chromatography new

49
CHROMATOGRA PHY

Upload: jamaica-tapiculin

Post on 28-Aug-2014

1.905 views

Category:

Technology


6 download

DESCRIPTION

 

TRANSCRIPT

Page 1: Chromatography new

CHROMATOGRAPHY

Page 2: Chromatography new

CHROMATOGRAPHY

A laboratory technique in which the components of a sample are separated based on how they distribute between two chemical or physical phases, one of which is stationary and other of which is allowed to travel through the separation system.

Page 3: Chromatography new

CHROMATOGRAPHY

Introduced first by the Russian botanist Mikhail Semenovich Tswett.

Mixtures of solutes dissolved in a common solvent are separated from one another by a differential distribution of the solutes between two phases.

Page 4: Chromatography new

PRINCIPLE

Fractionalism of mixtures of substances

In the operation of the chromatogram, a mobile gaseous or liquid phase is use to wash the substances to be separated through a column of a porous material.

Page 5: Chromatography new

PRINCIPLE

The rate of migration of the solute depends upon the rate of interaction of the solute with the two phases, one being the mobile phases and the other stationary phase as the compounds travel through the supporting medium.

Page 6: Chromatography new

DEFINITION OF TERMS:

Capillary Action – the movement of liquid within the spaces of a material due to the forces of adhesion, cohesion, and surface tension.

Retention time Peak Viscosity

Page 7: Chromatography new

DEFINITION OF TERMS:

VOCs Stationary phase Mobile phase

Page 8: Chromatography new

COMPONENTS OF A CHROMATOGRAPH

MOBILE PHASE – A phase that is flowing through the column and causes sample components to move toward the column’s end.

STATIONARY PHASE- A fixed phase that is coated or bonded within the column; it always remain in the system.

It is responsible for delaying the movement of compounds as they travel through the column.

SUPPORT- onto which the SP is coated or attached.

Page 9: Chromatography new

COMPONENTS OF A CHROMATOGRAPH

Receiving vessel

COLUMNORIGINAL SAMPLE AND MOBILE PHASE

SUPPORT AND STATIONARY PHASE

Page 10: Chromatography new

TYPES OF CHROMATOGRAPHY

CAN BE CLASSIFIED ACCORDING TO:

∞MOBILE PHASE∞STATIONARY PHASE∞SUPPORT

Page 11: Chromatography new

GAS CHROMATOGRAPHY

A type of Chromatography in which the mobile phase is a GAS.

First GC system was developed by Erika Cremer

The presence of a gas mobile phase makes GC valuable for separating substances like VOCs that occur naturally as gases that can easily be placed into gaseous phase.

Page 12: Chromatography new

GAS CHROMATOGRAPHY

• It can separate nanograms or pictograms of volatile substances.

• It is principally a method for the separation and quantitative determination of gases and volatile liquids and substances.

Page 13: Chromatography new

GAS CHROMATOGRAPHY

HOW IS IT PERFORMED? A System called Gas Chromatograph

is used to perform GC.COMPONENTS:

GAS SOURCEINJECTION SYSTEMCOLUMNDETECTOR

Page 14: Chromatography new
Page 15: Chromatography new

GAS CHROMATOGRAPHY∞GAS SOURCE- supplies the mobile

phase. It is typically a gas cylinder equipped with pressure regulators to deliver the mobile phase at a controlled state.

∞ INJECTION SYSTEM- consists of a heated loop or port into which the sample is placed and converted into a gaseous form.

Page 16: Chromatography new

GAS CHROMATOGRAPHY∞COLUMN- contains the stationary

phase and support material for the separation of components in the sample. This column is held in an enclosed area known as the column oven.

∞COLUMN OVEN- maintains the temperature at a well-defined value.

∞DETECTOR- monitors sample components as they leave the column.

Page 17: Chromatography new

GAS CHROMATOGRAPHYFACTORS THAT AFFECT GC:

Requirements for the AnalyteVolatility and Thermal StabilityChemical Derivatization

Page 18: Chromatography new

GAS CHROMATOGRAPHYCommon Mobile Phases in GC: Hydrogen Helium Nitrogen Argon

Page 19: Chromatography new

GAS CHROMATOGRAPHYGC SUPPORT MATERIALS

Packed Columnfilled with small support particles that

acts as an adsorbent or that are coated with the desired stationary phase.

Open- Tubular Columnsstationary phase coated on or attached

to its interior surface.

Page 20: Chromatography new

GAS CHROMATOGRAPHYGC STATIONARY PHASES

Gas- Solid Chromatography ( solid adsorbents)

Gas-Liquid Chromatography (liquids coated on solids)

Bonded phases

Page 21: Chromatography new

GAS CHROMATOGRAPHY◊ Gas-Solid Chromatography

o Solid adsorbent is used as a stationary phase.o Uses the same material as both the support

and stationary phase, with retention occurring through the adsorption of analytes to the support’s surface.

o Example of support is a MOLECULAR SIEVE.o Other supports include:

oORGANIC POLYMERS - porous polystyreneo INORGANIC SUBSTANCES – Silica or

Alumina

Page 22: Chromatography new

GAS CHROMATOGRAPHY

o Increasing the surface area of the GSC support will increase the phase ratio and result in higher retention for analytes

o Pore size is important because only compounds smaller than the pores are able to contact the surface are within the space.

o Polarity of Support and its functional groups will also affect how analytes will bind to them.

Page 23: Chromatography new

GAS CHROMATOGRAPHY◊ Gas-Liquid Chromatography

o A chemical coating or layer is placed onto the support and used as the stationary phase.

o Most Common types of GC.

o 100% dimethylpolysiloxane, 5%phenyl-95% methyl polysiloxane – Examples of liquids that are used as Stationary phase.

Page 24: Chromatography new

GAS CHROMATOGRAPHY◊ Gas-Liquid Chromatography

o All of these liquids have High boiling points and low volatilities, which allows them to stay within the column at relatively high temperatures that are often used in GC for sample injection and elution.

o Liquids are also wettable- easy to place onto a support in a thin, uniform layer.

Page 25: Chromatography new

GAS CHROMATOGRAPHY◊ Gas-Liquid Chromatography

o All of these liquids have High boiling points and low volatilities, which allows them to stay within the column at relatively high temperatures that are often used in GC for sample injection and elution.

o Liquids are also wettable- easy to place onto a support in a thin, uniform layer.

Page 26: Chromatography new

GAS CHROMATOGRAPHY◊ Bonded Phases

o Column Bleed- most nonvolatile liquid will slowly vaporize or break apart and leave the column over time.

o Column bleed changes the retention characteristics of the column.

o It can also cause some GC detectors to have a high background and noisy signal as the stationary phase leaves the column and enters the detector.

o Use of bonded phase minimize column bleed.

Page 27: Chromatography new

GAS CHROMATOGRAPHY◊ Bonded Phases

o Produced by reacting groups on a polysiloxane stationary phase with silanol groups that are located on the surface of a silica support.

Page 28: Chromatography new

GAS CHROMATOGRAPHYTypes of Gas Chromatography Detectors General Detectors

x Thermal Conductivity Detector-used for both organic and inorganic

compounds-measures the ability of the eluting

carrier gas and analyte mixture to conduct heat away from hot-wire filament-”thermal conductivity”.-example: Wheatstone bridge

Page 29: Chromatography new

GAS CHROMATOGRAPHY Flame Ionization Detector

- detects organic compounds by measuring their ability to produce ions when they are burned in flame.

Page 30: Chromatography new

GAS CHROMATOGRAPHY Selective Detectors

x Nitrogen-Phosphorous Detector - selective for the determination of nitrogen- or phosphorous containing compounds. - Similar to FID, but does not use a flame for ion production.

Page 31: Chromatography new

GAS CHROMATOGRAPHY Electron capture detector

- detects compounds that have electronegative atoms or groups in their structure, such as halogen atoms ( I,Br,Cl and F) and Nitro Groups.

-can also be used to detect polynuclear aromatic compounds, anhydrides and conjugated carbonyl compounds.

Page 32: Chromatography new

GAS CHROMATOGRAPHYApplications: Most effectively used for analyses of

organic compounds, space related, complex mixtures of volatile substances at column temperature of less than -40 °C to greater than 550° C.

Geochemical research projects such as determination of various environmental pollutants at extremely low concentrations.

Page 33: Chromatography new

GAS CHROMATOGRAPHY

ADVANTAGES:o Ability to provide

qualitative information and quantitative information

o FAST ANALYSISo Efficient, providing high

resolutiono Sensitiveo Nondestructiveo Requires small sampleso Inexpensive

DISADVANTAGES:o LIMITED to volatile

sampleso Not suitable for

thermally labile samples

o Fairly difficult for large preparative samples

o Requires spectroscopy usually mass spectroscopy for confirmation of peak identity

Page 34: Chromatography new

LIQUID CHROMATOGRAPHY√ A Chromatographic technique in which

the mobile phase is a liquid.√ Originally developed by Russian

botanist Mikhail Tswett in 1903.√ Its popularity is due to the ability of this

method to work directly with liquid samples, which makes it valuable in such areas as food testing, environmental testing and biotechnology.

Page 35: Chromatography new

LIQUID CHROMATOGRAPHYHOW IS LIQUID CHROMATOGRAPHY

PERFORMED? A System known as a Liquid

Chromatograph is used to perform LC.

Page 36: Chromatography new

LIQUID CHROMATOGRAPHY√ Components of the LC System:

Support – enclosed in a Column Stationary phase- enclosed in a Column Liquid mobile phase-delivered to Column by

means of Pump Injection device- on analytical applications it

is being used,to apply samples to the column.

Collection Device (optional)- placed after the column to capture analytes as they elute.

Page 37: Chromatography new
Page 38: Chromatography new

LIQUID CHROMATOGRAPHYFACTORS THAT AFFECT LIQUID CHROMATOGRAPHY:

*requires both a difference in retention and good efficiency for it to separate two given chemicals*Sample*Analyte Requirements*Formats*Role played by the Mobile phase

Page 39: Chromatography new

LIQUID CHROMATOGRAPHYRequirements for the Analyte:Must be possible to place this

chemical into a liquid that can be injected onto the column.

There must be a difference in retention between the analytes to be prepared.

Page 40: Chromatography new

LIQUID CHROMATOGRAPHYTypes of Liquid Chromatography: Adsorption Chromatography Partition Chromatography Ion-Exchange Chromatography Size-Exclusion Chromatography Affinity Chromatography

Page 41: Chromatography new

LIQUID CHROMATOGRAPHY1. ADSORPTION CHROMATOGRAPHY

A chromatographic technique that separates solutes based on their adsorption to the surface of a support. Also known as Liquid-Solid Chromatography Equivalent method in GC is Gas-Solid

Chromatography Uses the same material as both stationary

phase and support. Retention process can be explained on the ff

below: A+ n M-Surface A-Surface + n M

Page 42: Chromatography new

LIQUID CHROMATOGRAPHY Elutropic strength- strength of a

mobile phase in adsorption chromatography It is a measure of how strongly a

particular solvent or liquid mixture will absorb to the surface of a given support.

Examples: silica and Alumina supports A liquid with large elutropic strength will

strongly adsorb to the given support, which will prevent the analyte from binding to the support.

Page 43: Chromatography new

LIQUID CHROMATOGRAPHY

Page 44: Chromatography new

LIQUID CHROMATOGRAPHY

Page 45: Chromatography new

LIQUID CHROMATOGRAPHY2. PARTITION CHROMATOGRAPHYo It is a Liquid Chromatographic

technique in which solutes are separated based on their partitioning between a liquid mobile phase and a stationary phase coated on a solid support.

o Support used is usually Silicao Originally, it involves coating of support

with a liquid stationary phase that was immiscible with the mobile phase

Page 46: Chromatography new

LIQUID CHROMATOGRAPHYTwo Main Categories of Partition Chromatography:• Normal-phase- uses polar stationary

phase

• Reversed phase-uses nonpolar stationary phase

Page 47: Chromatography new

LIQUID CHROMATOGRAPHYApplications: Used in analytical laboratories Use of NPLC for separating analytes in

organic solvents and chemicals that contain polar functional groups.

Page 48: Chromatography new

LIQUID CHROMATOGRAPHY3. ION- EXCHANGE CHROMATOGRAPHYSolutes are separated by their adsorption onto a support containing fixed charges on its surface. Routinely used in Industry for the

removal or replacement of Ions in products.

Used for the separation of charged compounds

( inorg. Ions, org. ions, AA, Proteins and Nucleic Acids)

Page 49: Chromatography new