Chromatography Forum

Hi Everybody,
I have to measure residual methanol (50-100 ppb level) in a polymer: PVP (polyvinylpyrrolidone). Unfortunately I don't have access to head space autosampler.
I think to start with solubilization of PVP in DMF (dimethyl-formamide) or dichloromethane and inject 1uL of solution (splitless mode). I have a WAX column (60m 0.25 I.D., 0.25u) or RTX35 (35% diphenyl 65%polysiloxane) and I want to start at 40°C and slowly heat up to 200°C. I think the best should be working in SIM mode monitoring the 32 (or 31) m/z but my fear is about the noise I get with this low ion.
Do you think is possible to analyze it by SPME?


Have you got some suggestions?


Thank you in advance for the help
Have a good day,
Davide

Hi, well this is a real issue, but for me its possible to do 2 things about that:
1) If you have head space vials you try to perform a manual Head Space with a fid detector,try to spike in a pice of Polymer an amount of methanol prior to resuspend the polymer in aqueos solution and adding a salting out treatment ( for cualitative porpouse), using a inowax or DB wax capilally column.Then if you see the paçeak try to standarize the methods in oven at 80 dregress for 30 minutes.I kown its not friendly but its a possibility.
2)Using the same as you said but in ion SIM with the polar capillary column and ( check well the air and water because you are near the noise area), and decreasing the ION ENERGY to 35 or 30 eV having the cuasi molecular ion.....( for me it will be dificult because of the limits range are used and you are under a noise area of ion 44 ( C02) 32( O2) and (18 water).

IF you want try to send me an e-mail I apreciate a lot your answer, and sure I will tell you some datails about runing a methos in GC-MS at low masses!!

My e-mail dcobice@gmx.net and my work e-mail is dcobice@bai.boheringer-ingelheim.com ( R&D mass lab)