5.3 Performance evaluation of the column
A
bout this section
This section describes how to measure HETP and A
s
. To perform a test of the packed
column, read the information supplied with the media giving you all relevant informa-
tion you need.
Column efficiency test
The efficiency of a column depends on how well it is packed. A poorly packed column
gives rise to uneven flow, resulting in zone broadening and reduced resolution. A
column efficiency test should be performed directly after packing and at regular inter-
vals during the working life of the packed bed. The test is also useful when the separa-
tion performance is seen to deteriorate. Poor test results indicate that the media
should be repacked or replaced.
A widely used method for expressing the efficiency of a packed bed is in terms of the
height equivalent to a theoretical plate (HETP) and the peak asymmetry factor (A
s
).
These values can easily be determined by applying a sample of for example acetone or
NaCl solution to the column.
Measuring HETP and A
s
Measuring the HETP and A
s
values is the best way to judge the condition of the packed
column. A packed column can look good, but still need repacking for optimal perform-
ance. Always check the column after packing and regularly between runs to ensure
best column performance. Follow the specific instructions for the packed media to
optimize the testing protocol.
5 Operation
5
.3 Performance evaluation of the column
72
BPG Columns Operating Instructions 29193223 AB
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