[Dolphinsiu]

Solid phase extraction (SPE) is becoming more popular in the extraction and ‘clean-up’ of samples before instrumental analysis.  Outline the advantages and disadvantages of using SPE in the sample pre-treatment step as compared to the more conventional solvent extraction method.

That's what I am not sure the following is true/false

However, SPE still have some disadvantages.

1. SPE columns are more expensive than conventional solvent extraction columns. i.e. the use of expensive instrumentation to load the separation column with the slurry. T/F (I am sure that it is true!)

2. Application of SPE to particle-laden water samples can be a vexing problem because repeated extraction is required for extraction of strongly adsorbed substances, added to the fact that suspended particles may plug the SPE membrane and decreases the flow rate so much that it effectively stops, but it is not a serious problem in simple solvent extraction. T/F

3. The set-up in SPE is more complicated. T/F

Thank you!

[Andy TB]

Solid Phase Extraction (SPE) is a much better way to clean up and concentrate samples, especially those that are water based. They are usually supplied in the form of HPLC packing in either plastic syringes or cartridges. In the UK they are about £1 (2$) each. Look up SPE in a suppliers catalogue such as http://www.sigmaaldrich.com/Brands/Supelco_Home.html.
The main advantage is that you don't need to use gallons of organic solvent or distillation apparatus to concentrate the extract - much safer and cheaper.
If the sample is full of insoluble crud, then yes, it could block the SPE cartridge. We usually put our samples into a centrifuge first to spin it out.
An even better sample preparation method is Solid Phase Microextration (SPME), especially for GC work.
Try http://www.sigmaaldrich.com/Brands/Supelco_Home/Spotlights/SPME_central.html