Waters XSelect HSS XP 2.5 µm Columns - Manual (Page 9)

XSelect HSS XP 2.5 µm Columns 9
[ CARE AND USE MANUAL ]
3. Always remember to:
 Use an in-line filter unit (Part No. 205000343) or a
VanGuard Pre-Column.
 Discourage bacterial growth by minimizing the use of
100% aqueous mobile phases where possible.
 Discard and re-prepare aqueous mobile phase every
24-48 hours (if 100% aqueous mobile phase is required).
 Add 5 – 10% organic modifier to aqueous buffer to
minimize bacterial growth (adjust gradient profile
as necessary).
 Filter aqueous portions of mobile phase through a 0.2 µm filter.
 Routinely maintain your water purification system to
ensure it is functioning properly.
 Only use ultra-pure water (18 MegaOhm-cm) and highest
quality solvent possible.
 Consider sample preparation (e.g., solid-phase extraction,
filtration, centrifugation, etc.) when possible.
4. Avoid when possible:
 100% aqueous mobile phases
 HPLC-grade bottled water
 ‘Topping off’ your mobile phases
 Using phosphate salt buffer in combination with
high acetonitrile concentrations (e.g., >70%) due
to precipitation.
5. Don’t assume the column is to blame:
 Investigate cause of column failure
 Monitor backpressure
 Mobile-phase age, bacterial contamination, mobile-phase
precipitation...etc.
 Peak splitting
 Sample quality
 Injection solvent strength.
6. Do not prepare excessive amounts of mobile phase:
 To reduce the chances of mobile-phase contamination
or degradation, prepare enough mobile phase to last for
3 – 4 days. Alternatively, store excess bulk quantities in
a refrigerated environment.
b. Troubleshooting Questions
1. Are you using 100% aqueous mobile phases?
2. What is the age of the mobile phase?
3. Is the mobile phase filtered through a 0.2 µm membrane?
4. Was the mobile phase prepared fresh or topped off?
5. Is the water source of adequate quality?
6. When was the last time the water system was serviced or was
the bottle of water unopened?
7. Is bacterial growth a possibility (pH 7 phosphate buffer is
susceptible to bacterial growth within 24 hours)?
8. If a neat standard is prepared in the initial mobile-phase
conditions and injected, are the problems still observed?
9. If the sample is filtered/purified (i.e., SPE, filtration) is the
problem still observed?
10. Has the quality of the samples changed over time?