Additive analysis in lubricating oil by FD method using JMS-T2000GC AccuTOF™ GC-Alpha [GC-TOFMS Application]

Experiment

Table 1 shows the details of the measurement conditions in this experiment. Two commercially available engine oil additives were used as samples. Sample A is 100% MoDTC, and Sample B is a product containing MoDTC.

Table 1. Measurement conditions

Result

From sample A, three types of MoDTC peaks with different numbers of CH were observed. From sample B, these MoDTC peaks and peaks of hydrocarbon compounds derived from the base oil were observed.

Figure 1. TIC chromatograms and mass spectra by FD method

Figure 2 shows the measured and simulated spectra of C₄₄H₈₈N₂O₂S₆Mo₂. The mass error in the monoisotopic ion (about 2mDa) and the isotope pattern matching were good.

Figure 2. Mass spectra of MoDTC (C₄₄H₈₈N₂O₂S₆Mo₂)

Figure 3 shows the KMD plot of sample B created by msRepeatFinder. By using the KMD plot, it is possible to visualize and confirm the peaks of hydrocarbon compounds and MoDTC.

Figure 3. Mass Spectrum and KMD plot of Sample B

Summary

The FD method of JMS-T2000GC AccuTOF™ GC-Alpha can easily detect high mass components such as MoDTC. Since the FD method does not have chromatogram separation, weak peak may be overlooked in the mixture sample, but it can be visualized and confirmed by using the KMD plot of msRepeatFinder.