Coupling of gradient capillary electrochromatography (gradient CEC) and cap
illary zone electrophoresis (CZE) with nuclear magnetic resonance spectrosc
opy (NMR) was performed using a recently developed capillary NMR interface.
This technique was applied for the analysis of pharmaceuticals and food. A
n analgesic was investigated using isocratic and gradient continuous-flow C
EC-NMR. Comparison of the results demonstrated the superiority of gradient
CEC over isocratic CEC. Aspartame and caffeine, both ingredients of soft be
verages, were separated and analyzed by continuous flow CZE-NMR. The order
of elution could be reversed by altering the pH. This reversal led to an in
creased sample concentration in the NMR detection cell, thus allowing the a
cquisition of a totally correlated spectroscopy (TOCSY) two-dimensional (2-
D) spectrum of the synthetic peptide aspartame.