Question
the experiment was on Chromatography of kool- aid and I have to answer the discussion questions at the bottom of the page, can you please help me find the answers?
Chromatography of Kool-Aid CHEM 310 objectives: Understand the basic principles behind column chromatography Separate the dyes in Kool-Aid using column chromatograph Understand the relative polarity of the dyes based on their elution. Tools of the Trade: Techniques Sep-Pak C18 Cartridge Reverse-phase chromatography Gradient elution Procedure: Prepare solutions: o 25 mL of each: deionized water, 5% isopropanol (IPA), 25% IPA, 70% IPA (v/v in wate o 0.3 g of grape Kool-aid dissolved in 100 mL DI water solution ski Connect the syringe to the long side of the column To perform separation, push the solution SLowLY through the column using the syringe, always keeping ome amount of liquid above the column Note: never let the column go "dry"! Always keep a layer of mobile phase above the column Equilibrate the column by passing the following solutions: o 10 mL of 70% IPA o 10 mL of water Add the sample by passing re10 mL of the Kool-Aid solution through the column Perform separation by passing the following sequence of solutions o 10 mL of 5% IPA. o 10 mL of 25% IPA Note: more volume may be needed to elute the dyes; record volume used Collect each "fraction" (each syringe-full or when the color change in a separate test tube Record observations "Clean" column by repeating equilibration steps 10 mL of 70% IPA 0 mL of water Discussions Describe how you think the separation is occurring. What is the mechanism of the separation? 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 chromatograph systems consi of a mobile phase and a stationary phase. Define the system what share the stationary phase(s), mobile phase(s sample(s), analyte(s)? 4. Rank each colored component from least polar to most pola Justify your ranking based on the order of elution structures of the dyes. Draw the structures and o Use chemfinder to find the chemica your ranking based on their structures. 5. Many analytical procedures require a separation (chromatography) step prior to the analysis. Why? could easily be modified to be a "quantitative 6. This lab is a "qual ative" lab. ab, 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? Report: Answer the questions in your notebook and turn in via e-mail by the final exam (Wednesday December, 7). In addition to the discussion questions, your notebook wil! be graded as usual. due molecu cs
Explanation / Answer
1. column chromatography is solid liquid chromatographic technique, in which solid is stationary phase and liquid mobile phase and the separtion of sample costituents based on differentail adsorbtion of substance by the adsorbent.
The individual componets are retained by the stationary phase differently and separate from each other while they are running at different speeds through the column with the eluent.
2.In gradient elution eluting strength of solvent increases by changing the composition of solvent mixture through out the experiment. This can improve the separation of components.
3. In the given system stationary phase is column sep-pak c18( non polar ),5%IPA, 70%IPA nad 25%isopropyl alchohol are the mobile phases compositions used in gradient elution, sample is kool aid dissolved in water and analyte is dye in kool aid(which is to be separated or analysed).
4.blue dye has the highest retention factor and most polar , than red dye .The mosr polar elutes first and least polar elutes last.
5.preparation of solvents , eluents must be done carefully inorder to get the effective column separation and to avoid the contamination.dilrect sample can not be taken, we have to check the polarities of both eluting agents and sample solutions as well.
6.by using uv spectrophotometry we can determine the dye qunatitatively
7.if those are colurless, collect the solutions with time intervels, og for TLC, then preparative TLC fro further determinations.
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