The caption for Figure 4b (the HPLC separation) should read: 1 = 4-acetamidophenol, 2 = caffeine, 3 = acetylsalicylic acid, 4 = salicylic acid. Secondly, the capacity factor (k') listed in Table 1 for norephedrine is for caffeine, not for norephedrine.
Over the last decade, capillary electrophoresis (CE) has become a widely accepted separation technique. This manuscript describes our efforts to introduce students to capillary zone electrophoresis, the simplest mode of CE, to students in the instrumental analysis course at Bucknell University. The two period laboratory experiment described includes both the use of both HPLC and CZE to determine the formulation of common over the counter analgesic formulations. Typical student data as well as compiled results from the first three years of this experiment are presented. See Correction to this article.
Resolution in channel electrophoresis has been improved by means of the addition of a surfactant to the running buffer and minimization of the channel internal height and sampling capillary internal diameter. Micellar electrokinetic channel chromatography with electrochemical detection has been applied to the separation of several cationic catecholamines and has been used to continuously monitor a dynamic system of dopamine, norepinephrine, and epinephrine. Resolution was also enhanced by coupling small internal-diameter (5 microm) sampling capillaries with sub-micrometer internal-height separation channels. The improvements in resolution offered by these methods will extend the applicability of channel electrophoresis with electrochemical detection to more complex samples while permitting sample volumes in the nL range to be probed.
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