Waters Styragel Columns - Manual (Page 5)

[ Care and Use ManUal ]
Styragel Columns 5
3. With the system at 90 ˚C, convert to the high-temperature solvent
at 0.1 mL/min using 12 mL per column. Then purge the system
for a minimum of four column volumes at 0.2 mL/min.
When using a bank of columns, multiply the number of column
volumes specified in the procedure by the number of columns
being used.
4. Convert to the high-temperature solvent using a flow rate of 0.1
mL/min. Use at least 20 mL per column.
5. Increase the temperature to the final conditions over a minimum
of four hours while continuing to purge the column at 0.1 mL/min.
Never exceed 150 ˚C.
Increase the temperature to the final conditions over a minimum
of four hours while continuing to purge the column at 0.1 mL/min.
Never exceed 150 ˚C.
6. Adjust the flow rate to the final operating conditions. The optimal
flow rate is 0.3 ml/min.
Adjust the flow rate to the final operating conditions. The optimal
flow rate is 0.3 ml/min.
Returning to room temperature
To return the columns to room temperature, reverse the above procedure.
Alternatively, set the flow rate to 0.1 mL/min and reduce the temperature by
10 ˚C every 30 minutes.
Restarting the column
To restart the column, maintain a flow rate of 0.1 mL/min and increase the
temperature to the desired temperature over 10 hours. Then program the
desired operating flow rate.
For maximum column life, avoid temperature cycling. Maintain operating
temperature but reduce flow rate to 0.1 mL/min when columns are not
in use.
c. Preparing the Sample
Good sample preparation prolongs column life and ensures reproducible
results. Take into account factors such as the capacity of the column,
sample viscosity, and the type and sensitivity of the detector. Remove
micro particulates with a 0.45 µm filter. Refer to Waters catalog for filter
choice and solvent compatibility chart.
Reactive polymers
Some reactive polymers (such as epoxies) may “condition” the column.
Improve column life and reproducibility by dedicating columns to specific
classes of reactive polymers.
Sample concentration
Sample concentration affects both viscosity and injection volume. While small
sample amounts produce narrower peaks, viscous samples may require larger,
more dilute samples. Table 2 lists the recommended concentration of sample
for optimal results.
High-molecular-weight polymers
High-molecular-weight polymers are especially susceptible to viscosity
problems. When analyzing high-molecular-weight polymers, use the con-
centrations indicated in Table 2. Run narrow-distribution polymers, such as
polystyrene standards, with an injection volume of 50 µL per column
(20 µL per
column for solvent efficient columns) at a concentration of 0.02 percent.
Polystyrene standards with molecular weights of approximately four million or
greater become increasingly susceptible to degradation by shearing in solu-
tion. Shearing is indicated by molecular-weight distributions that are broader
than expected. With proper handling, polymers with molecular weights as high
as 20 million can be handled successfully.