Lubricating oils are crucial in the operation of automotive engines because they both reduce friction between moving parts and protect against corrosion. However, the performance of lubricant oil may be affected by contaminants, such as gasoline, diesel, ethanol, water and ethylene glycol. Although there are many standard methods and studies related to the quantification of contaminants in lubricant oil, such as gasoline and diesel oil, to the best of our knowledge, no methods have been reported for the quantification of ethanol in used Otto cycle engine lubrication oils. Therefore, this work aimed at the development and validation of a routine method based on partial least-squares multivariate analysis combined with attenuated total reflectance in the mid-infrared region to quantify ethanol content in used lubrication oil. The method was validated based on its figures of merit (using the net analyte signal) as follows: limit of detection (0.049%), limit of quantification (0.16%), accuracy (root mean square error of prediction=0.089% w/w), repeatability (0.05% w/w), fit (R(2)=0.9997), mean selectivity (0.047), sensitivity (0.011), inverse analytical sensitivity (0.016% w/w(-1)) and signal-to-noise ratio (max: 812.4 and min: 200.9). The results show that the proposed method can be routinely implemented for the quality control of lubricant oils.
Ao professor Dr. Younés Messaddeq por ter aceito orientar-me junto ao Instituto de Física de São Carlos, sem ao menos me conhecer, a não ser como aluno de graduação. Foi com o professor Younes que tive as primeiras noções do que são fibras ópticas, amplificadores ópticos, de como ser obtém a preforma e outras coisas mais e por confiar em mim. Aos professores Doutores Antônio Carlos Hernandes (USP-SC) e Carlos Suzuki (UNICAMP) por aceitarem fazer parte da banca e pelas sugestões de melhoriia ao trabalho. Ao professor Dr. Ricardo Benetton Martins por me co-orientar na Fundação CPqD, por tomar possível desenvolver este trabalho no CPqD, pela discussão de alguns resultados, e por se mostrar sempre solícito quando eu precisei e por me ensinar a ser prático. E também pela amizade, pelas conversas incentivo. À Érica Regina de Favari Signini técnica administrativa da seção de Pós Graduação da Interunidades por sua competência e por mostrar sempre solícita. E a CAPES pela apoio financeiro a mim concedido para a realização deste trabalho.
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