Chromatography Forum

any one use polar organic solvent for SPME? such as meoh, acn?
although they facility the release of solutes from matrix, the downside is that they reduce the vapor pressure and saturated the SPME.
Am I right?

SPME is all about partitioning. And that includes the equilibrium between every component in the vial with the SPME fiber. And if you have a high level of solvent, the partitioning is between the vapor and a SPME fiber that is a lot more like the solvent than a fiber that does not have a lot of adsorbed solvent. So the nature of the fiber changes. This does not necesarily keep the SPEM fiber from being usable, but if you have a compund that is quite soluable in solvent in the vial (strong partitioning into solvent) - how much is going to partition into a SPME fiber, even if the compound is quite soluable in the fiber. Remeber teh partition coefficient is the ratio of concentratios - and there is not much phase on a SPEM fiber for the comound to "disolve" in (or be adsorbed onto).

You see water used with SPME for ethanol. The water is salted to make it even more polar - and to reduce the soluability of the ethanol in water.

If you have a sample in a volatile solvent, why not do a liquid injection ? The answer to that question will determine whay you need to use SPME, and whether it is likely to work.

Peter

You can use methanol as methanol won't bind to the fiber much but anything else will reduce your sample signal. I tried adding a few ul of a calibration mix in acetone to 2mL of water and got a 30% drop in many of the early compounds. DO not use chlorinated solvent they will destroy the fiber.