Dionex IonPac TCC Series, Руководство по эксплуатации продукта

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IonPac TCC-LP1, TCC-ULP1, and TCC-XLP1
Product Manual Page 10 of 17
Doc. No. 034973-06 ©2005 DIONEX September 2005
3.3. Concentrator Capacity
3.3.1.1. Capacity Considerations for Concentrators
As in all ion exchange systems, the resin has a finite capacity. It can strip a given amount of ions from water. When the
capacity of the concentrator is exceeded, the stripping will not be quantitative. This condition is referred to as column
overload.
When estimating the capacity of a concentrator, one must remember that the column is used in a dynamic state where the
liquid containing the analytes is flowing over the resin at a finite rate. This reduces the capacity somewhat since the analyte
ions have less time to interact with the resin surface.
Low concentrator column capacity creates the following practical implications:
A. Trace analysis of an analyte is difficult in the presence of µg/L concentrations of species which exhibit higher or
similar affinities for the resin. If the dynamic column capacity is exceeded, high affinity ions will displace the
analytes on the ion exchange sites and result in their elution to waste during the loading process.
B. Conversely, qualitative analysis of ions with higher affinities for the resin in the presence of high concentrations of
ions with low affinities is possible. Again, the key to successful analysis is that the ionic content of the high affinity
ion to be quantitated may not exceed the effective column capacity.
C. Do not dilute samples to be concentrated in eluent because the eluent ions elute the ions of interest.
D. A plot of response versus concentration should be generated as in Figure 5, “Linearity of Lithium Concentrator
Injection,” for the determination of the maximum amount of sample or standard that can be quantitatively loaded. In
Figure 4, “Linearity of Lithium Concentrator Injection,” the break in the curve where linearity starts to change is at a
concentration volume of 1 mL of 250 µg/L lithium. For practical purposes the amount concentrated for a series of
samples should be 75% of this value. This will ensure that there is a safety margin built into the concentration
process in case a sample in a series of concentration experiments has a slightly higher ionic concentration.
FIGURE 5
Linearity of Lithium Concentrator Injection