Germán Sanz Lobón

Efficient electrochemical remediation of microcystin-LR in tap water using designer TiO 2 @carbon electrodes

Microcystin-leucine arginine (MC-LR) is the most abundant and toxic secondary metabolite produced by freshwater cyanobacteria. This toxin has a high potential hazard health due to potential interactions with liver, kidney and the nervous system. The aim of this work was the design of a simple and environmentally friendly electrochemical system based on highly efficient nanostructured electrodes for the removal of MC-LR in tap water. Titania nanoparticles were deposited on carbon (graphite) under a simple and efficient microwave assisted approach for the design of the electrode, further utilized in the electrochemical remediation assays. Parameters including the applied voltage, time of removal and pH (natural tap water or alkaline condition) were investigated in the process, with results pointing to a high removal efficiency for MC-LR (60% in tap water and 90% in alkaline media experiments, under optimized conditions).

Rapid screening of agrochemicals by paper spray ionization and leaf spray mass spectrometry: which technique is more appropriate?

Paper Spray Ionization (PSI) and Leaf Spray (LS) are two new sources of ambient ionization mass spectrometry. In PSI, the sample is deposited on a triangular paper and ions are generated by applying a high voltage on a moistened paper with an organic protic solvent. The LS technique is a variant of PSI, where the paper is now substituted by the matrix itself to be studied, a triangular leaf. Both methods allow rapid and inexpensive analyses compared to traditional API techniques. In this work, both sources were applied to identify and quantify agrochemicals which are widely used in fruits and vegetables. The analytical performance of PS and LS techniques was evaluated from the construction of calibration curves in the positive ionization mode (PSI(+) and LS(+)) using atrazine, diuron and methomyl agrochemicals in arugula, basil, cabbage, lettuce and kale vegetable samples. The concentration ranged from 10 to 1000 ppb. Atrazine and diuron were used as internal standards, not requiring the use of deuterated standards. Both analytical methods demonstrated similar performance for the three agrochemicals with R2 > 0.99, and values of LOD and LOQ ranging from 1.23 to 25.00 and 4.12 to 83.33 ppb for PSI(+)-MS and from 0.03 to 36.00 and 0.11–120.00 ppb for LS(+)-MS. In almost all cases, these values were lower than the established MRLs (Maximum Residue Limits), which are 250 ppb for atrazine and 100 ppb for diuron and methomyl.

Electroanalysis and laccase-based biosensor on the determination of phenolic content and antioxidant power of honey samples

Honey is a functional food widely consumed. Thus, the evaluation of honey samples to determine its phenolic content and antioxidant capacity (AOC) is relevant to determine its quality. Usually AOC is performed by spectrophotometric methods, which lacks reproducibility and practicality. In this context, the electroanalytical methods offer higher simplicity and accuracy. Hence, the aim of this work was to use of electroanalytical tools and laccase based biosensor on the evaluation of AOC and total phenol content (TPC) of honey samples from different countries. The antioxidant power established by electrochemical index presented good correlation with the spectrophotometric FRAP (Ferric Reducing Ability of Plasma) and DPPH (2,2-Diphenyl-1-Picrylhydrazyl) radical scavenging assays. Also, TPC results obtained by the biosensor agreed with the Folin-Ciocalteu (FC) assay. In addition to the semi quantitative results, the electroanalysis offered qualitative parameters, which were useful to indicate the nature of major phenolic compounds.

Efficient Enzyme-Free Biomimetic Sensors for Natural Phenol Detection.

The development of sensors and biosensors based on copper enzymes and/or copper oxides for phenol sensing is disclosed in this work. The electrochemical properties were studied by cyclic and differential pulse voltammetry using standard solutions of potassium ferrocyanide, phosphate/acetate buffers and representative natural phenols in a wide pH range (3.0 to 9.0). Among the natural phenols herein investigated, the highest sensitivity was observed for rutin, a powerful antioxidant widespread in functional foods and ubiquitous in the plant kingdom. The calibration curve for rutin performed at optimum pH (7.0) was linear in a broad concentration range, 1 to 120 µM (r = 0.99), showing detection limits of 0.4 µM. The optimized biomimetic sensor was also applied in total phenol determination in natural samples, exhibiting higher stability and sensitivity as well as distinct selectivity for antioxidant compounds.

Nanostructured TiO2 Carbon Paste Based Sensor for Determination of Methyldopa

Methyldopa is a catecholamine widely used in the treatment of mild to moderate hypertension whose determination in pharmaceutical formulae is of upmost importance for dose precision. Henceforth, a low-cost carbon paste electrode (CPE) consisting of graphite powder obtained from a crushed pencil stick was herein modified with nanostructured TiO2 (TiO2@CPE) aiming for the detection of methyldopa in pharmaceutical samples. The TiO2-modified graphite powder was characterized by scanning electron microscopy and X-ray diffraction, which demonstrated the oxide nanostructured morphology. Results evidenced that sensitivity was nonetheless increased due to electro-catalytic effects promoted by metal modification, and linear response obtained by differential pulse voltammetry for the determination of methyldopa (pH = 5.0) was between 10–180 μmol/L (Limit of Detection = 1 μmol/L) with the TiO2@CPE sensor. Furthermore, the constructed sensor was successfully applied in the detection of methyldopa in pharmaceutical formulations and excipients promoted no interference, that indicates that the sensor herein developed is a cheap, reliable, and useful strategy to detect methyldopa in pharmaceutical samples, and may also be applicable in determinations of similar compounds.

Electrochemical remediation of amoxicillin: detoxification and reduction of antimicrobial activity

Amoxicillin (AMX) is one of the most commonly prescribed antibiotics around the world to treat and prevent several diseases in both human and veterinary medicine. Incomplete removal of AMX during wastewater treatment contributes to its presence in water bodies and drinking water. AMX is an emerging contaminant since its impact on the environment and human health remains uncertain. This contribution was aimed to evaluate the electrochemical oxidation (EO) of AMX using different anodes in tap water, NaCl or Na2SO4 solutions and to evaluate the potential toxicity of remaining AMX and its by-products on zebrafish early-life stages. Chemical intermediates generated after EO were determined by mass spectrometry and their resulting antimicrobial activity was evaluated. AMX did not induce significant mortality in zebrafish during extended exposure but affected zebrafish development (increased body length) from 6.25u202fmg/L to 25u202fmg/L and inhibited enzymatic biomarkers. Carbon modified with titanium oxide (TiO2@C) anode achieved complete AMX removal in just a few minutes and efficiency of the supported electrolytes occurred in the following order: 0.1u202fM NaClu202f>u202f0.1u202fM Na2SO4u202f>u202f0.01u202fM NaClu202f>u202ftap water. The order of potential toxicity to zebrafish early life-stages related to lethal and sublethal effects was as follows: 0.1u202fM Na2SO4 > 0.1u202fM NaCl >0.01u202fM NaClu202f=u202ftap water. Additionally, the EO of AMX using TiO2@C electrode with 0.01u202fM NaCl was able to inhibit the antimicrobial activity of AMX, reducing the possibility of developing bacterial resistance.

Development of a Polyphenol Oxidase Biosensor from Jenipapo Fruit Extract (Genipa americana L.) and Determination of Phenolic Compounds in Textile Industrial Effluents

In this work, an innovative polyphenol oxidase biosensor was developed from Jenipapo (Genipa americana L.) fruit and used to assess phenolic compounds in industrial effluent samples obtained from a textile industry located in Jaraguá-GO, Brasil. The biosensor was prepared and optimized according to: the proportion of crude vegetal extract, pH and overall voltammetric parameters for differential pulse voltammetry. The calibration curve presented a linear interval from 10 to 310 µM (r2 = 0.9982) and a limit of detection of 7 µM. Biosensor stability was evaluated throughout 15 days, and it exhibited 88.22% of the initial response. The amount of catechol standard recovered post analysis varied between 87.50% and 96.00%. Moreover, the biosensor was able to detect phenolic compounds in a real sample, and the results were in accordance with standard spectrophotometric assays. Therefore, the innovatively-designed biosensor hereby proposed is a promising tool for phenolic compound detection and quantification when environmental contaminants are concerned.

Bio-electro oxidation of indigo carmine by using microporous activated carbon fiber felt as anode and bioreactor support

The bioremediation and electro-oxidation (EO) processes are included among the most promising cleaning and decontamination mechanisms of water. The efficiency of bioremediation is dictated by the biological actuator for a specific substrate, its suitable immobilization and all involved biochemical concepts. The EO performance is defined by the anode efficiency to perform the complete mineralization of target compounds and is highlighted by the low or null use of reagent. Recently, the combination of both technologies has been proposed. Thus, the development of high efficient, low cost and eco-friendly anodes for sustainable EO, as well as, supporting devices for immobilization of biological systems applied in bioremediation is an open field of research. Therefore, the aim of this work was to promote the bio-electrochemical remediation of indigo carmine dye (widely common in textile industry), using new anode based on a microporous activated carbon fiber felt (ACFF) and ACFF with immobilized Laccase (Lcc) from Pycnoporus sanguineus. The results were discolorations of 62.7% with ACFF anode and 83.60% with ACFF-MANAE-Lcc anode, both for 60xa0min in tap water. This remediation rates show that this new anode has low cost and efficiency in the degradation of indigo dye and can be applied for other organic pollutant.

Análise evolutiva de processo erosivo acelerado em uma área urbana da cidade de Goiânia

No contexto atual o crescimento das cidades, a deficiencia no planejamento e as caracteristicas das precipitacoes, principalmente em grandes centros urbanos, influenciam nos processos erosivos. Dessa forma, este trabalho propoe a verificacao da origem e evolucao de uma vocoroca localizada no municipio de Goiânia-GO. Realizou-se uma analise temporal no periodo de 2002 a 2014 utilizando imagens de satelite de Google-Earth e ortofotograficas. As imagens foram editadas e geoprocessadas utilizando o programa computacional ArcGis. Verificou-se que os principais fatores para a formacao e evolucao da erosao foram a naturaliza do solo e o inadequado tracado do sistema viario e do planejamento local.