# 03 - Extraction

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```					ExtractionS
Liquid

Extraction
Super-
Solid
critical
phase
fluid
Solute Distribution Equilibrium
• In LLE, most common: 2 immiscible L

Saq D Sorg                 
S 
org
KD
S 
aq

• Preferable condition:
– One solute KD<1, while another KD>1

     
% E  1  q n  100
n
     Vaq       
%E  1                   100
 K DVorg  Vaq 
               
So, how many time of extraction?
• One big batch of solvent, of several small
batches?
D=1

1 L of water     5g    1 L organic solvent  50% recovered
containing
10 g of solute    5g    1 L aqueous        50% left in raffinate
D= 1
Ratio of 1:2

1 L of water            3.3333 g     500 mL organic solvent  recovered
containing
10 g of solute           6.6666 g     1000 mL aqueous  raffinate

1 L of water
2.2222 g    500 mL organic solvent
containing
6.6666 g of
solute
4.4444 g    1000 mL aqueous

For most analysis,
recovery must at least
Total recovery: 2.2222 g + 3.3333 g = 5.5555 g         99.9% in order to be
Smaller batches are better!                   quantitatively reliable!
Now, calculate if extraction been done
using 4 portion of solvent
Consider solute of ML

• If no other equilibrium exist, CML = [ML], D =
KD
• But certain solute forms more than 1 sp. &
involves more than 1 equilibrium within one
or both phase
– Eg: involving ionizing complex
– Mn+ + Ln- D ML
• E.g.: involving ionizing complex
Mn+ + Ln- D ML
(metal) (ligand) (complex)

• So, equilibrium expression:

K ML 
ML               CML.aq  M aq  Laq
M aq Laq
K ML 
ML                                M aq    ML
M aq Laq                                    K ML Laq

If no equilibrium exist within organic phase,

MLorg
D
MLaq  M aq                                              The distribution of
complex not only
depends on KD but
MLorg             K D K ML Laq                     also conc. of ligand
D                         
 M aq  K ML Laq  1
MLaq              
 K ML Laq                                  Also applicable if other
                                             types of equilibrium exist
• e.g.: pH, masking agent
Solvent
• Essential part of extraction especially LLE is
the solvent itself!
• Criteria of solvent:
– Solubility distribution coefficient, KD
– Solubility of extractant in phase 1 solvent
• Refer Jadual 4.1
Solvent Extraction
Liquid
extraction

Liquid                In cleaning process:
Solid sample                                            continuous, so that
sample
all analyte can be
extracted out
Batch S-L          Cross-         Counter-
ext.           current LLE     current LLE

Continuous
Batch          Batch
S-L ext.

Continuous        Continuous
Solid sample extraction
• Easiest way, immerse in solvent
that can dissolve analyte w/out
using high T
– Usually not
thermolabile
– E.g.: Soxhlet
Liquid sample extraction
• Known as LLE
• Based on distribution of analyte between 2
immiscible solvents

Phase 1             Phase 2
- Contain analyte   - Extractant
- Usually aq        - Usually aq
Solutions?
Solid Phase Extraction
Solid Phase Microextraction
Stir Bar Sorptive Extraction
Vial
Sample
Magnetic   solution
stir bar
Stir bar
Coating material Glass              Magnetic
stirrer
70% recovery
SPME               SBSE

Figure 2.7: Theoretical recovery for solutes as function of KO/W for SBSE (10 mL
sample, 50 μL PDMS) and SPME (10 mL sample, 0.5 μL PDMS).
Supercritical Fluid Extraction

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