1. Lecture 6
Sample Preparation

2. Solid Phase Extraction
(Exhaustive Extraction)
Analyte either adsorps or absorbs to a solid support
Advantages
Large concentrations possible
Limited use of solvents
Very effective clean-up technique
Disadvantages
Time consuming
Precision can be difficult
Expensive

3. Solid Phase Extraction - Air
(Exhaustive Extraction)
Vacuum pump
Ambient air
Environment
Sorbent
Lab
N2 in
Sorbent
Sample

4. Solid Phase Extraction - Air
(Exhaustive Extraction)
Sorbents
XAD
High surface area ( m2/g)
PUF
Polyurethane foam
TENAX
Moderate surface area (19-30 m2/g)
Thermally stable, appropriate for thermal desorption

5. Solid Phase Extraction - Water
(Exhaustive Extraction)
Sorbent
Environment
Pump
Water
Water sample
Sorbent
Lab
Vacuum manifold

6. Solid Phase Extraction - Water
(Exhaustive Extraction)
Sorbents
Silica-based stationary phase
Similar to LC phase - C18 most common
Limited pH stability
‘Finicky’ to handle
Polymeric
Stable from pH 1-14
Not ‘finicky’

7. Silica-based SPE cartridges
Procedure:
1. Condition cartridge
2. Load sample
3. Wash co-extractables
4. Elute analytes of interest Si
C18 tails
Tails ‘solvate’ during step 1 (conditioning), will collapse if the cartridge goes dry. Extraction is ruined

8. Polymeric SPE cartridges
Procedure:
1. Condition cartridge
2. Load sample
3. Wash co-extractables
4. Elute analytes of interest
No tails to ‘solvate’, and so extraction can continue even if cartridge goes dry

9. Polymeric SPE cartridges
Because of the wide pH stability are able to use pH to control extraction. Very selective and effective extraction technique.

10. Solid Phase Micro Extraction (SPME)
Only equilibrium extraction method described here.
Often used to observed volatile materials in a laboratory setting.
N2 in
Sorbent
Sample

11. Solid Phase Micro Extraction (SPME)
N2 in
Sorbent
Sample

12. Solid Phase Micro Extraction (SPME)
SPME holder
SPME fibre
Sample

13. Solid Phase Micro Extraction (SPME)
SPME fiber k k
Sample