Low solubility samples can cause some difficulties in flash separation. It is necessary to dissolve them in a solvent matrix that may not be compatible with the separation solvents.

In this case, the sample is dissolved in a strong solvent, mixed with silica and then evaporated to dryness.

Placing the silica/sample mixture in a Solid Sample Introduction Module (SSIM) allows the sample to be eluted on to the top of the separation column. Using this technique can improve the separation dramatically, as shown in the diagrams below:

 

Liquid Injection — no separation   Complete Resolution with SSIM

 

SSIM modules are available for all flash system sizes and can also be used as a pre-column. Simply place some clean silica inside the SSIM and inject the liquid sample as usual. The silica prevents impurities reaching the main column and therefore will extend its life.