Page 16 - Solutions for Plastic Evaluation

Evaluation of Raw Materials
Evaluation of Impurities and Byproducts
MALDI-TOFMS

Evaluation of Plastic Materials Analysis of Trace Homopolymer Components in Copolymers
The following is an example of using an SEC-AccuSpot-AXIMA system to analyze trace homopolymer components in samples, based
on a model sample consisting of the binary copolymer poly(methyl methacrylate-b-n-butylmethacrylate) (poly(MMA-b-n-BMA)). A
microscale separation column was used to load all components onto MALDI sample plates without any sample loss. Fig. 1 shows the
SEC chromatogram of poly(MMA-b-n-BMA). The AccuSpot system was used to collect fractions at six second intervals, from the time the
primary peaks started eluting until they finished (for 5 minutes, from 8 minutes 20 seconds to 13 minutes 20 seconds), and load 50 sample
spots onto a MALDI sample plate. Each spot was measured in a MALDI-TOFMS system to obtain mass spectra (Fig. 2) corresponding to
elution times. The mass spectrum obtained from each fraction indicates a different molecular weight distribution.
Evaluation of Raw Materials Analytical Conditions

∙ SEC Column: Shodex GF310A-1E (1.0 mm I.D. × 250 mm)
Flowrate: 10 µL/min; Eluent: THF
Detector: UV ( λ = 220 nm); Injection volume: 1 µL
Product Evaluation Mixture of matrix and cationizing reagent:
∙ AccuSpot Spot interval: 6 sec, 1 µL/well

0.2 µL/well

Cationizing reagent: Na-TFA-10 mg/mL -THF
∙ MALDI-TOFMS Matrix: Dithranol-20 mg/mL- THF
Fig. 1 SEC Chromatogram of Poly(MMA-b-n-BMA)
Product Information (Fig. 3). The 142 interval between adjacent peaks indicates that the molecular weight distribution with a peak near m/z 1200 (marked
The fraction collected after 11 minutes and 18 seconds shows a detected molecular weight distribution not observed before separation
with ● ) corresponds to the PnBMA homopolymer. Similarly, the 100 interval between adjacent peaks indicates that the molecular weight
distribution with a peak near 1800 (marked with ■ ) corresponds to the PMMA homopolymer. These results indicate that the poly(MMA-
b-n-BMA) in this example, contains trace amounts of the homopolymer components PnBMA and PMMA.

Fig. 2 MS Spectra of SEC-Separated Fractions

Fig. 3 Detection of Homopolymer Components

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