PULSED FIELD GRADIENT NMR-STUDY OF PROBE MOTION IN POLYACRYLAMIDE GELS

Probe diffusion and electrophoresis in polyacrylamide (PA) gels have been studied by means of pulsed field gradient (PFG) NMR methods. The probes were HDO, tetramethylammonium ion, N,N,N',N'-tetramethylethylenediamine, and tetrahexylammonium ion. Reduced tracer diffusion coefficients of the probes are well correlated by D/D0 = exp(-3.2R(h)0.53C), where D and D0 are the probe tracer diffusion coefficients in the presence and absence of the gel, respectively, R(h) (angstrom) is the hydrodynamic radius of the probe, and C (g/mL) is the PA concentration. The electrophoretic mobility of the tetramethylammonium ion scales with gel concentration in the same fashion. These results support the conclusion of Park et al.7 that R(h)C/xi, where xi is the mesh size, is a useful scaling parameter.