Waters High Strength Silica Columns - Manual (Page 7)

[ Care and Use ManUal ]
HSS HPLC Columns 7
XIII. CoLUMn CLeanInG, ReGeneRatInG anD stoRaGe
a. Cleaning and Regeneration
A sudden increase in pressure or shift in retention or resolution may
indicate contamination of the column.
Flush with a neat organic solvent to remove the non-polar
contaminant(s). If this flushing procedure does not solve the problem,
purge the column with a sequence of progressively more non-polar
solvents. For example, switch from water to tetrahydrofuran to
methylene chloride. Return to the standard mobile phase conditions
by reversing the sequence.
b. Storage
For periods longer than four days, store the column in 100%
acetonitrile. Do not store columns in buffered eluents. If the mobile
phase contained a buffer salt, flush the column with 10 column vol-
umes of HPLC grade water (see Table 2 for common column volumes)
and replace with 100% acetonitrile for storage. Failure to perform
this intermediate step could result in precipitation of the buffer salt in
the column when 100% acetonitrile is introduced.
Completely seal column to avoid evaporation and drying out of the bed.
Note: If a column has been run with a formate-containing mobile
phase (e.g., ammonium formate, formic acid, etc.) and is flushed
to remove the buffer, slightly longer equilibration times may be
required after the column is re-installed and run again with a formate-
containing mobile phase.
X. tRoUbLesHootInG
Changes in retention time, resolution, or backpressure are often due
to column contamination (refer to “Column Cleaning, Regenerating
and Storage”). Information on column troubleshooting problems may
be found in HPLC Columns Theory, Technology and Practice, U.D.
Neue, (Wiley-VCH, 1997) or the Waters HPLC Troubleshooting Guide
(Literature Code 720000181EN).