| Summary: | 碩士 === 國立臺灣大學 === 化學研究所 === 87 === Matrix-assisted laser desorption/ionization (MALDI) has been proved to be a viable method for identifying additives in polyethylene extracts. The MALDI mass spectra of additive standards were found to be very simple consisting of MH+ and/or MNa+ pseudo molecular ion(s) and with little fragment ions. For real sample often contain more than one additive, the production of only one or two ions for each additive makes the tentative assignment much easier. Post source decay (PSD) and collision induced dissociation (CID) of the pseudo molecular ion provided much higher confidence in the confirmation of the assignment.
MALDI-TOF (time-of-flight) is also used in the analysis of high molecular weight additives. The analysis of high molecular weight additives, such as Chimassorb 944 and Tinuvin 622 indicated that MALDI-TOF was superior to desorption chemical ionization (DCI) and fast atom bombardment (FAB) to the analysis of high molecular weight polymer additives.
The sample crystallization was interfered by the polyethylene dissolved in the extracted solution. The problem could be overcome by adding acetone in the extracted solution. We could reduce the quantity of polyethylene in extracted solution by replacing toluene with acetone. This procedure resulted in good crystallization. In the raincoat extract, we identified the Erucamide, Irganox 1076, Irganox 1010 and Naugard 524 successful.
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