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Desenvolvimento de analisadores automáticos em fluxo para o monitoramento de analitos de interesse farmacêutico utilizando microdispositivo LTCC e um minifotômetro Labmade
(Universidade Federal de São Carlos, 2011-07-14) Pessoa Neto, Osmundo Dantas; Faria, Ronaldo Censi; https://lattes.cnpq.br/8659496864305621; https://lattes.cnpq.br/6925274393590079
The objective of this study was to develop automatic flow analyzers for the determination of pharmaceutical analytes using a micro-device based on LTCC (Low Temperature Co-fired Ceramics) and a mini-photometer as the detection system. To perform this task, the following devices were developed: 1) A mini-photometer based on RGB-LED (Red Green Blue- Light Emitting Diode) which wavelengths of maximum emission are 465, 525, and 640 nm, respectively, was used as the radiation source. A photodiode (PD) was used as a detector; 2) An optical cell for flowing analysis. A software was developed in graphic language using LabView® 7.0 in order to control and acquire analytical data. The mini-photometer for flowing analysis and software were developed for the determination of N-acetylcysteine (NAC), captopril (CAP), adrenaline (DNA), dopamine (DPN) and ascorbic acid (AAc) in pharmaceutical formulations. First, the mini-photometer was developed and used as a photometric detector. Then, a labmade valve actuator (VA) connected to a computer interface for data acquisition (National Instruments USB 6008) was used to switch on/off the solenoid valves. This interface also enabled to control the mini-photometer as well as the acquisition and processing of transient signals generated in the LTCC. In all determinations, the miniphotometer, the LTCC and the flow system with multicommutation employing threeway solenoid valves were used, except for NAC and CAP where an analyzer with manual injector was used. Solid-phase reactors were also used due to lower reagents consumption. The results from the developed system were compared with reference and validated methods (found in the literature) and there were no significant differences at 95% confidence level. The developed system with LTCC employs low volume of reagents and samples and can be used to determine several analytes in different matrices. applied in any other used (due to), along with a system of universal (able to be applied in any other application in flow) were other good features of this developed system. The good stability and sensibility of the developed mini-photometer (4 x 4 cm) enabled an adequate performance during the determinations.
Avaliação da correlação entre o trabalho essencial de fratura (EWF) e o grau de gelificação de compostos de PVC rígido
(Universidade Federal de São Carlos, 2011-07-14) Laurini, Rafael Vilela; Hage Júnior, Elias; https://lattes.cnpq.br/1240692926327687; https://lattes.cnpq.br/7475072167427838
Poly(vinyl chloride) or PVC is among the most consumed thermoplastics in the world and has great versatility: A wide range of products, from pipes and rigid window frames to flexible foams, various types of materials such as synthetic leather clothing and flexible sheet can be made from PVC. The mechanical performance of the final product of PVC has direct relationship with the severity of the processing conditions, which can be quantified by the gelation level. This work studied the correlation between the gelation level of rigid PVC samples and the specific essential work of fracture (we), obtained by techniques of analysis of the essential work of fracture (EWF). For this assessment, and in order to control the gelation level, PVC compounds were processed in a torque rheometer, and then molded by compression. Different processing temperatures and two dosage levels in the mixture chamber were used to obtain samples with gelation levels between 2% and 74%, assessed by differential scanning calorimetry (DSC). EWF results showed that in PVC samples with low gelation level occur predominantly brittle fracture, while the progressively increasing of gelation level leads to an increasing of ductile portion in the fracture mechanism of the samples. However, samples with excessively high or excessively low gelation levels showed lower we values, when compared to samples with intermediate gelation levels, supported by both industry experiences and results from other researchers, when other techniques were used.