PAPER CHROMATOGRAPHYPAPER CHROMATOGRAPHY   SUBMITTED TO SUBMITTED TO   Dr.K.M.LOKANATH RAI.sir        Dr.P.NAGARAJ.sirDr.K.M.LOKANATH RAI.sir        Dr.P.NAGARAJ.sir Dept.Of Chemistry                           Dept,Of Chemistry Manasagangothri                             Manasagangothri   SUBMITTED BYSUBMITTED BY CHANDRAKANTHA.K.SCHANDRAKANTHA.K.S 2nd YEAR M.TECH.

CHROMATOGRAPHY

  Chromatography  (from  Greek  :chroma,  colour and "grafein"  to write)  is  the  collective  term  for  a family of laboratory techniques for the separation of mixtures. It  involves passing a mixture dissolved in a "mobile phase" through a stationary phase, which separates  the  analyte  to  be  measured  from  other molecules in the mixture and allows it to be isolated.

  Chromatography  may  be  preparative  or analytical.  Preparative  chromatography  seeks  to separate  the  components  of  a  mixture  for  further use (and is thus a form of purification). 

Mikhail Semyonovich Tsvet invented the first chromatographic technique in 1900 during his research on 

chlorophyll. He used a liquid-adsorption column containing calcium carbonate to separate plant pigments. 

  In  1952  Archer  John  Porter  Martin  and  Richard Laurence Millington  Synge were  awarded  the Chemistry Nobel  Prize  for  their  invention  of  partition chromatography. Since then, the technology has advanced rapidly. This  technique  is  a  type  of  partition  chromatography developed  by  CONSDEN,GORDEN,MARTAIN  AND SRINGE IN ENGLAND IN 1944.

History

Is a technique used to separate and identify the components of a mixture.

Works by allowing the molecules present in the mixture to distribute themselves

between a stationary and a mobile medium.

Molecules that spend most of their time in the mobile phase are carried along faster.

Chromatography is a technique for separating mixtures into their components in order to analyze, identify, purify, and/or quantify the mixture or components.

Separate

• Analyze

• Identify

• Purify

• QuantifyComponentsMixture

Chromatography is used by scientists to:

• Analyze – examine a mixture, its components, and their relations to one another

• Identify – determine the identity of a mixture or components based on known components

• Purify – separate components in order to isolate one of interest for further study

• Quantify – determine the amount of the a mixture and/or the components present in the sample

Mixture

(Ink)

ComponentsSeparation

Stationary Phase

(filter paper)

Mobile Phase

(water)

On the basis of techniques employed in paper chromatography, it may be classified into 5 types.

Ascending paper chromatography

Descending paper chromatography

Ascending and descending paper chromatograpy

Radial or circular paper chromatography Two dimentional paper chromatography

Ascending paper chromatography: In this technique, the paper is supported vertically in a closed glass tank or tube. The lower edge of the filter paper sheet is dipped in suitable solvent known as eluting agent or developing agent. The mixture of components to be separated in solvent is spotted on filter paper strip. Since the lower end is dipped in solvent, the solvent rises up due to capillary action. Different ingredients of the mixture travel through different heights.

Descending paper chromatography: In this technique, the eluting agent is kept in a narrow trough near the top of the container. The upper end of the paper dips in it. In such case, the solvent move downwards. Then it is termed as descending paper chromatography. Descending chromatography is generally faster than the ascending method, but at the expense of a slight increase in complexicity of technique.

Ascending paper chromatography:

Ascending P.C

Descending P.CDescending P.C

3. Ascending - Descending Chromatography: It is a hybrid of two techniques. The upper part of ascending chromatography can be folded over a glass rod allowing the descending development to change over into the descending after crossing the glass rod.

Radial or circular paper chromatography: In this technique, a circular piece of paper having a wick or tongue (of width of about 2 mm) cut parallel to the radius from edge of the centre is required. The mixture to be analysed is deposited as a spot at the centre of the paper which is upper end of the wick or tongue. After drying the spot, the paper is horizontally fixed on the petridish having the solvent so that the tongue of the paper dips into the solvent. The solvent flows through the tongue tough the paper. When the solvent front has moved through a sufficient large distance, the various components of the mixture are separated in the form of concentric circular zones or bands.

5. Two dimensional chromatography: In this a square rectangular paper is used. The sample applied on one of the corners. The second development is performed at right angle of the direction of first run. This type of chromatography can be carried out with identical solvent system in both directions or by two solvent systems

Sl.No Solvents used1 Isopropanol – ammonia - water (9 : 1 : 2)2 n-butanol - acetic acid – water (4 : 1 : 5)3 Water - phenol4 Formaldehyde - chloroform5 Formamide – chloroform - benzene6 Formamide - benzene7 Formamide – benzene - cyclohexane8 Dimethyl formamide – cyclohexane9 Kerosene - 70% isopropanol10 Paraffin oil – dimethyl formamide – methanol -

water

Common solvents used in paper chromatography

are as follows.

Common solvents used in paper chromatography

are as follows.

In the animation below the red molecules are more soluble in the liquid (or less volatile) than are the green molecules.

Retention The retention is a measure of the speed at which a substance moves in a chromatographic system. Retention is measured as the retention factor Rf, the run length of the compound divided by the run length of the eluent front:

The retention of a compound often differs considerably between experiments due to variations of the eluent, the stationary phase, temperature, sample matrix and the setup.

Retention The retention is a measure of the speed at which a substance moves in a chromatographic system. Retention is measured as the retention factor Rf, the run length of the compound divided by the run length of the eluent front:

The retention of a compound often differs considerably between experiments due to variations of the eluent, the stationary phase, temperature, sample matrix and the setup.

Rf = Distance moved by the compoundDistance moved by the solvent

ADVANTAGESIt can be used to determine the number of compounds in mixtureIt can be used to identify the specific compoundsIt can be used to monitor the process of reactionTLC has largely replaced by the paper chromatography

Several advantagesRun fasterBetter separationCan tolerate stronger solventsCan choose between different stationary phases

ConclusionsPaper chromatography one of the technique of

considerable importance.,but this is nolonger the case. still useful as an aid to teaching

chromatography in schools and colleges, there arevirtually no situations where separations originally

developed for paper chromatographic methods cannotnow be performed faster and better by TLC.

REFERECE

Modern Analytical ChemistryDavid HarveyDePauw University

Analytical chemistry - prof. dash