56 May / June 2019
Compounds with locally high intensity at 300℃ on the heat map and compounds with repeating unit structures which are likely to be polymeric at 450℃ were detected (Figure 5).
Figure 3. Mass Spectra of Polymers Using TDP/DART-MS at 400°C
Mass spectra taken at 400°C was compared, and each polymer (PE, PP, PET, PVC, nylon-6) could be differentiated based on the repeating units (Figure 3). Thus, TDP/DART-MS is a simple and rapid method for identification of polymers.
Lubricating Oil
Samples of automotive engine oil were taken at different driving distances: 0 km, 1,000 km, and 5,000 km. Samples were compared using FT-IR and TDP/DART-MS. As a result of FT-IR, no significant difference was detected among samples (Figure 4).
Figure 6. Mass Spectra at 300 °C
Figure 6a. MS/MS Spectra of m/z 296.23
Figure 4. FT-IR of engine oil samples after 0, 1,000, and 5,000 km use.
Figure 6b. MS/MS Spectra of m/z 335.25
Figure 6c. MS/MS Spectra of m/z 408.34 Figure 5. Heat Map
A heat map (horizontal axis: m / z, vertical axis: temperature) of each sample was shown from all the samples (Figure 5).
MS spectra at 300 deg. C (Figure 6) and MS/MS spectra of select compounds (Figures 6a-6c) are shown. By analysing these spectra, additives were characterised including a phenol type antioxidant, an amine type antioxidant, and a salicylic acid type detergent- dispersant. There was no significant difference in the ratio of additive components at 0 km and 1,000 km running, but at 5,000 km, salicylic acid detergent-dispersant and the phenolic antioxidant were significantly decreased. MS spectra at 450℃ are shown in Figure 7.
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