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Method Set-Up for a Chemical Separation

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Suggest a buffer and mobile phase composition to get the best separation given:
1. HPLC instrument
2. C18 reverse phase column
3. 1mM solution of each of the following compounds in Methanol
4. Mobile phase is methanol-buffer mixture

Compounds are 3 seperate groups:
1. Carboxylic Acids:
a. Benzoic acid
b. Phthalic acid
c. Toluic acid

2. Amino:
a. aniline
b. 4-aminotoluene
c. orhto-pheylenediamine

3.Amino Carboylic Acids:
a. 4-aminobenzoic acid
b. 2-aminobenzoic acid
c.4-amino-2-methylbenzoic acid

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Solution Preview

To answer this interesting question, I think you will need to remember how the chromatography process works. I think it is desirable to have the solute particles to have some time on the column and some time in the mobile phase.

Since you are using a reversed phase column, the mobile phase will be ...

Solution Summary

The methods set-up for a chemical separation are discussed. The solution is 225 words. The reverse phase columns are given.

See Also This Related BrainMass Solution

Resolution of Mixtures: Filtration and Distillation

The experiment performed is outlined in the attached pdf file. I did not do the melting point or silver nitrate parts, but I would still like to know what was going on if I did. Please help me with citations as needed, so I can look them up for more detail.

Purpose: The separation of mixtures into their constituent components defines an entire sub-field of chemistry referred to as separation science. In this experiment, the purpose was to perform techniques for the resolution of mixtures of solids and liquids.

A few questions:
1. This experiment examines the techniques of re-crystallization of solids, and also the techniques of simple and fractional distillation of liquids, as examples of methods by which mixtures are resolved into their components. Find three additional methods by which mixtures may be resolved, and describe the techniques briefly, including the sorts of mixtures to which the techniques are applied.

2. Why is a fractioning column packed with small glass beads or short pieces of glass tubing? How does this help improve distillation?

3. Some mixtures of volatile liquids cannot be completely separated by fractional distillation because of the formation of what are called azeotropes among the liquids. What is the definition of an azeotrope (please provide a reference)?

4. Why would the flask containing a mixture to be distilled never be heated to complete dryness?

5. A simple test using silver nitrate is used to detect whether or not a chloride ion is present in the distillate in this experiment. Write the complete balanced chemical equation for the reaction between silver nitrate and sodium chloride.

6. How do simple and fractional distillation differ? Under what circumstances is one method likely to be used in preference to the other method?

7. In spite of such a major portion of the earth's surface being covered by water, surprisingly little use has been made of the distillation of seawater as a source of drinking water in arid areas. Why do you suppose this is so?

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