Headsapce:milk, acetone and butanol

[anisame]

Hi

when I "inject" milk, I do not get any peak which is fine for me since I want to use it as solvent(instead of water). Then when I inject milk with butanol(IS) I do get a small peak identified as acetone.
I do not understand the presence of this acetone peak since it is not there in the chromatogram of milk itself.
I thought that the decomposition of butanol could form acetone but I did not find anything about it in the literature.
An idea???
Thank you

[chromatographer1]

You may be seeing isopropanol in the isobutanol.

Perhaps you should check your butanol for acetone or IPA contamination or perhaps during sample preparation your atmosphere contained acetone or IPA fumes.

Worst case, try using another IStd and see if the same results occur.

Good luck

[Ron]

Many solvents will absorb organic vapors from the laboratory atmosphere. Dimethylsulfoxide is the classic example, it is a very good solvent, but very hard to get a clean blank. If you are doning extractions in the same lab where you are spiking the internal standards into the milk you will probably have extraction solvent contamination of your internal standard, especially if the internal standard has been stored in the same room. When I prepared samples in a hood for purge and trap analysis in the same room HPLC systems were used in, I could tell exactly which solvents were being used for HPLC simply by identifing the peaks in the blank.