Question

When the following three compounds are separated by micellar electrokinetic chromatography at, three peaks are observed. When 10mM$\mathbf{v}\mathbf{}\mathbf{\alpha }\mathbf{-}\mathbf{cyclodextrin}$is added to the run buffer, two of the three peaks split into two peaks, giving a total of five peaks. Explain this observation and predict which compound does not split.

Short answer

Cyclobarbital and Thiopental will generate two peaks whereas phenobarbital would have one peak.

Step-by-step solution

Definition of electrokinetic chromatography

Micellar electrokinetic chromatography (MEKC) is a chromatography technique used in analytical chemistry. It used for separating neutral molecules and ions.

Explanation of observation

Among the three compounds, cyclobarbital and thiopental have one chiral carbon, whereas phenobarbital is achiral. Both cyclobarbital and thiopental form non-superimposable mirror images known as enantiomers.

The enantiomers will spend different time interacting with cyclodextrin as they migrate through the capillary. This will lead to splitting of the peaks cyclobarbital and thiopental into two separate peaks resulting in a total of five peaks. The chiral centres for cyclobarbital and thiopental are marked with an asterisk.