Frans_M_Everaerts_Isotachophoresis_378342.pdf

CONCLUSION 28 1
Tables 10.3-10.5 was taken. The deviations* from the average calibration constant
must be ascribed to the use of the micro-syringe for sample introduction. These values
are listed in Table 10.6.
The tables show that the zones do not have a mutual influence on each other, which
means that the buffer capacity of the counter ion chosen is sufficient.
TABLE 10.6
CALIBRATION CONSTANTS, Kca,, DETERMINED FROM THE VARIOUS EXPERIMENTS
LISTED IN TABLES 10.3-10.5
Ion Concentration K , - ~ lo4 Deviation Deviation
(N)
in KcaI * lo7 (%I
NO,- 0.0125
(30;
CH, COO-
NO,- 0.025
c10;
CH,COO-
NO,- 0.05
(30;
CH,COO-
Average
10.5. CONCLUSION
0.448
0.467
0.462
0.448
0.457
0.459
0.443
0.452
0.461
0.455
-7
t12
+7
With an automatic device for recording zone lengths, a high-resolution detector and
injection via a micro-syringe (a sample valve, as described in section 7.2.3, was even
better), good linearity can be obtained between the amount injected and the distance in
the isotachopherogram between the differential traces of the linear signal of the
conductivity detector.
If the experiments are carried out with care and good equipment is available, no
internal standard need be applied. If the detection of even smaller zones than those in
the tables is required, the profiles as shown in Fig.17.2 must be taken into account.
Among other factors, impurities and different profiles for different zone boundaries may
obscure the quantitative results. The zone boundary of, for instance, acetate with
glutamate is different from that of acetate with morpholinoethanesulphonate, which has
a considerably smaller effective mobility in the operational system at pH 6 (Table 12.1)
than has glutamate.
If a specific detector is available, e.g., the W absorption detector, one can use the
*As already mentioned in section 10.3.2, more accurate data, used for the calculation of the actual
concentrations of the various ionic species via the computer program in Chapter 4, will also improve
the accuracyof Kcal.
-7
+2
+4
-12
-3
+6
1.4
2.6
1.3
1.4
0.4
0.9
2.7
0.7
1.3
1.43