The Column - February 2007 - (Page 23)
February 2007 www.thecolumn.eu.com The Column Tips & Tricks Tips & Tricks:
GPC/SEC Thorsten Hofe, PSS Polymer Standards Service, Mainz, Germany. Q:
How do I find the optimum sample concentration and injection volume for my
GPC/SEC measurements? Sample concentration is an essential part of the
analysis in gel permeation chromatography/size exclusion chromatography
GPC/SEC . Larger signals and improved signal-to-noise S/N ratios can be
achieved by increasing the sample concentration or the injection volume.
However, a large signal is not always the best answer and does not
guarantee accurate molar mass determination Figure 1 . The optimum
concentration and injection volume depends on the sample itself. The first
thing to find out is if the samples are generally high- or low-molecular
weight. Because high molar masses lead to high-solution viscosities, a
high concentration produces a very viscous injection band, so that the
diffusion process on the column can be hindered. When this happens, higher
elution volumes are measured, yielding lower molar masses when a
conventional calibration curve is used. Even when absolute methods are
used e.g., GPC/SEC light scattering the distribution information gets
lost. This problem is less pronounced for low molecular weights. Usually
the recommended GPC/SEC sample concentration for broad technical samples
lies within the range of 0.1–10 g/L, with injection volumes from 2–100
µL. In practice, 2–3 g/L sample concentration is sufficient and a good
value to start with for widely distributed samples PDI 1.5 . For narrowly
distributed samples such as polymer reference materials PDI 1.15 , 1 g/L
is recommended. The injected mass injection volume concentration affects
both the peak position retention volume and the peak shape. For a given
injection volume, lower the sample concentration until the peak position
and shape stay constant. Only the peak area should change as a function of
the injected mass or concentration Figure 1 . If the detector signal
becomes too small because of the low concentration, increase the injection
volume. This guarantees, that the S/N ratio is large enough. In situations
of extremely Author: Thorsten Hofe E-mail: thofe@polymer.de Figure 1:
Elution volume as a function of the sample concentration for various molar
masses. Polystyrene Flow-rate 1 mL/min Inj.vol. 20 µL Column SDV 5 µm
10e5 Å, 8 Detector signal [V] 300 mm Mw 500.000 Mw Concentrations 10
mg/mL 5 mg/mL 1 mg/ml 5.000 Elution volume [mL] high molar masses e.g.,
several millions inject up to 250 µL of sample solution, at a
concentration of 0.1 g/L. With broad samples or small molecules the
concentration range can be increased up to 10 g/L without running into the
peak shape or peak position trouble. For smaller molecules the viscosity
effect does not play a substantial role. Conclusion • The best way to
achieve optimum sample concentration and injection volume with large
molecules is to use a smaller sample concentration and increase the
injection volume. • For small molecules it is best to use high
concentrations and small injection volumes. • Choose a large porous
column at the first column of a column combination. This helps to reduce
the viscosity of the injection band at the beginning of the separation.
Thorsten Hofe is the managing director of columns and reference materials
at PSS Polymer Standards Service GmbH Mainz, Germany . 23
http://www.thecolumn.eu.com
Table of Contents for the Digital Edition of The Column - February 2007
Contents
News
Zosimus
Market Trends and Analysis
Biodiesel - The Alternative Fuel
Biodiesel (FAME) Analysis by FT-IR
Tips and Tricks: GPC/SEC
Q&A
The Column - February 2007
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn030713_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn030713
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn030713_v3
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn021813_v3
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn021813
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn021813_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn020413_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn020413_v3
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn020413
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn011513_v3
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn011513_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn011513
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn120312_v3
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn120312_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn120312
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn112112_v3
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn112112
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn112112_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn110712_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn110712
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn110712_v3
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn102412_v3
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn102412_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn102412
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn100412_v3
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn100412_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn100412
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn092012_v3
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn092012_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn092012
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn090612_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn090612_v3
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn090612
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn082212_v3
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn082212_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn082212
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn080212_v3
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn080212_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn080212
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn071812_v3
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn071812_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn071812
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn070412_v3
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn070412_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn070412
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn062212
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn062212_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn062212_v3
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn060812_v3
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn060812_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn060812
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn051712_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn051712
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn051712_v3
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn050212_v3
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn050212_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn050212
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn041912_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn041912_v3
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn041912
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn040212mkt
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn040212_v3
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn040212_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn040212
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn032112
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn032112_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn030712_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn030712
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn022212_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn022212
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn020112_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn020112
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn011612
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn011612_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn120611
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn120611_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn111611
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn111611_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn110711_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn110711
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn101711
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn101711_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn100711
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn100711_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn092111_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn092111
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn090611_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn090611
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn082211_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn082211
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn080511_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn080511
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn071511_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn071511
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn070111_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn070111
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn061711_hplc
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn061711_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn061711
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn060611_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn060611
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn051811
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn051811_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn050911_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn050911
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn041811_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn041811
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn040111_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn040111
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn031811_v2_test
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn031811_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn031811
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn03042011_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn03042011
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn022111_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn022111
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn020411
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn020411_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn012411_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn012411
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn012711_pittcon
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn120710_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn120710
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn111910
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn111910_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn110510_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn110510
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn102210_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn102210
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn100810_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn100810
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn092410_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn092410
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn090710
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn090710_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn082010v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn082010
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn080610_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn080610
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn072310
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn072310_v2
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn070210
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn062110
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn060710
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn052410
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn051010
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn042310
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn040610
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn031910
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn030510
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn022210
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn020510
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn012210
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn121709
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn120709
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn111909
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn110509
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn102209
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn100809
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn092409
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn090409
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn082009
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn0809
http://digital.findanalytichem.com/nxtbooks/advanstaruk/thecolumn0709_v2
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn0709
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn0609
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn0509
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn0409
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn0309
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn0209
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn0109
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn1208
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn1108
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn1008
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn0908
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn0808
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn0708
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn0608
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn0508
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn0408
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn0308
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn0208
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn0108
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn1107f8
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn1207
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn1107
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn1007
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn0907
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn0807
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn0707
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn0607
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn0507v2
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn0507
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn0407-insert
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn-shimadzu0407
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn0407
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn0307
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn0207
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn0107
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn1206
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn1106
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn1006
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn0906
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn0806
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn0706
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn0606
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn0506
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn0306
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn0206
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn0106
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn1105s
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn1205
https://www.nxtbook.com/nxtbooks/advanstaruk/thecolumn1105
https://www.nxtbookmedia.com