Migration of Sample Ions

The actual, or observed, migration of sample ions is the net result of two vectors, electrophoretic and electroosmotic migration. The observed mobility, )Iq, is expressed simply as ... 

Migration of sample ions through a capillary is affected by both electrophoretic and electroosmotic vectors. Separations can be carried out in any of the following... 

Lin and Chao (1991) studied the variation of the cation distribution with the lanthanum exchange level in hydrated La,Na-Y zeolites by two-dimensional 23Na nutation NMR spectra in which the chemical shift and the quadrupole interaction could be separated. They proposed that the mobility of both water molecules and sodium ions can be reduced by lowering the temperature of the sample, and the migration of lanthanum ions from supercages to small cages causes the redistribution of sodium after dehydration... 

At 2450 MHz, the field oscillates 4.9 x 10 times per second and sympathetic agitation of the molecules generates heat. The quantity of heat produced by dipole rotation is dictated by the dielectric relaxation time of the sample, which in turn, is affected by temperature and viscosity. Ionic conduction on the other hand, occurs by migration of dissolved ions with the oscillating electric field. Heat is generated by frictional losses that depend on the size, charge and conductivity of the ions and on their interactions with the solvent. 

A low concentration of an ionic surfactant in the capillary electrolyte can also be used to modify the migration behavior of sample ions. A cationic surfactant such as cetyltrimethylammonium chloride (CTAC) is often used for anion separations, and SDS is often used when cations are to be separated. Kenata et al. [11] found that CTAC decreased the effective electrophoretic mobilities of several inorganic anions as the result of two processes ... 

---