Waters XSelect CSH HPLC Columns - Manual (Page 9)

[ CARE AND USE MANUAL ]
9 XSelect CSH HPLC Columns
b. Impact of Band-spreading Volume on 2.1 mm i.d.
Column Performance
System with 70 µL band-spreading: 10,000 plates
System with 130 µL band-spreading: 8,000 plates
(same
column)
Note: Flow splitters after the column will introduce additional band-spreading.
System optimization, especially in a system that contains a flow
splitter, can have dramatic effects on sensitivity and resolution.
Optimization includes using correct ferrule depths and minimizing
tubing inner diameters and lengths. An example is given in Figure
9 where system optimization resulted in a doubling of sensitivity
and resolution of the metabolite in an LC/MS/MS system.
Figure 9: Non-Optimized vs. Optimized LC/MS/MS System
c. Non-Optimized vs. Optimized LC/MS/MS System:
System Modification Recommendations
1. Use a microbore detector flow cell with 2.1 mm i.d. columns.
Note: Detector sensitivity is reduced with the shorter flow cell path length
in order to achieve lower band-spreading volume.
2. Minimize injector sample loop volume.
3. Use 0.009 inch (0.25 mm) tubing for rest of connections
in standard systems and 0.005 inch (0.12 mm) tubing for
narrowbore (2.1 mm i.d.) systems.
4. Use perfect (pre-cut) connections (with a variable depth inlet
if using columns from different suppliers).
5. Detector time constants should be shortened to less than
0.2 seconds.
7.00 7.50
Non-optimized LC/MS/MS System Optimized System
8.00 7.00 7.50 8.00
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November 2013 720003396EN Rev D VW-PDF