chromatography • spectroscopy 49
to the high temperatures applied various safety features such as auto-lock doors and gas sensors are built into the system.
Te first step in high temperature polymer analysis is ensuring an efficient dissolution and filtration of samples prior to GPC/SEC analysis without risking any unwanted polymer degradation.
Te polymer chain is stressed by heat and shaking. Te best way to gently dissolve these polymers is moving the sample carefully and applying an individual temperature program until full dissolution has occurred.
Te DF-8321 sample processing unit of the new system can process up to 24 samples with a frequency of 10 to 100 rounds per minutes at temperature programs ranging from 40 to 220°C. In addition samples can be filtered automatically to avoid contamination of the column and system.
Te standard detection in GPC/ SEC applications is refractive index (RI) detection. Te data shown below are measured with a unique dual-flow RI detector, similar to the RI detector of the
A
was developed to complement the new high temperature GPC system when using the maximum temperature range up to 220°C. Fig. 4 shows examples of polymer analysis with RI-detection at 145°C and at 220°C.
Fig. 3. Baseline stability at various conditions.
basic EcoSEC system which was described in detail in Eurolab June 2013.
Te combination of a high performance heating system and the dual flow RI detector speeds up equilibration time and reduces the baseline noise in an effective way.
Fig. 2 shows the equilibration of column temperature and detector signal at a flow rate of 1ml/min and a target temperature of 145°C. After 180 minutes both parameters show excellent stability. Fig. 3 depicts the extremely low baseline noise
of the RI signal for different solvents and temperatures.
Separation of polymers Te high temperature GPC/ SEC system delivers consistent results over a broad range of conditions. For optimum performance the GPC column should be carefully selected to ideally fit the temperature and solvent conditions. Te TSKgel family of GPC/SEC columns offers a wide range of GPC columns with individual pore sizes but also mixed bed and multi-pore columns exhibiting linear mass calibrations. Te TSKgel GMHHR- HT2 series
B
Conclusions Te combination of HLC- 8321GPC/HT and TSKgel GMHHR HT2 is a powerful tool for GPC measurement of engineering plastics. An accurate sample preparation is just as important as a stable RI detector baseline. A stable RI detector baseline is required for successful experiments in particular for repeatable and reproducible molar mass average calculations.
Te repeatability and reproducibility of the molar mass averages have been shown to significantly increase by replacing a conventional RI detector with a dual-flow RI detector.
For more information ✔ at
www.scientistlive.com/eurolab Jens Reichenberger is with Tosoh Bioscience GmbH, Stuttgart, Germany.
www.tosohbioscience.de. Data generated at Tosoh Corporation and Tosoh Hitech by Fumiya Nakata; Shuji Kumagai, Kazunari Fukugawa and Satoshi Fujii
Fig. 4. GPC Analysis at Various Temperatures A: Polymethylepentene (PMP) @ 145°C, mobile phase: 0.05% BHT in ODCB, column: TSKgel GMHHr-H HT x 2; B: Polyphenylenesulfide (PPS) @ 220°C, mobile phase: 1-chloronaphtalene; column: TSKgel GMHHR-H(S)HT2 x 2.
www.scientistlive.com
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