Selecting the appropriate packing weight and SPE cartridge size

The amount of sorbent and the size of the SPE cartridge is generally dependent on your sample: A simple approximation of how much sample can be loaded on an SPE cartridge is 5-10 % of the sorbent weight.

3 ml tubes are a popular size of cartridge and a good starting point for many applications. Smaller tube dimensions (1 ml) contain smaller amounts of sorbent and require less solvent for elution. This can make a more efficient separation which is useful if evaporation is required. Larger tubes can be used when larger volumes of solvent are required, for example where there is more than one extraction step.

A larger sorbent amount will help, if compounds are difficult to retain on a column.

Typical loading sizes