Question

Talking about Chromatography using kool aid, 70% isopropanol, 25% isopropanol and 5% isopropanol what is the answer to the questions?

1. Describe h0w you think the separation is occurring. What is the mechanism of the separation?

2. Why do you think the consistency of the solution added to the column was changed throughout the separation? This process is called gradient elution.

3. All chromatography systems consist of a mobile phase and a stationary phase. Define the system: what is/are the stationary phase(s), mobile phase(s), sample(s), analyte(s)?

4. Rank each colored component from least polar to most polar. Justify your ranking based on the order of elution.

Use chemfinder to find the chemical structures of the dyes. Draw the structures and justify your ranking based on their structures.

5. Many analytical procedures require a separation (chromatography) step prior to the analysis. Why?

6. This lab is a “qualitative” lab. It could easily be modified to be a “quantitative” lab. Briefly describe how you could make this a quantitative lab, i.e., how could you determine the concentration of the dyes in the Kool-Aid sample?

7. Compounds need not be colored to be analyzed using chromatography. How could colorless compounds be detected in a chromatography system?

Answer 1

1.This can be done by column chromatography, in which separation of sample constituents is based on differential adsobtion of substance by adsorbent.

2.study change in the composition of mobile phase during the chromatographic run is caleed gradient elution.

3.the analyte in this given experiment is dye in kool aid, it is nonpolar so the mobile phase is polar. the gievn 75%, 25% and 5% isopropanal is the composition of mobile phase.In chromatography the mobile ( gas or liquid) is alwasys moving and the stationary phase is rigid( eitheir solid( silica gel, alumina) or semi solid).

4.most polar elutes first and least polar elutes last.,the most polar molecules are strongly attracted to polar mobile phase.

5. we have to set the solvent mixture, prepare the analyte solution and prepare eluting agent befor going to the experiment.

6.by collecting eluting mixture with measuring the time intervals(if it is colourless) and applying TLC, or by uisng spectrophotometry(if it is coloured) ,we can determine the analyte quantitatively.