Chromatography Forum

Is it acceptable to extract THM in nhexane and not it pentane. I am writing this because there is always some trace amout halocarbons being detected in pentane.

I extract THMs using MTBE and there are sometimes issues with contamination in the solvent, especially chloroform. I have mostly resolved this by having the solvent shipped directly from the manufacturer and requesting the newest batch they have. It seems the older the solvent is, the more likely it has picked up contamination in the meantime.

-Julie

Well its the same problem here. Though i pay a good amout to purchase the best quality form Merck after certain time i start getting these peaks in the solvent.

I thought changing the extraction solvent can be one of the option.

The appearance of halocarbons in these solvents can only be due to contamination by airborne vapours. Keep your solvents (even in closed bottles) away from anywhere that halocarbons are used. Order solvents in the smallest bottles that you can find, in the hope that you can use a whole bottle before the contaminants build up. Equip your solvent bottles with autodispensers so that you do not have to repeatedly open the top to get the contents out; look for dispensers that have vent tubes that a charcoal trap can be attached to.

Peter

Dear Peter,

Thanks of this advice. I woluld do like to clarify that some chloroform bottles kept in nearby labs might be strong possible source. The problem with working in Govt funded research lab is nothing is in your control. More over there are many labs within the institute.

I would check out a dispensor as you mentioned.