26.12.2012 Views

Frans_M_Everaerts_Isotachophoresis_378342.pdf

Frans_M_Everaerts_Isotachophoresis_378342.pdf

Frans_M_Everaerts_Isotachophoresis_378342.pdf

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

14 PRINCIPLES OF ELECTROPHORETIC TECHNIQUES<br />

b<br />

0 L<br />

C<br />

, conatant ,,,<br />

Fig.2.5. Separation of a mixture of anions according to the isotachophoretic principle. The sample<br />

A+B+C is introduced between the leading anionic species L and the terminating anionic species T.<br />

A suitable cationic species is chosen as the buffering counter ion. The original conditions are shown<br />

in (a). After some time (b), some mixed zones are obtained according to the moving boundary<br />

principle. Finally (c), all anionic species of the sample are separated and all zones contain only one<br />

anionic species of the sample (‘ideal case’).<br />

For this steady state, all zones must have identical migration velocities, determined<br />

by the migration velocity of the anionic species of the leading electrolyte. Considering<br />

the zones L, A, B, C and T (see Figure 2.5~):<br />

v, = VA = V B = vc = VT<br />

or<br />

m,E, = mAEA = mBEB = m,Ec = mTET (2.4)<br />

Eqn. 2.4 will be called the ‘isotachophoretic condition’ and it is characteristic of<br />

isotachophoretic separations.

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!