Introduction

Wide pore size distribution GPC/SEC columns have the capability to cover a wide range of molecular weights because each packing material contains pores of multiple sizes. Additionally, when using these columns, high linearity in calibration curves can be achieved.

In this study, we utilized AMR’s wide pore size distribution GPC/SEC column, InfinityLab OligoPore, and compared the separation performance when using a one column and when connecting two columns. We have created calibration curves for each case and present the results.

LC-4000 GPC system

Experimental

Instruments
Pump:　 PU-4180*
Autosampler: AS-4050
Column oven: CO-4060
Detector: RI-4030
* with option units

Conditions
Column: InfinityLab OligoPore (7.5 mmI.D. x 300 mmL, 6 µm) x 1 or x 2
Eluent: Tetrahydrofuran (with stabilizer)
Flow rate: 1.0 mL/min
Column temp.: 40 ºC
Range: STD
Polarity: (+)
Inj. volume: 50 µL
Standard: PS* standard solution dissolved each in mobile phase to a concentration of 0.05 (w/v) %
PS* standard solution (1), PS molecular weight 3090, 580
PS* standard solution (2), PS molecular weight 1200 and n-propyl benzene molecular weight 120
*Polystyrene

Keywords

GPC, oligomer, polystyrene, wide pore size distribution column, InfinityLab OligoPore, refractive index detector

Results

When using one InfinityLab OligoPore column
Figure 1 shows the chromatograms of the PS standard sample and blank sample (same solvent as the mobile phase) when using one InfinityLab OligoPore column, and Figure 2 provides an enlarged chromatogram for the 5–9-minute range, and Figure 3 shows the molecular weight calibration curve created using the PS standard sample. Highly linearity in the calibration curve was obtained.

Fig. 1   Chromatograms of the PS standard sample and blank sample
using one InfinityLab OligoPore column
1: 3090, 2: 120

Fig. 2   Chromatograms of the PS standard sample and blank sample
using one InfinityLab OligoPore column
(enlarged chromatogram for the 5–9-minute range)
1: 1200, 2: 890, 3: 786, 4: 682, 5: 578, 6: 474, 7: 370, 8: 266

Fig. 3   Molecular weight calibration curve created using the PS standard sample
using one InfinityLab OligoPore column

When using two InfinityLab OligoPore columns connected together
Figure 4 shows the chromatograms of the PS standard sample and blank sample (same solvent as the mobile phase) when using two connected InfinityLab OligoPore columns are presented. Figure 5 provides an enlarged chromatogram for the 10–17-minute range, and Figure 6 shows the molecular weight calibration curve. By connecting two columns, especially in the case of the PS standard solution (2), the separation was improved, and peak resolution was enhanced. Additionally, high linearity in the calibration curve was obtained.

Fig. 4   Chromatograms of the PS standard sample and blank sample
using two InfinityLab OligoPore columns connected together
1: 3090, 2: 120

Fig. 5   Chromatograms of the PS standard sample and blank sample  using two InfinityLab OligoPore
column connected together (enlarged chromatogram for the 10–17-minute range)
1: 1320, 2: 1306, 3: 1202, 4: 1098, 5: 994, 6: 890, 7: 786, 8: 682, 9: 578, 10: 474, 11: 370, 12: 266

Fig. 6   Molecular weight calibration curve created using the PS standard sample
using two InfinityLab OligoPore columns connected together

Conclusion

When comparing the use of a single InfinityLab OligoPore column and connecting two columns, it was demonstrated that there are advantages to using two connected columns in terms of separation, while a single column results in shorter measurement times.

The column used in this study has a maximum target molecular weight range of 3,300, and it exhibits high separation capability in the low molecular weight range. It can be applied not only to polystyrene but also to GPC/SEC analysis of materials such as polyurethane and epoxy resins.