th  - 1988 - 51st ENC Conference

MON 9:25
HIGH RESOLUTION ELECTROPHORETIC ~ (ENMR) OF A MIXTURE:
Timothy R. Saarlnen' and~les S. Johnson, Jr., University of North
Carolina, Dept. of Chem., Chapel Hill, NC 27599-3290
Electrophoretic mobilities have been measured in situ using
pulsed field gradient NMR (PFGNMR). Several components in a mixture
can be studied simultaneously by Fourier transformation of the second
half of the spin echo. For a U-tube configuration application of an
electric field across the sample resu/ts ~n a cosinusoidal modulation
of spectral peak amplitudes, cos(Kv= t) where K equals the area of the
gradient pulse times the gyrcmagnetic ratio, v: is the drift velocity
of the i'th species, and t is the duration of the electric field
pttlse. By working at low ionic strengths electric fields of up to 50
V/cm could be applied for i sec before convection ~as detected by a
change in the amplitude of the HOD peak. The cationic mobilities in
a mixture of tetra-methyl and tetra-ethyl anmonJum chloride in D20
were determined. Application of the technique for studying emulsions
looks prc~lising.
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