Chromatography and Its Types

CHROMATOGRAPY & ITS
TYPES
Dr. Shabana Naz Shah
PhD. in Pharmaceutical Chemistry
Sr. Manager Technical Services
Martin Dow Limited
1

CHROMATOGRAPHY
 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.
 Chroma -"color" and graphein - "to write”.
 Colour bands - separation of individual compounds 2

HISTORY
Chromatography
(from Greek :chromatos -- color , "graphein" -- to write)
 1903 Tswett - plant pigments separated on chalk columns
 1931 Lederer & Kuhn - LC of carotenoids
 1938 TLC and ion exchange
 1950 Reverse phase LC
 1954 Martin & Synge (Nobel Prize)
 1959 Gel permeation
 1965 instrumental LC (Waters)
3

PURPOSE OF CHROMATOGRAPHY
 • Analytical
Determine Chemical composition of a sample
• Preparative
Used to purify sufficient quantities of a substance
4

CHROMATOGRAPHY TERMS
 Chromatograph - equipment that enables a sophisticated
separation EX. Gas chromatography or Liquid chromatography
 Eluent - Fluid entering column/ solvent that carries the
analyte.
 Eluate - Mobile phase leaving the column.
 Stationary phase - Immobilized phase
 Immobilized on the support particles or on the inner wall of the
column tubing.
 Examples : Silica layer - Thin Layer Chromatography
5

CHROMATOGRAPHY TERMS
 Mobile phase - Moves in a definite direction. Liquid (LC),
Gas (GC). The mobile phase moves through the
chromatography column (the stationary phase) where the
sample interacts with the stationary phase and is separated.
 Retention time: Time takes for a particular analyte to pass
through the system (from the column inlet to the detector)
under set conditions.
 Sample (Analyte) :Substance analyzed in chromatography.
 Solvent: Any substance capable of solubilizing another
substance.
6

CHROMATOGRAM
 Visual output of the chromatograph.
 Separation - Different peaks or patterns on the
chromatogram correspond to different components
of the separated mixture.
7

HOW TO DESCRIBE A CHROMATOGRAM
 Chromatogram – Response of a detector vs time.
Shows when various components come off a column.
 Retention time (t1) – The time at which a component
elutes from a column.
 Theoretical Plates:
Assume a chromatographic peak has a Gaussian shape
H is height of peak W1/2 is with at ½ Height
(If true Gaussian W1/2 = 2.35
Where  = standard deviation)
Width at baseline should be 4 
9

HOW TO DESCRIBE A CHROMATOGRAM
 For chromatography we retain the name Theoretical
Plate, but calculate it using the retention time and the
width at ½ height.
N = 555tr
2
W1/2
2
 N is number of Theoretical Plate. Again the bigger the N
the better, because that means the width of the peak is
small compared to its retention time.
10

PRICNIPLES OF CHROMATOGRAPGHY
 Physical method of separation that distributes
components to separate between two phases
moves in a definite direction.
 Substances are separated based on their
differential distribution between two phases.
 Substances will move with the mobile phase at
different rate depending upon their Partition or
Distribution co- efficients.
11

12

13

FACTORS AFFECTING THE SEPARATION
14
Intermolecular interaction between the two
phases.
Extent of dispersion of solute molecules over the
stationary phase.

USES FOR CHROMATOGRAPHY
 Real-life examples of uses for chromatography:
• Pharmaceutical Company – determine amount of
each chemical found in new product
• Hospital – detect blood or alcohol levels in a patient’s
blood stream
• Law Enforcement – to compare a sample found at a
crime scene to samples from suspects
• Environmental Agency – determine the level of
pollutants in the water supply
• Manufacturing Plant – to purify a chemical needed to
make a product 15

CLASSIFICATION OF CHROMATOGRAPHY
16
There are two classification schemes:
Mobile phase
Attractive forces

17
Mobile Phase:
Gas (GC)
Water (LC)
Organic solvent (LC)
Supercritical fluid (SCFC)

CLASSIFICATION BASED ON MOBILE PHASE
18

CLASSIFICATION BASED ON ATTRACTIVE FORCES
19
1. Adsorption
2. Ion Exchange
3. Partition
4. Size Exclusion

20
Techniques by Chromatographic bed shape.
Column chromatography
Planar chromatography
Paper chromatography
Thin layer chromatography
Techniques by Physical state of mobile phase.
Gas chromatography
Liquid chromatography
Affinity chromatography
Supercritical fluid chromatography

COLUMN CHROMATOGRAPHY
21
Column chromatography involves the following:
1. Adsorption/retention of substance on stationary phase
2. Separation of adsorbed substance using mobile phase.
3. Recovery of individual components by continuous flow of
mobile phase.
4. Quantitative and qualitative analysis of solute and the
components which are recovered.

24
Separation technique - Stationary phase is present as or on a
plane.
Paper – Paper Chromatography.
Layer of solid particles spread on a support such as a glass
plate - Thin layer Chromatography.
Different compounds in the sample mixture travel different
distances according to how strongly they interact with the
stationary phase as compared to the mobile phase.
Retention factor (Rf).
PLANAR CHROMATOGRAPHY

25
PAPER CHROMATOGRAPHY
PRINCIPLE:
This paper is made of cellulose, a polar substance, and the compounds
within the mixture travel farther if they are non- polar.
More polar substances bond with the cellulose paper more quickly, and
therefore do not travel as far.
• Retention factor :
Rƒ = zero, - Solute remains in the stationary phase and thus it is immobile.
Rƒ = 1 - Solute has no affinity for the stationary phase and travels with the
solvent front.

27
THIN LAYER CHROMATOGRAPHY
Widely employed laboratory technique.
Stationary phase - Adsorbent - Silica gel, Alumina, Cellulose.
Widely used in pharmaceutical & food stuff industry
Advantages :
 Simple, Rapid and Cheap
 Faster runs.
 Better separations.
 Choice between different adsorbents.
 Better resolution
 Allow for quantification

28
THIN LAYER CHROMATOGRAPHY
Used to identify the unknown compounds and to determine the
purity of mixture.
TLC Plate - Aluminium or glass - coated by stationary phase.
Coated material : 0.1-0.3mm in thickness.
Fluorescent indicator that will make it florescence during the
UV light exposure.
STATIONARY PHASE: Silica gel, Alumina, or Cellulose on a
flat, inert substrate.
MOBILE PHASE: Volatile Organic solvents

30
GAS CHROMATOGRAPHY
Gas-Liquid chromatography, (GLC).
Mobile phase – Gas (Helium) Carrier Gas Pressure = 4 kg/cm2
Stationary phase - Column, which is typically "packed" or
"capillary".
The stationary phase is adhered to the inside of a small-
diameter glass tube (a capillary column) or a solid matrix inside a
larger metal tube (a packed column).
Partition Coefficient of Volatile analyte between a solid
stationary phase (Silicone) and a mobile gas (Helium).

31
GAS CHROMATOGRAPHY
Advantages:
High sensitivity.
High Resolution.
High speed.
High Accuracy.
Highly Quantitative.
APPARATUS:
Gas Chromatograph, GC analyzer, Normal syringes and one micro
syringe, Beakers, Sample bottles and Electronic weight.
CHEMICALS:
Methanol, Isopropyl Alcohol and water.
SAMPLE:
Gases, Liquid, Solids.
M. Wt: 2-800.
Volatile.

33
APPLICATION OF GAS CHROMATOGRAPHY
Quantitative & Qualitative analysis of low polarity
compounds.
Analytical chemistry, Biochemistry, Petrochemical,
Environmental monitoring.
Measure picomoles of a substance in a 1 ml liquid sample,
or parts-per-billion concentrations in gaseous samples.
Measuring toxic substances in soil, air or water.

34
APPLICATION OF GC- MS
Environmental Monitoring : Organic Pollutants.
Criminal Forensics : Analyze the particles (Fiber) from a
human body in order to help link a criminal to a crime.
Law Enforcement : Detection of illegal narcotics.
Forensic Toxicology : Find drugs and/or poisons in
biological specimens of suspects, victims, or the deceased.
Sports Anti-doping Analysis : Test athletes urine samples.
Security : Explosive detection (September 11 development)
systems have become a part of all US airports.
Food, Beverage and Perfume : from spoilage or
Adulteration - aromatic compounds, esters, fatty acids,
alcohols, Aldehydes, terpenes
Medicine : Congenital metabolic diseases In Born error of
metabolism

LIQUID CHROMATOGRAPHY
35
 Mobile phase - Liquid.
 Column or a plane.
 Very small packing
particles and a relatively
high pressure - High
Performance Liquid
Chromatography (HPLC).

PRINCIPLE LIQUID CHROMATOGRAPHY

SOLVENT TYPES USED IN LIQUID
CHROMATOGRAPHY
37
 ORGANIC
 Methanol
Acetonitrile
THF
Methylene Chloride
Hexane
 AQUEOUS
Water
SOLVENT MIXTURES
CHCl3 / ETOH
MeOH / H2O
MeOH / CAN /H2O
Hexane / IPA

 Mass spectra is obtained
rapidly.
 Small amount of material is
required to form the
spectra.
 Data collected is highly
informative with respect to
molecular structure.
38
LC- MS

 Pharmacokinetics : How quickly a drug will be
cleared from the hepatic blood flow and organs of the
body.
 Proteomics : Peptide mass fingerprinting.
 Drug development: Peptide Mapping, Glycoprotein
Mapping, Natural Products Dereplication, Bioaffinity
Screening, In Vivo Drug Screening, Metabolic Stability
Screening, Metabolite Identification, Impurity
Identification, Degradant Identification, Quantitative
Bioanalysis, and Quality Control.
 Fungal toxins.
 Pesticides, Herbicides.
39
APPLICATION OF LC- MS

 Columns : Small diameter (4.6 mm), stainless steel, glass or
titanium.
 Column packing with very small (3, 5 and 10 μm) particles.
 Relatively high inlet pressures and controlled flow of the mobile
phase.
 Detecting very small amounts
 High resolution.
 Rapid analysis.
 Speed, efficiency, sensitivity and ease of operation.
 High degree of versatility.
 Easily separate a wide variety of chemical mixtures.
 400 atmospheres.
PUMP PRESSURE:
 "Ultra High Performance Liquid Chromatography" systems 1000
atmospheres.)
40
HIGH PERFORMANCE LIQUID
CHROMATOGRAPHY

42
ELUTION OF HPLC SYSTEM
Isocratic and Gradient.
ISOCRATIC :
ISO = SAME
Solvent Composition Stays the Same for the
Entire Run Example : 60:40 (Alcohol:Water)
GRADIENT:
Solvent Composition Changes Throughout the
Run

 Nature of the stationary phase
 Separation process
 Adsorption chromatography
 Ion-exchange chromatography
 Size exclusion chromatography
43
TYPES OF HPLC

 Adsorption chromatography is probably one of the
oldest types of chromatography around.
 It utilizes a mobile liquid or gaseous phase that is
adsorbed onto the surface of a stationary solid phase.
The equilibration between the mobile and stationary
phase accounts for the separation of different solutes.
44
ADSORPTION CHROMATOGRAPHY

 In this type of chromatography, the use of a resin
(the stationary solid phase) is used to covalently
attach anions or cations onto it.
 Solute ions of the opposite charge in the mobile
liquid phase are attracted to the resin by
electrostatic forces.
45
ION EXCHANGE CHROMATOGRAPHY

 Gel filtration or gel permeation chromatography.
 Separation-Molecular size of its components.
 Larger molecules are rapidly washed through the column,
smaller molecules penetrate inside the porous of the packing
particles and elute later.
46
SIZE EXCLUSION CHROMATOGRAPHY

 Based on specific & non-covalent binding of the proteins to
other molecules-Ligand.
 Physical properties of the analyte.
 Biochemistry in the purification of proteins bound to tags.
 After purification, some of these tags are usually removed and
the pure protein in obtained.
47
AFFINITY CHROMATOGRAPHY

 Used for the analysis and purification of low to moderate molecular
weight, thermally labile molecules.
 Principles are similar to those of HPLC.
 Mobile phase – High pressure liquid or super critical Carbon
dioxide.
 Modifiers – Methanol, ethanol, isopropyl alcohol, acetonitrile and
chloroform.
 Application- Use in industry primarily for separation of Chiral
(Asymmetric Carbon atoms) molecules likes serine, soman,
glyceraldehydes, phosphorus, sulfar metal, cobalt, etc.
48
SUPERCRITICAL FLUID CHROMATOGRAPHY

PARTITION CHROMATOGRAPHY
 This form of chromatography is based on a thin
film formed on the surface of a solid support by a
liquid stationary phase. Solute equilibriates
between the mobile phase and the stationary
liquid.
49

MOLECULAR EXCLUSION CHROMATOGRAPHY
 Also known as gel permeation or gel filtration, this type of
chromatography lacks an attractive interaction between the stationary
phase and solute.
 The liquid or gaseous phase passes through a porous gel which
separates the molecules according to its size.
 The pores are normally small and exclude the larger solute
molecules, but allows smaller molecules to enter the gel, causing
them to flow through a larger volume.
 This causes the larger molecules to pass through the column at a
faster rate than the smaller ones.
50

Chromatography and Its Types

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