable Hg in aquatic media throughout the year.
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Pérez-Ràfols C, Trechera P, Serrano N, Díaz-Cruz JM, Ariño C, Esteban M. Determination of Pd(II) using an antimony film coated on a screen-printed electrode by adsorptive stripping voltammetry. Talanta 2017; 167:1-7. [PMID: 28340698 DOI: 10.1016/j.talanta.2017.01.084] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Revised: 01/25/2017] [Accepted: 01/30/2017] [Indexed: 10/20/2022]
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Pérez-Ràfols C, Gómez A, Serrano N, Díaz-Cruz JM, Ariño C, Esteban M. A Voltammetric Electronic Tongue Based on Commercial Screen-printed Electrodes for the Analysis of Aminothiols by Differential Pulse Voltammetry. ELECTROANAL 2017. [DOI: 10.1002/elan.201700053] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Aragó M, Ariño C, Dago À, Díaz-Cruz JM, Esteban M. Simultaneous determination of hydroquinone, catechol and resorcinol by voltammetry using graphene screen-printed electrodes and partial least squares calibration. Talanta 2016; 160:138-143. [DOI: 10.1016/j.talanta.2016.07.007] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 06/30/2016] [Accepted: 07/03/2016] [Indexed: 10/21/2022]
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Pedroza RHP, Serrano N, Díaz-Cruz JM, Ariño C, Esteban M. Integration of Commercial Screen-printed Electrodes into a Voltammetric Electronic Tongue for the Analysis of Aminothiols. ELECTROANAL 2016. [DOI: 10.1002/elan.201501112] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Serrano N, Díaz-Cruz JM, Ariño C, Esteban M. Recent contributions to the study of phytochelatins with an analytical approach. Trends Analyt Chem 2015. [DOI: 10.1016/j.trac.2015.04.031] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Dago À, Navarro J, Ariño C, Díaz-Cruz JM, Esteban M. Carbon nanotubes and graphene modified screen-printed carbon electrodes as sensitive sensors for the determination of phytochelatins in plants using liquid chromatography with amperometric detection. J Chromatogr A 2015; 1409:210-7. [PMID: 26212803 DOI: 10.1016/j.chroma.2015.07.057] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Revised: 07/02/2015] [Accepted: 07/14/2015] [Indexed: 01/09/2023]
Abstract
Nanomaterials are of great interest for the development of electrochemical sensors. Multi-walled carbon nanotubes and graphene were used to modify the working electrode surface of different screen-printed carbon electrodes (SPCE) with the aim of improving the sensitivity of the SPCE and comparing it with the conventional glassy carbon electrode. To assay the usability of these sensors, a HPLC methodology with amperometric detection was developed to analyze several phytochelatins in plants of Hordeum vulgare and Glycine max treated with Hg(II) or Cd(II) giving detection limits in the low μmolL(-1) range. Phytochelatins are low molecular weight peptides with the general structure γ-(Glu-Cys)n-Gly (n=2-5) which are synthesized in plants in the presence of heavy metal ions. These compounds can chelate heavy metal ions by the formation of complexes which, are transported to the vacuoles, where the toxicity is not threatening. For this reason phytochelatins are essential in the detoxification of heavy metal ions in plants. The developed HPLC method uses a mobile phase of 1% of formic acid in water with KNO3 or NaCl (pH=2.00) and 1% of formic acid in acetonitrile. Electrochemical detection at different carbon-based electrodes was used. Among the sensors tested, the conventional glassy carbon electrode offers the best sensitivity although modification improves the sensitivity of the SPCE. Glutathione and several isoforms of phytochelatin two were found in plant extracts of both studied species.
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