title: Development and validation of an environmentally friendly attenuated total reflectance in the mid-infrared region method for the determination of ethanol content in used engine lubrication oil.
abstract: 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.
authors.affiliation: UNESP-São Paulo State University, Institute of Chemistry, Center for Monitoring and Research of the Quality of Fuels, Biofuels, Crude Oil and Derivatives-CEMPEQC, Araraquara, SP, Brazil. rrhatanaka@gmail.com
authors.forename: Rafael Rodrigues
authors.initials: RR
authors.lastname: Hatanaka
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Sequinel
authors.forename: Carlos Eduardo
authors.initials: CE
authors.lastname: Gualtieri
authors.forename: Antônio Carlos Bergamaschi
authors.initials: AC
authors.lastname: Tercini
authors.forename: Danilo Luiz
authors.initials: DL
authors.lastname: Flumignan
authors.forename: José Eduardo
authors.initials: JE
authors.lastname: de Oliveira
mesh_terms: D001336:Automobiles; D002849:Chromatography, Gas; D000431:Ethanol / Q000032:analysis*; D016018:Least-Squares Analysis; D057230:Limit of Detection; D059625:Liquid-Liquid Extraction; D054327:Lubricants / Q000032:analysis* / Q000592:standards; D008899:Mineral Oil / Q000032:analysis* / Q000592:standards; D015999:Multivariate Analysis; D015203:Reproducibility of Results; D014867:Water / Q000032:analysis
chemical_list: D054327:Lubricants; D014867:Water; D000431:Ethanol; D008899:Mineral Oil