Question

please help with instrumental analysis question part a and b. thank you!

6a. In an ion chromatographic separation, what would be the order of retention for the ions Li⁺ (aq),

      Na⁺ (aq), and K⁺ (aq) on a cation exchange resin? Justify your answer.

6b. How can the information you used to answer question 6a above be useful in describing how these

      Ions can be separated using capillary zone electrophoresis? Justify your answer. Remember to

      include the charge on the Inside surface of the capillary column you use as a basis for your answer.

Answer 1

6a. In an ion chromatographic separation, the larger the ion is, the weaker the hold time will be for it, thus for the given cations the order of retention on the column would be,

Li+ (aq) > Na+ (aq) > K+(aq)

As we can see the size increases from Li to K and so the retention time goes down.

6b. Electrophoresis is separation of compoments when a currect is applied. The velocity with which an ion moves depends on the charge and size of the ion. Thus, based on the above results, the cations would interact differently with the charged column surface at a given time. thus when we separate the three cations using the capillary zone electrophoresis method, Li+ will move the slowest, and K+ will move the fastest on the column and come off first. the order of elution thus would be, K+ > Na+ > Li+