Foundation GPC Part 4 – Organic Gel Permeation Chromatography

Columns and Applications

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Introduction

There are a wide variety of columns available for organic GPC

This presentation shall introduce the most common types of column

This information can act as a reference

Applications on the various columns shall also be discussed

We have performed many applications on our columns, so even if your application is not shown here, we’ve probably done it!

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Column Types

The factor that principally controls which type of column is selected for a GPC experiment is the solvent

Many polymer dissolve in only very limited numbers of solvents

The columns used must be compatible with the solvent of choice

Most importantly, the size exclusion mechanism must be maintained

Polymer Laboratories have two main ranges of GPC column for organic solvents

The properties of each range that must be considered when selecting them for an application shall be presented

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Organic GPC

The vast majority of commercially important polymers are only soluble in organic solvents such as tetraydrofuran, toluene or trichlorobenzene

For these applications a column packed with material compatible with these solvents must be chosen

Almost universally columns packed with insoluble porous beads of polystyrene cross-linked with divinyl benzene are used (PS/DVB)

The majority of manufactures use columns of this type

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Styrene/Divinyl Benzene Columns - PLgel

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PLgel solvent Compatibility

Columns can be used in a wide range of solvents

Transfer between solvents is possible assuming care is taken

The column user guide details the procedure

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Adsorption of Polystyrene Standards in DMF

Column : PLgel 5um 500Å 300x7.5mm

PS/DVB columns are excellent in many solvents, but remember that although the column may be used in certain solvents this does not mean SEC will occur - the example here is polystyrene standards running in DMF

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PLgel Column Range

The extensive range of products has variation in pore size, particle size and column dimensions

The packing materials are identical in terms of surface chemistry

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Low Molecular Weight High Resolution Separations

Individual pore size columns are ideal for these applications

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Applications in Standard GPC Solvents

With no danger of shear degradation, 3um particles can be employed

Extremely high efficiency separations are obtained but only if the dispersion in the system is kept low

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Combination of Individual Pore Size Columns

Traditional approach to increasing MW operating range of column set

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PLgel MIXED Bed columns

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Individual Pore Size or MIXED Gel Columns?

PLgel 5µm 10E4Å

Optimum resolution over limited MW range

PLgel 5µm MIXED-D

Equal resolution over wider range of MW

Both types still have the similar pore volume, just the MW range over which it is available that changes

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Individual Pore Size Combination Versus MIXED Gel Columns - Calibration Data

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Individual Pore Size Combination Versus MIXED Gel Columns - Polydisperse Sample

Eluent THF

Flow rate 1.0 ml/min

Detector UV 254nm

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PLgel MIXED Bed Calibrations

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PLgel MIXED Bed Application Guide

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Applications on MIXED Bed Columns

These samples are complex with polymer and oligomer components

MIXED columns with a wide resolving range are ideal in these cases

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High Polarity Separations on PLgel

PLgel can be used with very polar solvents

Many samples can be analysed under these conditions

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High Temperature Applications on PLgel

PLgel is very stable to high temperatures

The same material is used as for low temperature separations

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Extreme GPC

In the most extreme case very high temperatures are required

The same PLgel material is employed even under these conditions

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Unusual Peak Shapes in GPC

Not all peaks are Gaussian

Multimodal peaks are common in complex polymers

The presence of oligomers leads to complex chromatograms

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Analysis of Multi-Component Systems

Interpreting the complex distributions of some samples can be challenging

Understanding the chemistry used to make the material is a definite help

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Troublesome Applications on PLgel

Some applications are at the border of what is possible on PLgel columns

It may be that in these cases alternative packing materials will be required

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PLgel LS Columns

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PS/DVB miniMIX Columns

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miniMIX Solvent Consumpsion

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Applications with miniMIX Columns

Under the right conditions miniMIX columns perform just as well as their analytical counterparts

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PS/DVB Preparative Columns

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Comparative Preparative Separations

Preparative columns give identical chromatography to analytical columns under the right conditions Method development can be performed on the analytical columns, reducing the risk of damage to expensive preparative coluns

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PlusPore PS/DVB Columns

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PlusPore Calibrations

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Advantages of the PlusPore Range

With individual pore size columns dislocations are fairly common

The PlusPore range contains only one type of packing material with a wide resolving range

Dislocations cannot occur on this type of column

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Columns 2xPLgel 3µm 100Å 300x7.5mm 2xOligoPore 300x7.5mm

Eluent THFFlow rate 1.0ml/min

Effect of Increased Pore Volume

Both columns have a similar exclusion limit but OligoPore has greater pore volume than PLgel 100Å. Hence the slope of the curve is shallower leading to greater resolution for columns of the same efficiency

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Applications in with PlusPore Columns

The extended pore volume of the PlusPore range leads to very high resolution

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High Resolution OligoPore Separations

The OligoPore column if filled with 6um packing material, but due to a very large pore volume it gives resolution similar to a 3um PLgel

As a result of the larger particle size, OligoPore is very resilient to extra-column dispersion