4
CORTECS and CORTECS Premier 2.7
µ
m Columns
[ CARE AND USE MANUAL ]
b. pH Range
The recommended operating pH ranges for CORTECS
columns can be found in table 3. A listing of commonly used
buffers and additives is given in Table 2. Additionally, the
column lifetime will vary depending upon the operating
temperature, the type, and concentration of buffer used. For
example, the use of phosphate buffer at
pH 8 in combination with elevated temperatures will lead
to shorter column lifetimes.
c. Solvents
To maintain maximum column performance, use high quality
chromatography grade solvents. Filter all aqueous buffers prior
to use through a 0.2 µm filter. Pall Gelman Laboratory Acrodisc®
filters are recommended. Solvents containing suspended
particulate materials will generally clog the outside surface of
the inlet distribution frit of the column. This will result in higher
operating pressure and poorer performance. See Section VI
for more information.
d. Pressure
1. The 2.1 mm I.D. CORTECS and CORTECS Premier 2.5 µm
Columns can tolerate operating pressures up to 18,000
psi (1241 bar or 124 MPa).
2. The 3.0 mm I.D. CORTECS Columns can tolerate
operating pressures up to 18,000 psi
(1241 bar or 124 MPa).
3. The 4.6 mm I.D. CORTECS and CORTECS 2.5 µm
Columns can tolerate pressures up to 10,000 psi
(700 bar or 70 MPa).
e. Temperature
Temperatures between 20–45 ˚C are recommended
for operating CORTECS Columns in order to enhance
selectivity, lower solvent viscosity, and increase mass
transfer rates. When operating at high pH, lower operating
temperatures are recommended for longer column lifetime.
Working at high temperatures (e.g., >45 °C) may also result in
shorter column lifetimes.
III. COLUMN USE
To ensure the continued high performance of CORTECS
Columns, follow these guidelines:
a. Sample Preparation
1. Sample impurities often contribute to column
contamination. One option to avoid this is to use Waters
Oasis™ Solid-phase Extraction Cartridges/columns or
Sep-Pak™ Cartridges of the appropriate chemistry to
clean up the sample before analysis. For more information,
visit
www.waters.com/sampleprep
.
2. It is preferable to prepare the sample in the operating
mobile phase or a mobile phase that is weaker than the
mobile phase for the best peak shape and sensitivity.
Acetone should not be used as a sample solvent/diluent
unless a Hexane Tetrahydrofuran Compatibility Kit has
been installed.
3. If the sample is not dissolved in the mobile phase, ensure
that the sample, solvent, and mobile phases are miscible
in order to avoid sample and/or buffer precipitation.
4. Filter sample with 0.2 µm membranes to remove particulates.
If the sample is dissolved in a solvent that contains an organic
modifier (e.g., acetonitrile, methanol, etc.) ensure that the
membrane material does not dissolve in the solvent. Contact
the membrane manufacturer with solvent compatibility
questions. Alternatively, centrifugation for 20 minutes at
8000 rpm, followed by the transfer of the supernatant liquid
to an appropriate vial, could be considered.
5. For Hydrophilic Interaction Chromatography (HILIC)
separations, the samples must be prepared in a high
percentage of organic solvents (e.g., 95% acetonitrile).
See “Getting Started with CORTECS HILIC Columns”
section for additional information.