Determinação quimiluminescente de ferro em óleos baseado em pontos quânticos de CdTe usando um sistema fluxo-batelada com extração em fase única e imagens digitais

• Autor(a) principal: Lima, Marcelo Batista de
• Data de Publicação: 2014
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UFPB
• Texto Completo: https://repositorio.ufpb.br/jspui/handle/tede/7130
• topic: Pontos quânticos; Quimiluminescência; Imagens digitais; Matrizes viscosas; Análise em fluxo-batelada; Quantum dots; Chemiluminescence; Digital images; Viscous matrices; Flow-batch analysis; CIENCIAS EXATAS E DA TERRA::QUIMICA

In this work, a novel chemiluminescence method using flow-batch analysis for the determination of iron in viscous samples (edible oil, lubricating oil and biodiesel) employing cadmium telluride quantum dots (CdTe QDs) with detection by digital images from webcam was developed. The analytical method proposed a novel strategy includes a pretreatment of the sample that constitutes on-line availability of total iron by acid extraction in one step. In the automatic pre-treatment, a new strategy was developed for chemiluminescent emission, whereby the available analyte was oxidized to Fe(III) in the presence of dichromate ions and reduced to Fe(II) by direct oxidation of CdTe QDs, allowing promote chemiluminescent emission of these nanocrystals. The influence of the size and concentration QDs in this system was estimated revealing a higher sensitivity and selectivity for the small crystals obtained (1.65 nm). Concerning the flow-batch analysis a new mixing chamber was developed in polytetrafluoroethylene (PTFE) provided with quartz windows in order to allow luminescent probes online. A novel management program the automatic system was developed enabling rapid acquisition and efficient handling of digital images without the need to use another program to tratamendo the information obtained. For the construction of the analytical curve-based mathematical model in the RGB color values was used, therefore, considered the norm of vectors in response. The limit of detection and relative standard deviation were calculated to be 0.66 μg mL 1 and < 1.5 % (n = 3), respectively. The analysis of interfering was successful for the major ions present in solution, revealing significant percentage interference (≤ 5 %). The precision of the method was evaluated by recovery test (97.5 to 103.3 %). The robustness of the method was evaluated by intra- and inter- day comparison of the results obtained and using the reference method with detection by atomic absorption graphite furnace at a 95% level of statistical confidence. Finally, the system showed quite satisfactory analytical frequency (43 h 1) and considerably reducing the consumption of chemicals. Thus, it is demonstrated appreciably the viability of new chemiluminescent method, thus allowing the development of new analytical strategies employing potentially useful quantum dots, automation and digital images.