Eluent conditions forODP, C8P, C4P:
Asahipak ODP, C8P and C4P columns can be
used with eluents containing water, methanol
and acetonitrile. In general, acetonitrile
aqueous solutions provide greater efficiency,
especially for compounds containing an aromatic
For control of pH within the range of pH 2 to 13, phosphate, acetate, tris-HCl,
NaCl, KCl, Na2SO4, and trifluoroacetic
acid buffers can be used. Please consult your Asahipak representative if you have
questions about buffering agents not listed above. It is important to note that
the mobile phase should be filtered before use.
Adding organic solvents to salt and buffer
solutions can lead to precipitation of the
salt. Precipitation can occur in the column,
which will often cause a catastrophic rise
in the pressure across the column. If this
does occur, try washing out the precipitate
by reversing the flow on the column with
distilled water. Use a slow flow rate initially
to keep the back pressure low, below 15 MPa.
It is important to check the solubility of
mixed solvent buffers before running a solvent
program. This can be done by making a quick
scouting run in a test tube. Slowly add the
strong eluent to a small quantity of the
starting eluent. If the solution turns cloudy
or white, this means a precipitate is forming.
Other buffer combinations should be tried.
If in doubt, consult your representative.
(1) Water, acetonitrile, and ethanol, either
singly or in mixtures of any ratio, may be
used as eluent. With aqueous ethanol solutions,
the flow rate should be lower than normal,
because of their relatively high viscosity.
(2) Various types of buffers soluble in acetonitrile
or ethanol (such as tetrapropyl-ammonium
acetate or sodium acetate) may be used together
with the above components, so long as no
observable precipitation occurs in the eluent.
(3) Eluents of pH 2.0 to 13.0 can be used.
(1) Buffer solutions such as phosphate, acetate, and tris, with or without NaCl,
KCl, or Na2SO4, may be used.
(2) Eluents of pH 2.0 to 13.0 can be used.