Application
News
No. B85
MALDI-TOF Mass Spectrometry
Thermal Deterioration Analysis of Polymers using a
Linear Benchtop MALDI-TOF MS
LAAN-A-TM-E056
In recent years, MALDI-TOF mass spectrometers are being
utilized more and more for simple molecular weight
measurement and profiling of synthesized products and
high-molecular compounds. This is because instruments of
this type have several advantageous features: singly-charged
ions are generated so molecular weights can be recognized
easily, the mass range is wide, and there are many solvent
options because the sample is dried before measurement.
On the other hand, due to changes in social conditions over
the last several years, government offices, universities and
private enterprises strongly request the reduction of costs for
both the introduction and running of instruments used for
such applications. The benchtop "MALDI-8020" MALDI-TOF
mass spectrometer is a new instrument that can adequately
meet these market needs. The noteworthy point about this
instrument is that it has a shorter flight tube, which is the key
feature of its small size, while retaining performance equal to
or higher than that of a conventional model.
In the process of the recent development and quality
control of materials and chemical products, there is an
increasing need to simply and quickly examine the
degradation of synthesized polymer products based on
chemical changes at a molecular level in association with
durability tests. This article introduces an example of
analyzing the thermal degradation of polymers using the
MALDI-8020 mass spectrometer.
Y. Yamazaki
Benchtop MALDI-TOF Mass Spectrometer,
MALDI-8020
The MALDI-8020 (Fig. 1) is a compact-design, minimal-space
linear mode-only MALDI-TOF mass spectrometer. Its
performance in linear mode (positive ion) is comparable to the
same mode of a conventional MALDI-TOF mass spectrometer.
Equipped with a 200 Hz solid laser and a load lock chamber
mechanism that enables a target plate change in a few minutes
while maintaining the degree of vacuum at the measuring
position, the instrument ensures rapid measurements.
The flight tube of this instrument is shortened to 0.85 m long;
however, the mass resolving power is as good as that of a
conventional model. The instrument has a practical resolving
power that enables isotope separation even near m/z 4000.
Degradation Model Creation and
Measurement Conditions
We prepared degradation model samples by repeating the
process of heating and molding polymers 0, 1, 4 and 10 times.
We dissolved these polymers without treatment and used
the solution for MALDI measurement. In addition, we
introduced these polymers, after dissolving in a good solvent,
into a poor solvent, then collected supernatants containing
oligomers with no precipitates (dissolution/reprecipitation
method), and used this solution for MALDI measurement. We
used dithranol (20 mg/mL, chloroform) for the matrix, and
Na-TFA (10 mg/mL, THF) as a cationization agent.
Statistical Analysis
Statistical analyses including multivariate analysis are
effective tools to detect defective products by comparison
with normal products; however, some commercially
available software requires advanced knowledge of
statistical analysis, which may give the impression of a
barrier to the use of such software. The newly developed
eMSTAT Solution
TM
provides an intuitive and prompt
statistical analysis. We used this software for analysis.
Fig. 1 MALDI-8020 Benchtop MALDI-TOF MS
Fig. 2 Mass Spectrum of General-purpose Polyester
* Polymers dissolved to 10 mg/mL were measured without
treatment.
Number of times heated
0 times
1 time
4 times
10 times
% Intensity
0
20
40
60
80
100
m/z
1000 2000 3000 4000 5000 6000
0
20
40
60
80
100
m/z
3000 3500
3017.7
3271.8
3525.7
3780.2
3017.7
3272.0
3526.0
3779.9
3017.8
3271.8
3527.1
3780.9
3017.0
3271.2
3525.2
3779.2
% Intensity
