[Zurück]

S. Morlock, J. Kuebel, T. Beskers, B. Lendl, M. Wilhelm:
"Online Detection of Functional Groups in SEC via Quantum Cascade Laser IR Spectroscopy";
Macromolecular Rapid Communications, 39 1700307 (2018), S. 1 - 5.

The development of coupled techniques based on chemically sensitive
detectors, such as FTIR or NMR spectrometers, for size exclusion chromatography
(SEC) provides sophisticated methods for determining the
molecular-weight-dependent chemical composition in polymers. However,
the detection of rare functionalities such as end groups or branching points
presents a challenge, especially for online coupled SEC detection, which is
based on low-concentration chromatography. To address this issue, for the
first time, an external cavity quantum cascade laser (EC-QCL) infrared spectrometer
is coupled to an SEC. The system is evaluated using polystyrene/
poly(methyl methacrylate) (PS/PMMA) blends. The current limit of detection
for the carbonyl (PMMA) stretch vibration at 1730 cm−1 with this technique is
3.5 μg PMMA on a semipreparative column (typical load of 2.5 mg polymer in
total). That equals 0.15 mol% of PMMA in the PS/PMMA blend and corresponds
to one carbonyl group per 70 kg mol−1 polymer.

http://dx.doi.org/10.1002/marc.201700307