Zhang X K, Dutky R C, Fales H M
Chemical Structure Section, National Heart, Lung, and Blood Institute, Bethesda, Maryland 20892, USA.
Anal Chem. 1996 Sep 15;68(18):3288-9. doi: 10.1021/ac960245n.
Using MS/MS, we have identified ions at m/z 399, 421, 609.4, and 819.9 as those of tris (2-butoxyethyl) phosphate, originating in the gray rubber stoppers commonly used as closures in commercial sources of peptides and proteins. The compound is readily extracted by contact with organic solvents such as alcohol or acetic acid and even by water alone. Zinc salts of proteins are also observed, presumably from zinc oxide fillers present in the stoppers.
