By greg kovac on Wednesday, February 26, 2003 - 12:03 pm:
Estimated collegues:
in general,what is the idea in conditioning step of sorbent:
what solvent of general manner can I use;what factors Must I to have in my head ?
Thanks .
Greg
By Tom M. on Thursday, February 27, 2003 - 11:59 am:
Hi Greg,
Maybe someone involved in manufacturing will post. But, SPE columns are shipped dry. What type of SPE are you using. The C-18 SPE tubes contained some type of stabilizer - maybe something to prevent the tubes from adsorbing crud from the atmosphere. Anyway this material usually needs to washed off in the conditioning step. Usually 100% MeOH then water then load. You should just follow the manuf. recommendation for the conditioning.
By Uwe Neue on Thursday, February 27, 2003 - 03:12 pm:
There are many reasons to use a conditioning step. They depend on the sorbent and on the sample that you want to load.
A C18 is commonly not wetted by an aqueous solution. You try to load an aqueous solution, and you get no retention.
Even for sorbents - like Oasis HLB - that do not have this wetting problem, a conditioning is still recommended when you are dealing with a plasma sample. If you do not do this, the protein concentration in the plasma sample increases by about a factor of 2 during loading, since proteins are excluded from the matrix. This increases the viscosity of the sample, and you will now wait for day until you have flushed your sample through the SPE device.
In general SPE materials are very clean. AT least some manufacturers go through special care to prepare clean SPE cartridges.