SPE Hardware

The widespread use of SPE has resulted in several formats in which this extraction technique can be performed. 

Cartridges are the most used format in SPE. They are relatively low in price, mostly disposable, and with few solvent limitations. SPE cartridges can be obtained for normal phase, reversed phase, ion exchange, and mixed mode. 

The cartridges are filled with the sorbent, the amount varying from a few milligrams to several grams. The volume of the cartridge can vary from 500 gl to over 50 ml, depending on the capacity needed and the volume of the sample. 

Application in all steps is done on the top of the sorbent bed. Flow-through of the liquid is mainly generated by reduced pressure, which is created from the bottom. Most commercial cartridge-based SPEs are performed on vacuum manifolds that can handle several cartridges at a time. Other ways to generate a flow-through are pressure (from top) or centrifugation. Fully automated SPE systems are commercially available. 

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SPE hardware bleed. Wash the sorbent with the final eluting solvent during sorbent conditioning to remove interferences. 

Change the solvent being used in order to eliminate bleed from the SPE hardware, to eliminate impure solvents, or to stop the bleed from the instrument used for analysis. 

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