[LynnC]

helo there.im a newbie here. would like to ask some questions regarding some cleanup method for polyaromatic hydrocarbon compounds.can anybody please help?
thanks alot

[mike]

You have spilled them? More information please..

[LynnC]

Nope i didnt spilled them.
I am currently developing a method to determine polyaromatic hydrocarbon compound (PAH) in edible oil using GC-FID.
Got some prob with my cleanup method though i follow AOCS method exactly....i suspect its the alumina quality that i used currently, which is not strong to adsorb the triglycerides before injected into GC.
Any feedback?

Thanks!

[ssfrstlstnm]

You need to give more details if you want help. What type of alumina did you use (mesh, acid/basic, etc.)? Did you activate it? What solvents were used for the cleanup? Just give us the entire procedure.

[LynnC]

ok im sorry bt that, im kinda new here and desperate for help from experts. I use alumina activity 4 to be packed into a glass column, filled the  column with light petroleum ether ( boiling point 40-60 deg C), add my oil solution (without spiking) and elute it.
the solution is prepared using the same type of petroleum ether also.the first 20 mL of eluate is discarded and i only collect the next 80 mL for drying.
but i found that tryglycerides are not trapped bcos i can still see oil residue in my flask after the cleanup.

[mike]

So are you discarding the initial 20mL with or without checking what is in it?

Also, do you collect small amounts off the coloumn and check each fraction? or are you just collecting one fraction of 80mL? How do you know that you are not collecting the fraction you want then simply running the unwanted fractions right into the same flask?

I may be on the wrong track here..

[LynnC]

what i am trying to do is to check whether the adsorption of triglycerides is complete using the alumina. I found out the 80 mL eluate still contain triglycerides, meaning, the first 20mL also have.so, my adsorption is not complete. That is the problem is face.
If residues are not found in the eluate, means the alumina can be used for cleanup.
feedback pls.