Desenvolvimento de método analítico para determinação do teor de etanol em óleo lubrificante usado proveniente de motores ciclo Otto
Data
2010-12-20
Autores
Hatanaka, Rafael Rodrigues [UNESP]
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ISSN da Revista
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Os óleos lubrificantes exercem papel fundamental no funcionamento dos motores automotivos, pois, além de reduzir o atrito entre as peças, ainda as protegem contra a corrosão. Entretanto, o desempenho do óleo lubrificante pode ser afetado por contaminantes. Embora existam várias normas e trabalhos relacionados a métodos para quantificação de contaminantes em óleo lubrificante, como por exemplo gasolina e óleo diesel, até o alcance de nossos conhecimentos, não há método descrito para quantificação de etanol em óleo lubrificante usado de motores ciclo Otto. Nesse sentido, o presente trabalho teve como objetivo o desenvolvimento e a validação de um método aplicável em rotina para quantificação de etanol em tal óleo lubrificante usado. Para tanto, foram avaliadas as técnicas combinadas: Headspace - Gas Chromatography - Flame Ionization Detector (HS-GC-FID) e Fourier Transform Infra Red Spectroscopy - Total Attenuated Reflectance - Partial Least Squares (FTIR-ATR-PLS), com e sem tratamento prévio das amostras, sendo que os melhores resultados foram obtidos pela técnica FTIR-ATR-PLS, com pré-tratamento por Extração Líquido/líquido (ELL), otimizada por planejamento fatorial. Na sequencia, foram avaliados dois cristais com diferentes ângulos de incidência para obtenção dos espectros por ATR, sendo que o cristal de ZnSe com θ = 45 º mostrou-se mais o mais adequado. Então, a partir dessas melhores condições experimentais, o método foi validado através das figuras de mérito, as quais apresentaram os seguintes resultados: LD (0,049 %), LQ (0,16 %), exatidão (RMSEP = 0,089 % (m/m) de etanol), repetibilidade (0,05 % (m/m) etanol), ajuste (R2 = 0,9997), seletividade média (0,047), sensibilidade (0,011), inverso da sensibilidade analítica (0,016 % (m/m)-1 de etanol), razão sinal ruído (máximo: 812,4 e mínimo: 200,9) e BIAS. Os resultados obtidos mostram...
The lubricating oils have a crucial role in the operation of automotive engines, not only reduce friction between moving parts, but also protect against corrosion. However, the performance of lubricating oil may be affected by contaminants. Although there are many standards methods and studies related to methods for quantification of contaminants in lubricating oil such as gasoline and diesel oil, to the best our knowledge, there are no described methods for quantification of ethanol in Otto cycle engine used lubricating oil. In that sense, this work aimed the development and validation of an applicable in routine and method to quantify ethanol content in this used lubricating oil. For that were evaluated the combined techniques: Headspace/Gas Chromatography/Flame Ionization Detector (HS-GC-FID) and Fourier Transform Infrared Spectroscopy/Attenuated Total Reflectance/Partial Least Squares (PLS-ATR-FTIR) with and without pretreatment of the samples, and the best results were obtained to the FTIR-ATR-PLS with treatment by ELL (which was optimized by factorial design). Then, two crystals of ATR with differents incident angles were studied to obtain the spectra and the ZnSe crystal with θ = 45 ° was more appropriate for analysis. Then, from the best obtained conditions, the method was validated through the figures of merit, which presented the following results: LD (0.049 %), LQ (0.16 %), accuracy (RMSEP = 0.089 % (w/w) ethanol), repeatability (0,05 % (w/w) ethanol), fit (R2 = 0.9997), mean selectivity (0.047), sensitivity (0.011), inverse analytical sensitivity (0.016% (m / m)-1 of ethanol), signal-to-noise ratio (max: 812.4 and min: 200.9) and BIAS. The results show that the method developed and validated can be implemented, in routine, for quality control laboratories of lubricating oils
The lubricating oils have a crucial role in the operation of automotive engines, not only reduce friction between moving parts, but also protect against corrosion. However, the performance of lubricating oil may be affected by contaminants. Although there are many standards methods and studies related to methods for quantification of contaminants in lubricating oil such as gasoline and diesel oil, to the best our knowledge, there are no described methods for quantification of ethanol in Otto cycle engine used lubricating oil. In that sense, this work aimed the development and validation of an applicable in routine and method to quantify ethanol content in this used lubricating oil. For that were evaluated the combined techniques: Headspace/Gas Chromatography/Flame Ionization Detector (HS-GC-FID) and Fourier Transform Infrared Spectroscopy/Attenuated Total Reflectance/Partial Least Squares (PLS-ATR-FTIR) with and without pretreatment of the samples, and the best results were obtained to the FTIR-ATR-PLS with treatment by ELL (which was optimized by factorial design). Then, two crystals of ATR with differents incident angles were studied to obtain the spectra and the ZnSe crystal with θ = 45 ° was more appropriate for analysis. Then, from the best obtained conditions, the method was validated through the figures of merit, which presented the following results: LD (0.049 %), LQ (0.16 %), accuracy (RMSEP = 0.089 % (w/w) ethanol), repeatability (0,05 % (w/w) ethanol), fit (R2 = 0.9997), mean selectivity (0.047), sensitivity (0.011), inverse analytical sensitivity (0.016% (m / m)-1 of ethanol), signal-to-noise ratio (max: 812.4 and min: 200.9) and BIAS. The results show that the method developed and validated can be implemented, in routine, for quality control laboratories of lubricating oils
Descrição
Palavras-chave
Quimica organica, Quimiometria, Chemometrics
Como citar
HATANAKA, Rafael Rodrigues. Desenvolvimento de método analítico para determinação do teor de etanol em óleo lubrificante usado proveniente de motores ciclo Otto. 2010. 91 f. Dissertação (mestrado) - Universidade Estadual Paulista, Instituto de Química de Araraquara, 2010.