[MOTOBALL]

Dr. Hall,

If you use an isotopic mass & pattern calculator ( e.g. envipat.eawag.ch) for your signals at m/z 199 (C9H10O3S1 + H+; absent) and 317 (C13H20O5N2S1 + H+; present)
you will get the plots that I have attached.
The points to not e from this are,

(a) Rel. Int % of m/z 200 is ~1.1 x C9 = 9.9
(b) Rel Int  % of m/z 201 is ~4.4 x S1 = 4.4

So you can get a good estimate of Cn in a molecule, and the [MH+ +2]+ relative intensity divided by 4.4 gives you the Sn count.  The M+2 peak for 34S is a real standout!!

Well apparently, I cannot attach a spectrum, but if  you use that calculator you will see the isotopic patterns very nicely.

You need a plot like these from your MS lab for all of your mystery signals, m/z 168, 210, 218, 279, 317.

Regards,

Motoball