Examinando por Materia "Spectrophotometry"

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Acceso abierto
Cuantificación de los componentes bioactivos de mermelada de lima (Citrus limetta Risso) y aguaymanto (Physalis peruviana L.) enriquecida con camu camu (Myrciaria dubia H.B.K. Mc Vaugh) y con características organolépticas aceptables
(Universidad Privada Norbert Wiener, 2018-09-15) Ayala Vilchez, Annika Ada; Guadalupe Sifuentes de Posadas, Luz Fabiola
In the present research, the bioactive components of lime, goldenberry, and camu camu fruits were studied and compared with mixtures of jams. Objectives: To quantify the bioactive components and to determine the level of acceptability of lime and goldenberry jams enriched with camu camu. Methodology: The design is descriptive, cross-sectional, with a quantitative approach to measure the concentrations of vitamin C, phenolic compounds, and the degree of liking or disliking of the jam mixtures. Results: The vitamin C content in jam increased up to 265% compared to the results of fresh fruit. The phenolic content in jam decreased up to 68%. The highest percentage of approval among the three jams was 62.5% of mentions indicating moderate liking for the AG+CC mixture, 67.5% of mentions indicating the same for L+CC, and 71% indicating moderate liking for the L+AG+CC mixture. Conclusions: Vitamin C is found in higher concentration in jam due to the mixture of fruits with high ascorbic acid content. On the other hand, the phenolic content decreased compared to fresh fruit. Overall liking indicates that up to 71% of mentions moderately liked the mixtures of the three jams.
Acceso abierto
Determinación de etanol en sangre en individuos examinados por dos métodos analíticos en el laboratorio central de la Dirección de Criminalística de la Policía Nacional del Perú. Lima 2023
(Universidad Privada Norbert Wiener, 2024-02-27) Puchoc Quispe, Sayuri Yasumi; Vega Salazar, Antony; Ramos Jaco, Antonio Guillermo
The objective of this study was to validate the methods for blood alcohol analysis using GC-FID and UV-VIS and to determine the differences between ethanol concentrations in blood samples from individuals tested at the Central Laboratory of DIRCRI-PNP. The methodology employed was the hypothetical-inductive method, with a quantitative approach, basic and descriptive, longitudinal, and of comparative level. The performance characteristics evaluated in the validation were: selectivity, sensitivity, linearity, accuracy, precision, and robustness, using blood samples with ethanol. For the determination of ethanol in individuals, 240 biological blood samples from the Toxicology Service – DIRCRI-PNP Sampling were processed and analyzed using the GC-FID and UV-VIS methods. Data processing for validation was performed using ANOVA, linear regression, F-test, and Student's t-test applied to the mentioned methods. The performance characteristics of the GC-FID and UV-VIS methods were: detection limits of 0.00191 g/L and 0.0123 g/L; quantification limits of 0.00636 g/L and 0.0411 g/L; accuracy as % recovery of 96.59–100.16% and 86.17–101.16%; repeatability as coefficient of variation of 2.01% and 26.47%; intermediate precision as coefficient of variation of 1.88% and 22.11%. Conclusion: The GC-FID method cannot be interchangeable or replaceable by UV-VIS due to the high variability in the performance characteristics of the methods.
Acceso abierto
Determinación de plomo, cadmio y manganeso en sedimentos de hojas de Sauce "Salix alba" en las avenidas Abancay y Tacna, Lima – Noviembre 2014–enero 2015
(Universidad Privada Norbert Wiener, 2015) Cajas Regal, Diana Rebeca; Evangelista Doria, Luisa Celina; Churango Valdez, Javier
The concentration of lead, cadmium, and manganese was determined in leaf sediments of Salix alba (willow) collected from Tacna and Abancay avenues between November 2014 and January 2015. A total of 86 samples were analyzed, 44 from Abancay Avenue and 42 from Tacna Avenue, using flame atomic absorption spectrophotometry. The results for lead and cadmium were compared with the Environmental Quality Standards for soils (ECAS 2013) in Peru and with U.S. EPA standards (USEPA 2002). Manganese levels were compared with the reference values of the Agency for Toxic Substances and Disease Registry (ATSDR 2012). Findings showed that 95% of samples from Abancay Avenue and 100% from Tacna Avenue exceeded the Peruvian permissible limits for lead in residential/park soils. For cadmium, 100% of Abancay samples were above the standard. Compared with U.S. EPA human health risk levels, 18% of Abancay and 10% of Tacna samples exceeded the limits. No manganese sample surpassed the values established by ATSDR. It is therefore recommended to continue urban tree-cleaning programs, as they help reduce environmental contamination by heavy metals.
Acceso abierto
Evaluación de la translucidez según espesor de dos resinas compuestas, nanohibrida y nanoparticulada, en un estudio in vitro
(Universidad Privada Norbert Wiener, 2026-05-21) Gonzalo Apaza, Gaby Edith; Vílchez Bellido, Dina
El propósito de este estudio fue evaluar la translucidez según el espesor de dos resinas compuestas, nanohíbrida y nanoparticulada, en un estudio in vitro. Se desarrolló bajo un método hipotético deductivo, aplicado, cuantitativo y un diseño experimental in vitro, comparativo y transversal. La muestral estuvo conformada por discos de ambas resinas en tres espesores (1,5 mm; 1,0 mm y 0,5 mm), evaluándose el parámetro de translucidez (TP) mediante espectrofotometría. El análisis estadístico se realizó, aplicando pruebas no paramétricas debido a la no normalidad de los datos (p < 0,05 según Shapiro–Wilk). La prueba de Kruskal–Wallis mostró diferencias significativas en la translucidez según el espesor para la resina nanohíbrida (p < 0,001) y la nanoparticulada (p < 0,001), evidenciando que el aumento del espesor reduce la translucidez. En cambio, la prueba de Mann–Whitney (p = 0,812) indicó que no existen diferencias significativas entre ambas resinas al comparar sus valores promedio de translucidez. En conclusión, la disminución de la traslucidez se da en medida que incrementa el espesor de las resinas compuestas, siendo este el principal factor que determina su comportamiento óptico. Asimismo, no se hallaron diferencias significativas entre las resinas nanohíbrida y nanoparticulada, lo que sugiere propiedades ópticas equivalentes bajo las condiciones evaluadas. Estos resultados contribuyen a una selección más precisa de materiales restauradores en función de su desempeño estético.
Acceso abierto
Identificación y cuantificación del colorante artificial azoico tartrazina en alimentos de consumo masivo de loncheras escolares en el distrito de San Juan de Lurigancho. Lima. 2018
(Universidad Privada Norbert Wiener, 2022-06-01) Aguirre Ñiquen, Diego Orlando; Diestra López, Elizabeth Esther; Ramos Jaco, Antonio Guillermo
The present thesis, entitled Identification and Quantification of the Artificial Azo Dye Tartrazine in Mass-Consumption Foods from School Lunchboxes in the District of San Juan de Lurigancho, Lima, 2018, addressed the real problem generated by the consumption and overuse of products containing tartrazine and its implications for children’s health. Objective: To identify and quantify the artificial azo dye tartrazine in mass-consumption foods from school lunchboxes in San Juan de Lurigancho, Lima, 2018. Methodology: This was a quantitative, descriptive, cross-sectional study applied to school lunchbox foods, using the Arata Possetto method and UV-Visible spectrophotometry. Results and Conclusions: The presence of azo groups (tartrazine) was confirmed in all samples through the identification test. Quantification also revealed azo groups (tartrazine) at the following concentrations: nectars (Frugos del Valle) 810.335 mg/kg, cereal flakes (Zuck) 794.959 mg/kg, orange-flavored sponge cakes (Bimbo) 779.83 mg/kg, orange-flavored cookies (Tentación) 769.609 mg/kg, and peach-flavored yogurt (Laive) 770.392 mg/kg. All products exceeded the permissible limits established by the Codex Alimentarius (<500 ppm) and Indecopi (<450 ppm).