3
–
Operation
Thermo Scientific
Product Manual for IonPac AS31 Columns
Page 17 of 45
155007-01
For Research Use Only. Not for use in diagnostic procedures.
3.6
Regenerant Preparation for the Thermo Scientific Dionex Chemically
Regenerated Suppressor (Dionex CRS 500)
The Dionex Chemically Regenerated Suppressor requires the use of a regenerant solution. Refer
to the product manual (Document No. 031727) for operating instructions.
3.7
Recommendations for Method Development
The Dionex IonPac AS31 is designed for the determination of haloacetic acids in less than 35
minutes using a hydroxide gradient eluent delivered by a Dionex Eluent Generator. In any type
of gradient elution system, it is important to use eluents that produce a minimum shift in baseline
conductivity during the run as well as a fast equilibration time from one run to the next. Potassium
hydroxide is converted to water in the suppressor, making it the preferred source of eluent. As
long as the capacity of the suppressor is not exceeded, the eluent hydroxide concentration has
little effect on background conductivity. For example, a gradient run could begin at 17 mM KOH
and end at 85 mM KOH, with a resulting total baseline change of 1 to 2 µS.
Ensure that adequate equilibration time is allowed between runs. If a downward shift in the
baseline is observed during the isocratic section of the chromatogram, increase the equilibration
time.
You can increase the sensitivity of your system by using sample concentration techniques (see
Section 2.7
, “Sample Concentrators”).
Carbon dioxide readily dissolves in dilute basic solutions, forming carbonate. Carbonate
contamination of eluents can affect the retention times of the anions being analyzed.
Eluents should be maintained under an inert helium atmosphere to avoid carbonate
contamination.
CAUTION
!
