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Lecture 6 Sample Preparation. Solid Phase Extraction (Exhaustive Extraction) Analyte either adsorps or absorbs to a solid support Large concentrations.

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Presentation on theme: "Lecture 6 Sample Preparation. Solid Phase Extraction (Exhaustive Extraction) Analyte either adsorps or absorbs to a solid support Large concentrations."— Presentation transcript:

1 Lecture 6 Sample Preparation

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

3 Solid Phase Extraction - Air (Exhaustive Extraction) Sorbent Environment Vacuum pump Ambient air Lab N 2 in Sorbent Sample

4 Solid Phase Extraction - Air (Exhaustive Extraction) XAD High surface area (290-750 m 2 /g) PUF Polyurethane foam TENAX Moderate surface area (19-30 m 2 /g) Thermally stable, appropriate for thermal desorption Sorbents

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

6 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 Sorbents Solid Phase Extraction - Water (Exhaustive Extraction)

7 Si C18 tails Silica-based SPE cartridges Procedure: 1. Condition cartridge 2. Load sample 3. Wash co-extractables 4. Elute analytes of interest 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 Only equilibrium extraction method described here. Often used to observed volatile materials in a laboratory setting. N 2 in Sorbent Sample Solid Phase Micro Extraction (SPME)

11 N 2 in Sorbent Sample Solid Phase Micro Extraction (SPME)

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

13 SPME fiber Sample k k


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