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4
– Example Applications
membranes, ammonia and amines are released from the screen and membrane surfaces,
especially in a newly installed Dionex CERS 500e.
To reduce the amine blank, follow the Dionex ERS 500e start-up procedure in
"Start-up Procedure for the Dionex Electrolytically Regenerated Suppressor (Dionex ERS
500)." The amine blank is normally reduced to a constant level after 24 hours of operation. A
typical blank is shown in Figure , "Dionex IonPac CS12A Blank and Standard Analysis." The
use of high purity chemicals helps to reduce the blank concentrations.
4.2 Dionex CERS 500e Conditioning
Since the Dionex CERS 500e is a high-capacity anion exchange device which supplies the high
concentration of hydroxide for acid neutralization, the hydrolysable ions such as Mg
in hydroxide forms may be precipitated in the Dionex CERS 500e. In general, when standard
cation in water solutions are employed for system calibration, it is possible that Mg
may be precipitated due to the high hydroxide concentration. These cations are then "carried
over" to the first acid run. To avoid the hydrolysis of the alkaline earth metals during standard
calibration, the Dionex CERS 500e is "conditioned" by running a complete pretreatment cycle
of acid (preferably 24% sulfuric acid) prior to standard runs. Follow the Dionex CERS 500e
acid treatment procedure below prior to each standard run.
A. Confirm that the system functions properly.
B. Set "Sample Valve" to Load Position and load 24% sulfuric acid.
C. Switch the sample valve to Inject position and flush the sample loop with deionized
D. After the sulfuric acid passes through the neutralizer and IC injection valve
The above steps are applied only when standard calibration is performed. However, if the
standard injection is made immediately after the sample runs (acid samples) the Dionex CERS
500e acid pretreatment is not required.
If the standard run is not started within 20 minutes after the acid calibration step, the overall
process must be repeated. When multiple point calibration is performed, the Dionex CERS 500e
acid pretreatment can be made any time after the beginning of the analytical separation.
4.3 System Calibration
The analytical blank should be incorporated into the calibration curve. One or two level
standards are usually required to calibrate the Ion Chromatograph. For trace analysis, typical
standard concentrations are 2 to 5 times sample concentrations. For example, for anions, if the
sample contains 50 ppb each of Cl
250 ppb each of these anions. For cations, if the sample contains 10 ppb each of K
2+
Ca
, the standard calibration should not exceed 50 ppb each of these cations.
4.3.1
Analysis of Acid Samples Containing High Concentrations of Transition Metals
If a sample contains transition metals in ppm (mg/L) levels, these elements may interfere with
cation detection by suppressed conductivity. The additional of complexing agent such as
pyridine-2,6-dicarboxylic acid (PDCA, Item # 039671) to the CS12A eluent is required to
selectively remove transition metals from the eluent via the suppression system.
Thermo Scientific
031956-11
water.
(approximately 4–6 minutes with the collection coil installed or 1-2 minutes without
the collection coil installed), the system is ready for standard injection.
Product Manual for the ERS 500 Suppressor
For Research Use Only. Not for Use in Diagnostic Procedures.
–
3–
2–
, NO
and SO
, the standard calibration should not exceed
4
Section
3.2,
2+
2+
and Ca
2+
2+
and Ca
+
2+
, Mg
and
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