title: Use of temperature dependent Raman spectra to improve accuracy for analysis of complex oil-based samples: lube base oils and adulterated olive oils.
abstract: A simple and effective strategy to improve accuracy for Raman spectroscopic analysis of complex mixture samples by probing a measurement temperature yielding enhanced spectral selectivity has been demonstrated. For the evaluation, the determination of Kinematic Viscosity at 40 °C (KV@40) of lube base oil (LBO) samples was initially attempted. Partial least squares (PLS) was used to determine the KV@40 using Raman spectra of the samples collected at 8 different temperatures from 20 to 90 °C with 10 °C increments. Interestingly, the distinct temperature-induced spectral variation among the samples occurred at 50 °C, thereby resulting in the improved accuracy for determination of KV@40. Two-dimensional (2D) correlation analysis was also performed to find an additional supportive rationale for the improved accuracy. The strategy was further evaluated for the identification of soybean oil-adulterated olive oils using linear discriminant analysis (LDA). Similarly, the discrimination accuracy was improved around 80-90 °C due to the enhanced spectral selectivity between olive and soybean oils. In overall, these two results successfully demonstrate analytical effectiveness of the strategy.
authors.affiliation: Department of Chemistry and Research Institute for Natural Sciences, Hanyang University, Seoul 133-791, Republic of Korea.
authors.forename: Mooeung
authors.initials: M
authors.lastname: Kim
authors.forename: Sanguk
authors.initials: S
authors.lastname: Lee
authors.forename: Kyeol
authors.initials: K
authors.lastname: Chang
authors.forename: Hoeil
authors.initials: H
authors.lastname: Chung
authors.forename: Young Mee
authors.initials: YM
authors.lastname: Jung
mesh_terms: D005506:Food Contamination / Q000032:analysis; D005648:Fuel Oils / Q000032:analysis; D000069463:Olive Oil; D010938:Plant Oils / Q000032:analysis / Q000737:chemistry*; D013024:Soybean Oil / Q000032:analysis; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature
chemical_list: D005648:Fuel Oils; D000069463:Olive Oil; D010938:Plant Oils; D013024:Soybean Oil