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Lecture 7

Lecture 7 . Chromatography Intro!. Solid Phase Extraction. Load (sample). Eluent (solvent). Compounds of interest stick to sorbent. Compounds of interest released from sorbent. Waste. Extract. Chromatography. Mobile phase. Mobile phase. Load Sample (injection).

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Lecture 7

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  1. Lecture 7 Chromatography Intro!

  2. Solid Phase Extraction Load (sample) Eluent (solvent) Compounds of interest stick to sorbent Compounds of interest released from sorbent Waste Extract

  3. Chromatography Mobile phase Mobile phase Load Sample (injection) Compounds of interest in a plug Differential interaction with stationary phase separates compounds in time and space. Detector Detector

  4. Chromatography Definition Separation of components in a mixture based on the differential movement through a porous media under the influence of a mobile phase

  5. First Chromatography Column toluene sample

  6. What happens in a chromatographic column? Gas Chromatography (GC) Liquid Chromatography (LC) Distillation Liquid-liquid extraction

  7. Theoretical Plate GC - gas chromatography open tubular columns Silica support Stationary phase Gas (mobile phase)

  8. Theoretical Plate LC - liquid chromatography packed columns Silica beads Stationary phase liquid (mobile phase)

  9. Number of Theoretical Plates Length of the column L N = H Height equivalent of a theoretical plate

  10. Retention Factor Describes the strength of the interaction of a compound with the stationary phase tR-tM VR-VM k’ = = tM VM 1 < k’ < 10

  11. Solid Phase Extraction Load (sample) Eluent (solvent) k’ < 0.001 k’ > 1000 Compounds of interest stick to sorbent Compounds of interest released from sorbent Waste Extract

  12. Chromatography Mobile phase Mobile phase Load Sample (injection) 1 < k’ < 10 Compounds of interest in a plug Differential interaction with stationary phase separates compounds in time and space. Detector Detector

  13. Retention Factor (k’) Describes the strength of the interaction of a compound with the stationary phase

  14. Retention Factor (k’) Effect of k’ on Selectivity and Resolution in LC Dong, M. Today’s Chemist at Work. 2000, 9(2), 46-48.

  15. Selectivity Describes differential mobility of 2 compounds k’2 K2 =  = k’1 K1

  16. Resolution Describes how well 2 compounds are separated 2(tR2-tR1) Rs = tw1+tw2

  17. ( ) k’ 1 1+k’ 4 efficiency selectivity retention Resolution Describes how well 2 compounds are separated Rs = N1/2 (-1)

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