Waters Styragel Columns - Manual (Page 8)

[ Care and Use ManUal ]
Styragel Columns 8
b. Storing the Column
If you will be using the column again in less than 24 hours, special storage
procedures are unnecessary. However, be sure that the columns never dry out.
For longer storage periods, return the column to its box with the end plugs
firmly in place for storage. Do not leave a column at elevated temperatures
without solvent flow.
For maximum column life, avoid temperature cycling. Maintain operating
temperature and reduce flow rate to 0.1 mL/min when columns are not in use.
To restart the column, maintain a flow rate of 0.1 mL/min and, if applicable,
increase the temperature gradually over 10 hours. Then set the flow rate to
the desired operating flow.
c. Efficiency Testing
Waters columns are tested for adherence to our specifications. Slight variations
may occur depending on:
• The type and condition of equipment used
• The nature of the sample
• Instrument settings
Perform your own efficiency tests. To test both your system and each column
in the system, carry out both of these tests:
• Instrument band-spreading test
• Column-efficiency test
When to perform efficiency tests
Perform efficiency tests each time you add columns or otherwise change your
system. Then, as you use the system, conduct efficiency tests on a regular
schedule.
If problems occur during normal operation of the column, repeat the conditions
for the initial efficiency tests and compare the results. Monitor instrument
band spreading by performing a column efficiency test without the column in
line. Resolve excessive band spreading before installing columns.
1) Testing Instrument Band Spreading
Test procedure
The band spreading of a properly operating system should be less than
150 µL
(75 µL for solvent efficient columns) . To determine the band spreading
of your system:
1. Remove the column(s) from the system.
2. Connect the inlet and outlet tubing with a zero dead-volume
union.
3. Set the flow rate to 1.0 mL/min.
4. Use a fast chart speed to obtain a peak of easily measurable
width. If you use a data system, set the sampling rate to at least
10 data points per second. You may need to adjust the detector
sensitivity to keep the peak on scale.
5. Inject the same sample as for a plate count determination (see
Table 4, 5, or 6).
6. Measure the width of the resulting peak at 4.4% of the peak height
to obtain a value in µL.
Figure 5 illustrates the 5 sigma method, in which the width of the peak (w) is
measured at 4.4% of the peak height (h).
Figure 5. Method for Calculating Band Spreading
Diluted/Distorted Sample Band
Add calculation N= 25 (Vr/W)^2