Characterization of engine lubricants by fluorescence spectroscopy and chemometrics

William Mbogning Feudjio; Gilbert Yvon Mbesse Kongbonga; Sagesse Bel Christ Kogniwali-Gredibert; Hassen Ghalila; Pale Wang-Yang; Youssef Majdi; Cyril Kenfack Assongo; Mama Nsangou

doi:10.1016/j.saa.2021.119539

Characterization of engine lubricants by fluorescence spectroscopy and chemometrics

Spectrochim Acta A Mol Biomol Spectrosc. 2021 May 5:252:119539. doi: 10.1016/j.saa.2021.119539. Epub 2021 Feb 4.

Authors

William Mbogning Feudjio¹, Gilbert Yvon Mbesse Kongbonga², Sagesse Bel Christ Kogniwali-Gredibert³, Hassen Ghalila⁴, Pale Wang-Yang³, Youssef Majdi⁴, Cyril Kenfack Assongo³, Mama Nsangou⁵

Affiliations

¹ Laboratory of Optics and Applications, Centre for Atomic Molecular Physics and Quantum Optics (CEPAMOQ), Faculty of Science, The University of Douala, P.O. Box 8580, Douala, Cameroon. Electronic address: mbogningfeudjio@gmail.com.
² Department of Physics, Faculty of Science, The University of Bangui, P.O. Box 908, Bangui, Central African Republic. Electronic address: yvonmbesse@yahoo.fr.
³ Laboratory of Optics and Applications, Centre for Atomic Molecular Physics and Quantum Optics (CEPAMOQ), Faculty of Science, The University of Douala, P.O. Box 8580, Douala, Cameroon.
⁴ Laboratoire de Spectroscopie Atomique Moléculaire et Applications (LSAMA), Faculty of Science, The University of Tunis El Manar, P.O. Box 2092, Tunis, Tunisia.
⁵ Department of Physics, Higher Teacher Training School, The University of Maroua, P.O. Box 46, Maroua, Cameroon.

PMID: 33588363
DOI: 10.1016/j.saa.2021.119539

Abstract

In this study, principal component analysis (PCA) and parallel factor analysis (PARAFAC) combined with excitation-emission matrix fluorescence (EEMF) were used to determine the most efficient excitation wavelengths of engine lubricants; identify their fluorophores; classify them and look for correlations between their fluorescence and their physical parameters. EEMF spectra were obtained for the different samples in the range of 260 to 600 nm, and 300 to 700 nm for excitation and emission wavelengths respectively. PCA and PARAFAC showed that the efficient excitation wavelengths for engine lubricants are 300, 350, 400, 450 and 470 nm. These five wavelengths represented the maxima of the PARAFAC recovered excitation profiles, of which two were attributed to fluorene and pyrene. The relative proportions of the PARAFAC retrieved components were used to classify engine lubricants with a satisfactory percentage of classification of 70%. Finally, a good correlation was obtained between some physical parameters (particularly the viscosity) of engine lubricants and their fluorescence.

Keywords: Chemometrics; Efficient excitation; Engine lubricants; Fluorescence.