Waters ACQUITY UPC2 Torus Columns - Manual (Page 6)

6
[ CARE AND USE MANUAL ]
ACQUITY UPC 2 Torus Columns Care & Use
a. Cleaning
Use the cleaning routine that matches the properties of the
samples and/or what you believe is contaminating the column
(see Table 4). Placing the column on an ACQUITY UPLC
® System
(or HPLC system) will enable the use of a wide range of solvents
and water to improve cleaning. Flush columns with 20 column
volumes of solvent. Increasing column temperature increases
cleaning efficiency. If the column performance is poor after
cleaning and regenerating, call your local Waters office for
additional support.
Note: Using an ACQUITY UPC 2 System is not recommended for
the cleaning and regeneration procedures because recommended
solvents and high concentrations of water are immiscible with
supercritical CO
2
. Rather, the use of an ACQUITY UPLC System
is recommended for cleaning and regeneration.
Polar Samples Non-Polar Samples
1. Water (could also be
a mixture of acetonitrile
and water)
1. Isopropanol (or an
appropriate water/
Isopropanol mixture)
2. Methanol 2. Tetrahydrofuran
3. Tetrahydrofuran 3. Dichloromethane
4. Methanol 4. Hexane
5. Water
5. Isopropanol (followed
by an appropriate water/
isopropanol mixture)
6. Mobile Phase 6. Mobile Phase
Table 3: Column Cleaning Sequence.
Retest the column after using the cleaning procedure to
determine if the specific problem has been fixed. If so, continue
using the column, avoiding samples and solvents that may clog
the column inlet.
b. Effects of Additives
Use of co-solvent additives, such as ammonia or organic
amines, can be used successfully with all Torus columns.
Consider the volatility and detector compatibility when choosing
an appropriate additive. Additives tend to improve peak shape
and control the retention characteristics of analytes, but can
also impart different selectivities. An ammonia additive works
particularly well on Torus DIOL and Torus 1-AA to improve peak
shapes and reduce retention variability. Ion pairing additives
should be used with caution on Torus phases, particularly
those with exposed amines (e.g. Torus 2-PIC and Torus DEA).
Counter ions, such as trifluoroacetate, can bind very strongly or
irreversibly with the stationary phase. It is recommended that
dedicated columns be used with particular ion pairing additives.
c. Aging
Research at the Waters Corporation confirms that there may be
changes in retention with SFC columns due to packing material
surface changes. This is commonly referred to by SFC industry
experts as “Aging or retention drift.” Mobile-phase additives
and methanol can cause changes to the silica or hybrid surface
resulting in retention shifts. When working with a new column,
the column can be flushed with CO
2
/methanol to eliminate
or reduce further shifts in retention. Storage in 100% CO
2
is
recommended to ensure the column retention and selectivity
will be the same from the end of one test to the beginning of
another. The 100% CO
2
will halt the aging process and results
in no additional retention shifts.
Torus columns were designed and developed to not show
the characteristic retention and selectivity changes related
to aging. When exposed to CO
2
/Methanol mobile phases,
these columns show little or no shifts in retention over extended
periods of time.
d. Storage
Purging out any additives with a CO
2
/Methanol mobile phase
is recommended and storing columns in pure CO
2
.