Paper Chromatography : Visualizing Agent & Application; Questions and Answers

Paper Chromatography

Visualizing Agent :-

After development of chromatogram the spot should be visualized. It can done by two Method

A. Non specific method

B. Specific method 

A. Non specific method :- where the number of spot can be detected but not the exact nature or type of compound

Example 

1. Iodine chamber method :- where brown or Amber spots are observed when the TLC plates are kept in a tank with few iodine crystal at the bottom.

2. UV chamber for fluorescent compound :- when compound are viewed under UV chamber at 254 nm or at 365 nm fluorescent compound can be detected.

B. Specific method :-

Specific spray reagents or detecting agent or visualising agent are used to find out the nature of compound.

Example

1. Ferric chloride – for phenolic compound and tannins
2. Ninhydrin in Acetone – for amino acids.
3. Dragendroff reagents – for alkaloids

Quantitative Analysis :-

Direct technique :- 

Densitometer is an instrument which measure quantitative the density of the spot. When the optical density of the spot for the standard and test solution are determined,  quantity of the substance can be calculated.

Indirect technique :-

In this technique, the spot are cut into portion and eluted with solvent. This solution  can be analysed by any conventional technique of analysis like spectroflourimeter, electrochemical method etc.

Applications :-

1. Used for identification of drug
2. Identification and separation of Impurities.
3. Used for analysis of mixture of sugar, vitamin, amino acids etc.
4. Analysis of metabolites of drug in blood etc.
5. Identification of foreign substance in drug.

MCQ 

1. In iodine chamber which type of spot is seen ?

A. Blue colour

B. Red colour

C. Brown colour

D. Yellow colour

2.  For phenolic and tannins compound which reagent are used

A. Dragendroff

B. Mayer

C. Ferric chloride

D. Ferric thiocyanate

3. Which is not a indirect visualising method ?

A. Spectroflourimeter

B. Electrochemical

C. A and B

D. Iodine chamber

4.  Which is not application of paper Chromatography ?

A.Used for analysis of mixture of sugar, vitamin, amino acids etc.

B. Analysis of metabolites of drug in blood etc.

C.Identification drug.

D. Used in coating

5. In UV chamber which wavelength are used ?

A. 254 nm

B. 365 nm

C. A and B

D. None of the above

6. Dragendroff reagents are used in reagents of substance

A. Alkaloids

B. Glycoside

C. Tannins

D. All of the above

Answer key

1. C

2. C

3. C

4. D

5. C

6. A

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