Chromatography Forum

I am currently doing a project, to detect bibenzyl, dibenzyl disulfide in insulating oil. We are trying to use 500mg alumina neutral to extract both from insulating oil. However, I only manage to extract dibenzyl disulfide. It seems that bibenzyl passes through the catridge w/o being absorbed. Anything wrong with the SPE selection?

laucch123,

How do you know it is not being adsorbed versus it is not coming off the cartridge? Can you tell us more?

Best regards.

It will only be absorbed if the elution solvent is weaker than the analyte. In normal phase chromatography (ie alumina), less polar solvents are weaker than more polar solvents. So bibenzyl will only sorb if your solvent is hexane (or heptane, etc). It can then be eluted using pretty much any other solvent. If you give some more details of your procedure, maybe we can be more help.

I had prepared these two components in an insulating oil. Then I take 500mg of this calibration standard diluted with 1cc hexane, then the diluted standard penetrated into the SPE catridge. The catridge is then washed with 1cc hexane for three times. Finally with 1cc of benzene. And analyze the benzene with GC MS. I also analyze the hexane eluted from the catridge and found that most of the bibenzyl is in there. I think this will work but now just no idea what is freaking wrong..

Perhaps their are aromatics in the oil that are saturating the SPE cartridge and causing the bibenzyl to elute in the hexane fraction. Maybe you can try using a smaller volume of oil or diluting the 500mg to a larger volume prior to loading it onto the cartridge?