By Jan on Friday, July 4, 2003 - 01:34 am:
Hello forum members,
Recently I was asked to identify a white precipitate in a seizured bottle. The bottle contained an organic solvent (nailpolish remover), but the interesting part was a white deposit on the bottom of this bottle. The bottle was suspected to have contained liquid ecstasy, or GHB (gamma hydroxy butyrate).
I took a mg of the deposit, dissolved it in water and did ion-trap LC-MS-MS. On C18 (5%MeOH), I got an (almost) unretained peak, with no particular UV spectrum, and in ESI+ an ion at 198. MS2 gave 180 and 163 ions. MS3 on ion 180 gave ions 163, 145 and 127. Clearly this is not GHB. But wat is it then?
I am looking for a polar molecule with no chromophore, a molecular weight of 197, and probably some hydroxyls and an amino group.
I was thinking of some kind of aminosugar, but the ones I know (glucosamine and galactosamine) don't have the right MW.
A guess anyone ?
Jan
By Anonymous on Monday, July 7, 2003 - 09:33 am:
I looked up the structure of GHB and had a quick thought. perhaps you'll have better luck getting this compound to fly in negative mode if your system will allow for it. Given it's acidic nature, it would seem to be anionic at a neutral pH. As for your original question of the origin of 198, I can't be of any help. Re-looking at the structure again, I'm not sure about the MW of 197/8. It seems too high for the compound I'm seeing (Hydroxybutyric acid ).
Best regards
Jim
By Jan on Tuesday, July 8, 2003 - 01:09 am:
Actually the first run I did (and always do) when looking for unknowns is a pos/neg switch. I did not see any ions for GHB in negative mode, the only negative ion I saw was 196, but not intense enough for my ion-trap to do MS2 (only 2E4). Positive mode gave lots of 198 ions...
Thanks for the input
Jan
By Cindy on Tuesday, July 8, 2003 - 11:03 am:
Try to take a small amount of the deposit and run it on a FT-IR. If it is an organic matter it should have a spectrum and you can look it up in an IR library.
Cindy
By Jan on Tuesday, July 8, 2003 - 11:32 pm:
Cindy,
This is something we tried as well. The spectrum was not very nice though. Matches were never higher than 0.700 (where 0.999 is a perfect hit). Highest scores were for dextranes, large polysaccharides. Possible structural units alkyl groups, hydroxy compounds and aliphatic secondary alcohol. If it really is a saccharide, what else can I trie to determine its structure ?
Jan
By Anonymous on Wednesday, July 9, 2003 - 03:56 am:
If it were a saccaride, you might try a neutral loss scan on triple quadruple.