An Automated Method for Chemical Composition Analysis of Lubricant Base Oils by Using Atmospheric Pressure Chemical Ionization Mass Spectrometry
Since its invention in the 1950s, field ionization mass spectrometry (FI MS) has been, and currently is, the go-to technique employed by the petrochemical industry for the identification of the different types of nonvolatile compounds in their products. Unfortunately, FI MS has several inherent drawbacks, such as poor reproducibility. The performance of positive-ion mode atmospheric pressure chemical ionization mass spectrometry (APCI MS) with O2 gas as the sheath/auxiliary gas and a saturated hydrocarbon solvent/reagent was recently compared with that of FI MS and found to show promise as an alternative, highly reproducible method for lubricant base oil analysis. We report here on the automation of the APCI/O2/saturated hydrocarbon MS method. Isooctane was chosen as the optimal APCI solvent/reagent for base oil ionization due to the low level of fragmentation it provided for model compound mixtures. Three minutes was determined to be the shortest possible cleaning time between samples, regardless of the base oil viscosity. The total analysis time for each sample was 5 min. The reproducibility of the method was assessed by determining within-day and between-day precisions and total precision for hydrocarbon class distributions measured for three different base oils. All total precision values were found to be better than 6.2%, suggesting that the automated (+)APCI/O2/isooctane method is reproducible and robust.
KeywordsBase oils APCI Linear quadrupole ion trap Automated Hydrocarbons Carbenium ions
The authors gratefully acknowledge Neste for financial support for this project. We also thank Dr. Chunfen Jin for her mentorship and inspiration. We also would like to thank Tiina Laaksonen from Neste for her guidance throughout the project.
- 2.Duan, P., Qian, K., Habicht, S.C., Pinkston, D.S., Fu, M., Kenttämaa, H.I.: Analysis of base oil fractions by ClMn(H2O)+ chemical ionization combined with laser-induced acoustic desorption/Fourier transform ion cyclotron resonance mass spectrometry. Anal. Chem. 80(6), 1847–1853 (2008)CrossRefGoogle Scholar
- 3.Kramer, D.C.; Ziemer, J.N.; Cheng, M.T.; Fry, C.E.; Reynolds, R.N.; Lok, B.K.; Sztenderowicz, M.L.; Krug, R.R. Influence of group II & III base oil composition on VI and oxidation stability. NLGI Spokesman. 1-36 (1999)Google Scholar
- 5.Sastry, M.I.S., Chopra, A., Sarpal, A.S., Jain, S.K., Srivastava, S.P., Bhatnagar, A.K.: Determination of physicochemical properties and carbon-type analysis of base oils using mid-IR spectroscopy and partial least-squares regression analysis. Energy Fuel. 12(2), 304–311 (1998)CrossRefGoogle Scholar
- 9.Jin, C., Viidanoja, J., Li, M., Zhang, Y., Ikonen, E., Root, A., Romanczyk, M., Manheim, J., Dziekonski, E., Kenttämaa, H.I.: Comparison of atmospheric pressure chemical ionization and field ionization mass spectrometry for the analysis of large saturated hydrocarbons. Anal. Chem. 88(21), 10592–10598 (2016)CrossRefGoogle Scholar
- 14.Owen, B.C., Gao, J., Borton, D.J., Amundson, L.M., Archibold, E.F., Tan, X., Azyat, K., Tykwinski, R., Gray, M., Kenttämaa, H.I.: Carbon disulfide reagent allows the characterization of nonpolar analytes by atmospheric pressure chemical ionization mass spectrometry. Rapid Commun. Mass Spectrom. 25(14), 1924–1928 (2011)CrossRefGoogle Scholar
- 15.The Encyclopedia of Mass Spectrometry, 1st Ed.; Gross, M. L., Caprioli, R. M., Eds.; Elsevier: Amsterdam; Boston, (2003)Google Scholar
- 18.Frash, M.V., Solkan, V.N., Kazansky, V.B.: A quantum-chemical study of hydride transfer from alkanes to carbenium cations in the gas phase: a comparison with liquid- and solid-acid catalytic systems. J. Chem. Soc. Farad. T. 93(4), 512–520 (1997)Google Scholar
- 19.Lias, S.G., Eyler, J.R., Ausloos, P.: Hydride transfer reactions involving saturated hydrocarbons and CCl3 +, CCl2H+, CCl2F+, CF2Cl+, CF2H+, CF3 +, NO+, C2H5 +, sec-C3H7 + and t-C4H9 +. Int. J. Mass Spectrom. 19, 219–239 (1976)Google Scholar