Papers by David Romero-Estévez
Anuario de arqueología, Dec 24, 2023
JSFA Reports, Oct 12, 2023
Revista Internacional De Contaminacion Ambiental, Oct 3, 2023
infoANALÍTICA, 2018
En el presente estudio se estableció el porcentaje de biodegradabilidad de muestras de polietilen... more En el presente estudio se estableció el porcentaje de biodegradabilidad de muestras de polietileno de alta densidad (HDPE) con aditivos degradables, mediante condiciones controladas de compostaje aerobio en un período de 90 días, para lo cual se utilizó el CO 2 proveniente de procesos biológicos de microorganismos del suelo, como indicador de biodegradabilidad. Para captar el CO 2 se emplearon soluciones de KOH 0,1 M y 0,5 M. Además se establecieron los parámetros de análisis estipulados en la norma NTE INEN 2040:2012 para seleccionar el inóculo de compostaje. Como control positivo se utilizó celulosa, que alcanzó el 91 % de biodegradabilidad con respecto al valor teórico de CO 2 . Los resultados obtenidos al concluir el período de 90 días, indicaron que la muestra de HDPE con aditivo A1 (HDPE-A1) alcanzó el 75 % de biodegradabilidad por generación de CO 2 , seguido del HDPE-A2 con el 43 % y el HDPE-A3 con el 22 %, con respecto a la celulosa. Los valores demuestran que el aditivo A1...
Toxicology Reports, 2020
Vegetables are one of the most important components in the human diet, but despite their multiple... more Vegetables are one of the most important components in the human diet, but despite their multiple nutritional components, studies have demonstrated the presence of trace metals in their edible parts. In Ecuador, two of the most consumed crops are tomato (Solanum lycopersicum) and lettuce (Lactuca sativa). The importance of these two crops in the Ecuadorian diet, especially in large and touristic locations like the Metropolitan District of Quito, implies food safety-related concerns for locals and visitors. However, no previous studies have quantified the cadmium and lead levels in these two vegetables using samples from Quito markets. Thus, the aim of this study was to determine the cadmium and lead content in both tomato and lettuce products from main nonorganic and organic markets in Quito using a graphite furnace atomic absorption spectrophotometer. The results showed that the cadmium levels were lower than 0.058 in tomatoes and 0.034 mg/kg in lettuce, which are under the respective threshold values (0.100 and 0.200 mg/kg). Regarding lead, levels lower than 0.066 mg/kg were detected in lettuce, which did not exceed the CXS 193-1995 threshold value, while levels in tomatoes were near or exceeded the threshold value (0.100 mg/kg) from four markets (0.209, 0.162, 0.110, 0.099 mg/kg), suggesting a possible risk from tomato consumption. In addition, most vegetables marketed as organic had higher metal content than those coming from nonorganic markets. Based on these results, local health and commercial control authorities should monitor contaminants in food products sold in Quito and other places in Ecuador to ensure their safety.
Antioxidants
This study evaluated the antioxidant properties and chemical composition of the seeds, pulp and p... more This study evaluated the antioxidant properties and chemical composition of the seeds, pulp and peels of Ungurahua (Oenocarpus bataua) and Pasu (Gustavia macarenensis)—fruits, native to the Ecuadorian Amazon. The antioxidant capacity was measured by 1,1-diphenyl-2-picrylhydrazyl (DPPH) and cyclic voltammetry (antioxidant index 50 (AI50)) assays; differential pulse voltammetry was used to evaluate antioxidant power using the electrochemical index. The total phenolic content, as well as the yellow flavonoid and anthocyanin content, were quantified via spectrophotometry. In addition, the trans-resveratrol and ascorbic acid content were evaluated through high performance liquid chromatography (HPLC). Ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) was used to identify secondary metabolites with possible therapeutic properties. Results showed that the Pasu peel and seed extracts had the highest antioxidant capacity, followed by the Ungurahua peel; these results were c...
Journal of Food Composition and Analysis
infoANALÍTICA
Los materiales tradicionales derivados del petróleo como el polietileno y polipropileno son los m... more Los materiales tradicionales derivados del petróleo como el polietileno y polipropileno son los más empleados en el campo de la protésica, sin embargo, la tendencia a la protección del medio ambiente amerita el análisis de nuevos materiales biodegradables y biocompatibles. El ácido poliláctico (PLA) es un polímero obtenido a partir de fuentes naturales, que se usa entre muchas aplicaciones en prótesis ortopédicas por su bajo costo. Con el desarrollo de la nanotecnología, pueden incorporarse nanopartículas de diferente naturaleza con el objetivo de mejorar las propiedades mecánicas del PLA, sin embargo, existe información limitada. En este compendio se describen las propiedades físicas y químicas del PLA, así como las condiciones para su impresión en 3D. Se analizan varios nanomateriales tales como nanocelulosa, nanofibras de quitosano, nanotubos de carbono, grafeno, óxido de titanio, nanopartículas de óxido de hierro, nanopartículas de plata, nanopartículas de sílice mesoporosa, ent...
Journal of Food Composition and Analysis
Abstract Consumers have considered organic crops more beneficial to health and the environment as... more Abstract Consumers have considered organic crops more beneficial to health and the environment as opposed to conventional crops. The following review aims to compare the major nutrients and mineral content in organic and conventional tomatoes. As such, articles related to the comparison of organic and conventional tomato crops were selected, as well as articles in which nutrient and/or mineral content were determined. Four research groups were formed based on their hypotheses. The quality of each study was evaluated considering the statistical tools used to determine the results’ significance. Result ranges were compared to analyze the variation in the individual nutrient and mineral content in each study. No objective evidence was found that organic crops are nutritionally better than conventional crops; in both cases, results were within similar ranges. For conventional and organic tomatoes (fresh weight), the respective concentration ranges were 1.00 to 63.8 mg/100 g and 10.7 to 40.0 mg/100 g for ascorbic acid, 0.02 to 337.0 mg/100 g and 0.44 to 422 mg/100 g for lycopene, and 0.0058 to 4.44 mg/100 g and 0.0061 to 3.90 mg/100 g for β-carotene. For polyphenol and mineral content, the results varied depending on farming technique. Finally, aspects related to environmental protection help organic products achieve better market positioning.
Universitas Scientiarum
Environmental pollution allows heavy metals to interact with ecosystems, bioaccumulating and pass... more Environmental pollution allows heavy metals to interact with ecosystems, bioaccumulating and passing through the food chain. Animals and human scan consume contaminated species and reach toxic and harmful concentrations in their organisms. While there are international regulatory frameworks for heavy metal contents, these are not always known or suitable for local conditions. This situation calls for the development of locally-applicable analytical methods for the determination of heavy metal concentrations in common vegetal and animal food products. Two established methods (AOAC999.11, based on sample drying and calcination, and IPNAC-06-00, based on microwave-assisted acid digestion) were comparatively tested at the CESAQ-PUCE laboratory in Quito, Ecuador, to determine their suitability. Sample matrices used were non industrial, non-organic tomato, lettuce, and beef commonly found in local markets. Heavy metals tested were cadmium, nickel, and lead. Test guidelines and comparative...
Foods
In this study, cadmium (Cd), nickel (Ni), and lead (Pb) contents were analyzed in sixteen banana ... more In this study, cadmium (Cd), nickel (Ni), and lead (Pb) contents were analyzed in sixteen banana composite samples from different commercial establishments from eleven Ecuadorian production provinces using graphite furnace atomic absorption spectrophotometry. The concentrations (fresh weight) in the samples collected (9.3–47.3 μg·kg−1 for Cd, 16.1–105.6 μg·kg−1 for Ni, and 36.9–538.0 μg·kg−1 for Pb) were used to calculate the estimated daily intake (EDI), target hazard quotient (THQ), and target carcinogenic risk (CR) associated with dietary exposure to these potentially toxic metals. Cd and Ni results showed that every sample had EDIs lower than the oral reference dose and THQ values lower than 1, demonstrating that there was no non-carcinogenic risk related to the exposure to Cd and Ni. In the case of Pb, two EDIs results were higher than the reference dose, also their corresponding THQ values were higher than 1. The lead CR in all samples was less than 1 × 10−4, the upper limit u...
Methods and Protocols
In 2017, the World Health Organization and the United Nations Environment Programme formed the Gl... more In 2017, the World Health Organization and the United Nations Environment Programme formed the Global Alliance to Eliminate Lead Paint. All alliance member countries have pledged to develop control regulations that include lead threshold limits. To improve regulations and demonstrate compliance of paint industry products, it is necessary to have adequate, locally applicable methodologies. In this sense, the main objective of this research was to validate the methodology of alkaline extraction for the quantification of lead in ten different types of Ecuadorian commercial paints using flame atomic absorption spectrophotometry. Two hundred and fifty samples from different paint industry products were analyzed, and the results were used to evaluate the method’s performance and robustness. It was determined that the method could be applied for lead concentrations above 100 mg·kg−1, and results showed relative standard deviation values lower than 14.8% and fortification recoveries between...
Frontiers in Environmental Science
Santa Rosa Island community members derive their income and livelihoods from bio-aquatic resource... more Santa Rosa Island community members derive their income and livelihoods from bio-aquatic resources, principally bivalves of the genus Anadara, both for subsistence use and commercial purposes. Bivalve mollusks have a sedentary lifestyle and feed by filtering water, meaning they absorb all surrounding substances, including harmful elements like toxic metals. This study aimed to analyze different-sized samples of Anadara tuberculosa and Anadara similis, sediment, and Rhizophora mangle leaves to determine their total amount of cadmium, lead, and chromium as a first approach to the evaluation of the health risk related to the consumption of bivalves. For both species from four sampling sites, the results revealed metal concentrations in the bivalves between 0.211 and 0.948 mg kg −1 , 0.038, and 0.730 mg kg −1 , and 0.067 and 0.923 mg·kg −1 for Cd, Cr, and Pb, respectively. The calculated potential risk (>1) for cadmium, considering all body weights, showed a high health risk for consumers. In the case of lead, the results showed a high health risk in children. There was no risk found for chromium. For sediments, the mean values were 2.14, 29.99, and 12.37 mg·kg −1 and for the Rhizophora mangle leaves were 2.23, 4.22, and 3.35 mg·kg −1 for Cd, Cr, and Pb, respectively. These results did not show a relation with the metal content in bivalves.
infoANALÍTICA
El presente estudio corresponde a la evaluación de la calidad del agua del río Pita y sus afluent... more El presente estudio corresponde a la evaluación de la calidad del agua del río Pita y sus afluentes ubicados dentro y fuera del Parque Nacional Cotopaxi. Se fijaron siete estaciones de monitoreo, en las cuales se recolectaron muestras aguas arriba y abajo de cada afluente, en abril de 2018 y abril de 2019. Se midieron parámetros físicoquímicos in situ como: pH, temperatura y porcentaje de saturación de oxígeno disuelto (OD); se analizaron los parámetros establecidos en la normativa ambiental ecuatoriana: Texto Unificado de la Legislación Secundaria del Ministerio del Ambiente, TULSMA, Anexo 1, Libro VI, tabla 2, aplicando métodos de análisis de acuerdo al Standard Methods for the Examination of Water and Wastewater (APHA). Los resultados indican que las muestras recolectadas superan el límite permisible para fenoles (0,001 mg·dm-3) establecido en el TULSMA, a excepción del río Hualpaloma, mientras que para el caso de hierro, todas las muestras del cauce del río Pita y sus afluentes ...
Food Control
Heavy metals such as cadmium (Cd) are a global concern; recent researches have concluded that the... more Heavy metals such as cadmium (Cd) are a global concern; recent researches have concluded that they are related to health risks caused by contaminated food intake. Although Cd contents in cocoa beans and their derivatives have been investigated, the relationship of Cd concentration with other metals such as nickel (Ni) and lead (Pb) information is not available. Thus, this study uses a general approach to examine Cd, Ni, and Pb concentrations in cocoa beans from nine Ecuadorian provinces. It aims to determine a possible relationship between each metal content. As results, Ni was the most abundant reaching concentrations between 1.462 and 8.528 mg kg −1 (mean 3.930 mg kg −1), followed by Pb between 0.502 and 1.966 mg kg −1 (mean 1.432 mg kg −1) and Cd between 0.267 and 1.715 mg kg −1 (mean 0.753 mg kg −1). The regression analysis results (< 0.2420746), the Pearson correlation coefficient values (< 0.369) and variation inflation factors results (< 1.319) do not demonstrate linear correlation or multivariate regression between each metal tested, thus it is not necessary to consider competition regarding metal intake by plants to develop successful remediation techniques. Nevertheless, the high values obtained should be considered by public health and commerce authorities for establishing permissible levels of Ni and Pb.
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Papers by David Romero-Estévez