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Frans_M_Everaerts_Isotachophoresis_378342.pdf

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314<br />

TABLE 13.2<br />

AMINO ACIDS, PEFTIDES AND PROTEINS<br />

OPERATIONAL SYSTEM AT pH ABOUT 9 SUITABLE FOR ANIONIC SEPARATIONS<br />

Solvent: H, 0.<br />

Electric current (/.LA): CQ. 50-100.<br />

Electrolyte<br />

Leading Terminating<br />

__-<br />

Anion 5-Br-2,4-diOH-C6 H, COO- 0-Ala- (recrys-<br />

tallized from<br />

waterethanol)<br />

Concentration 0.004 M CQ. 0.01 M<br />

Counter ion HOC, H, N'H Baa+ [added as Ba(OH),]<br />

PH 9.0, 9.2, 9.4, 9.6 Ca. 10.5<br />

Additive 0.05% Polyvinyl None<br />

alcohol (Mowiol)<br />

TABLE 13.3<br />

OPERATIONAL SYSTEM AT pH ABOUT 9 SUITABLE FOR ANIONIC SEPARATIONS<br />

Solvent: H, 0.<br />

Electric current (fiA): Ca. 50-100.<br />

Electrolyte<br />

Leading Terminating<br />

Anion 5-Br-2,4-diOH-C6 H, COO- P- Ala- (recrystallized<br />

from wa tere thanol)<br />

Concentration 0.004 M Ca. 0.01 M<br />

Counter ion L-Lys+ Ba2+ [added as Ba(OH), J<br />

PH 9.1, 9.2, 9.4 Ca. 10.5<br />

Additive 0.05% Polyvinyl<br />

alcohol (Mowiol)<br />

None<br />

The leading ion in these systems was chosen because its effective mobility is almost<br />

identical with the effective mobility of the carbonate (hydrogen carbonate) ion. In the<br />

linear trace of the conductivity detector, the carbonate (hydrogen carbonate) step is no<br />

longer visible*. The leading ion, however, has a W absorption. If too much carbonate<br />

(hydrogen carbonate) is present, it is present in the UV trace, which is used only to mark<br />

the UV-absorbing zones and has so far not been applied for qualitative determinations.<br />

The carbonate (hydrogen carbonate), if present, is enriched just before the zones of the<br />

isotachophoretic 'train', as can be seen in Fig. 13.1.<br />

*This simplifies the qualitative information considerably.

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