Ch23-TCF

Ch23-TCF - Ch. 23 Intro. to Analytical Separations Solvent...

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1 Ch. 23 Intro. to Analytical Separations Solvent Extraction Toluene Water After one extraction, the fraction of solute, a , still in solvent 1 is q q = V 1 (derived on p. 502) V 1 + K V 2 After n extractions with the same V 2 each time, fraction of a remaining in solvent 1 is q n Fraction remaining = q n = V 1 n V 1 + K V 2
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2 Example 50 mL, with 0.10 M solute a in solvent 1, K = 5 (a) Extract once with 300 mL of a second solvent … q = 50 = 0.032 or ~ 3% left in solvent 1 50 + 5×300 (b) Extract 6 times with 50 mL portions of solvent 2 … q 6 = 50 6 = (0.166) 6 = 2.1×10 5 or 0.002% of a 50 + 5×50 left in solvent 1 Use a Distribution coefficient if more than one form of the solute exists – as in acid-base equlibria or metal-ligand complexation equlibria – see Harris .
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Chromatographic Separations - stationary and mobile phases Greater affinity for stationary phase 3 Note the definitions: Stationary phase, Mobile phase Eluent, Eluate
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Types of Chromatography - based on mechanism of interaction of solute with stationary phase 4 Typically metal oxides Alumina, Al 2 O 3 Silica, SiO 2
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7 Measurement of retention times in chromatography Adjusted retention time : t ' r = t r t m t m is the minimum time for a non-interacting
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This note was uploaded on 03/28/2011 for the course CHEM 300L at USC.

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Ch23-TCF - Ch. 23 Intro. to Analytical Separations Solvent...

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