title: Automated acid and base number determination of mineral-based lubricants by fourier transform infrared spectroscopy: commercial laboratory evaluation.
abstract: The Fluid Life Corporation assessed and implemented Fourier transform infrared spectroscopy (FTIR)-based methods using American Society for Testing and Materials (ASTM)-like stoichiometric reactions for determination of acid and base number for in-service mineral-based oils. The basic protocols, quality control procedures, calibration, validation, and performance of these new quantitative methods are assessed. ASTM correspondence is attained using a mixed-mode calibration, using primary reference standards to anchor the calibration, supplemented by representative sample lubricants analyzed by ASTM procedures. A partial least squares calibration is devised by combining primary acid/base reference standards and representative samples, focusing on the main spectral stoichiometric response with chemometrics assisting in accounting for matrix variability. FTIR(AN/BN) methodology is precise, accurate, and free of most interference that affects ASTM D664 and D4739 results. Extensive side-by-side operational runs produced normally distributed differences with mean differences close to zero and standard deviations of 0.18 and 0.26 mg KOH/g, respectively. Statistically, the FTIR methods are a direct match to the ASTM methods, with superior performance in terms of analytical throughput, preparation time, and solvent use. FTIR(AN/BN) analysis is a viable, significant advance for in-service lubricant analysis, providing an economic means of trending samples instead of tedious and expensive conventional ASTM(AN/BN) procedures.
authors.affiliation: Fluid Life Corporation, Edmonton, AB, Canada.
authors.forename: Craig
authors.initials: C
authors.lastname: Winterfield
authors.affiliation: McGill University, Montreal, QC, Canada frederik.vandevoort@mcgill.ca.
authors.forename: F R
authors.initials: FR
authors.lastname: van de Voort
mesh_terms: D000143:Acids / Q000032:analysis*; D000468:Alkalies / Q000032:analysis*; D007753:Laboratories; D054327:Lubricants / Q000737:chemistry*; D008422:Materials Testing / Q000379:methods*; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods* / Q000592:standards
chemical_list: D000143:Acids; D000468:Alkalies; D054327:Lubricants
keywords: ASTM; D2896; D4739; D664; FTIRAN; FTIRBN; Fourier transform infrared spectroscopy; ISO; condition monitoring; equipment reliability; lubricant analysis; lubricant quality; lubricant trending; mineral oil analysis; total acid number (TAN); total base number (TBN)