Hi Professor Forsum,
Unfortunately, our GC-MS library was not set up to detect trimethylamine, so while it could well have been there, and based on your data and that of others almost certainly was, our analyses were not sufficient to detect it. It is interesting though that each of trimethylamine, cadaverine and putrescine are biogenic amines formed through the decarboxylation of amino acids, suggesting a common path leading to the odor attributed to BV. There are actually a couple of other articles by Zeev Karpas and colleagues at the Nuclear Research Center in Negev, Isreal that have previously shown each of trimethylamine, cadaverine, and putrescine associated with BV.
Chaim et al. (2003) Eur. J. Obstet. Gynecol. Reprod. Biol. 111:83-87
Sobel et al. (2012) Eur. J. Obstet. Gynecol. Reprod. Biol. 163: 81-84
and
Karpas et al. (2002) Anal. Chim. Acta. 474: 115-123.