Gel permeation chromatography (gpc) by kausar

To grow the concept of GPC

1. Gel Permeation Chromatography (GPC) Presented By Md. Kausar Ahmed Lecturer Department of Chemistry, BUET 1

2. Introduction to GPC/SEC Mode of liquid chromatography Determine the molecular weight of the polymer Separate the components of a mixture on the basis of size Determine the molecular weight distributions of polymers First GPC/SEC columns were packed with gels, hence gel permeation Gel permeation chromatography (GPC ) system 2

3. GPC Components Main components 1) Stationary Phase 2) Mobile Phase 3) Columns 4) Pump 5) Detectors 1- Chemically inert 2- Mechanically stable 3- Has ideal and homogeneous porous structure (wide pore size give low resolution ) 4- Uniform particle and pore size. 5- The pore size of the gel must be carefully controlled . Example- Dextran 1) Properties of Stationary Phase 3

4. Material Solvent Synthetic elastomers ( polybutadiene , polyisoprene ) Toluene PS, PVC, Styrene-Butadiene Rubber , Epoxy resins Tetrahydrofuran (THF) Polyolefins Trichlorobenzene Polyurethane Dimethylformamide (DMF) Proteins, polysaccharides Water / Buffers 2) Mobile Phase 4

5. Column Commercially Available Columns include Analytical column- 7.5–8mm diameters. Preparative columns-22–25mm Usual column lengths-25, 30, 50, and 60 cm. Narrow bore columns- 2–3mm diameter have been introduced 3 ) Column 5

6. 4) Pump Either syringe pumps or reciprocating H ighly constant flow rate 4) Detector Refractive Index (RI) Detector ( Universal Detector) Ultraviolet (UV) Absorption Detector Evaporative Light Scattering Detector (ELSD) 6

7. Experimental Setup 7

8. Calibrations Calibration graph Use polystyrene of different molecular weight as standard At least 5 polystyrenes One calibration uses for max 15 days 8

9. Sample Analysis Preparation of Samples (1mg in 1mL) Chosen of appropriate solvent Run the samples maintaining all the software parameter Data analysis GPC chromatogram of Pt-poly- ynes 9

10. Separation Mechanism 10

11. Types of polymer distribution Different polymer molecular weight distributions Monodisperse P olydisperse 11

12. M w > M n always !!!! A) Weight-average molecular weight corresponds to the size of the polymer chain A second order expression B) Number average molecular weight, corresponding to the chain length of polymer A first order expression Weight average molecular weight emphasizes heavy molecules Can you assume the population of a town? 12

13. Advantages and Disadvantages Advantages: Short analysis time Well defined separation Narrow bands and good sensitivity There is no sample loss Small amount of mobile phase required F low rate can be set Disadvantages: Limited number of peaks that can be resolved Filtrations must be performed before using the instrument Molecular masses be too close for the GPC separation to show anything more than broad peaks 13

14. Points to be Noted 1. Gel permeation chromatography/size exclusion chromatography is a type of high performance liquid chromatography (LC). 2. GPC/SEC can be performed in a wide range of solvents. From non-polar organics to aqueous applications. 3. GPC/SEC uses columns packed with very small, round, porous particles to separate molecules contained in the solvent that is passed through them. 4. GPC/SEC separates molecules on the basis of their size, hence ‘size exclusion’. 5. The first GPC/SEC columns were packed with materials referred to as gels, hence ‘gel permeation’. 6. GPC/SEC is used to determine the molecular weight distributions of polymers. 7. The particles in the columns are made from polymers that have been cross-linked to make them insoluble, or inorganic materials, such as spherical silicas . 14

15. THANK YOU ALL 15