That's exactly why I DIY my own flavours 1) it's a LOT cheaper 2) I know what's going in it (buy from reputable companies for base ingredients who publish reports)
TFA/TPA are up front about "some" of thier flavours containing minimal amounts of Diacetyl but they have the DX line for those trying to avoid any sort of harmful substance ....when I say minimal it really is almost negligible
FA don't contain any nasties in thier reports
That's why i generally stick with these guys for flavour concentrates
VG/PG/Nic bases buy pharma grade only (avoid peppery sub standard nic)
That's it lovely no other ingredients in there
Get all my stuff from 2 places in the UK
Flavour Art UK ... flavours, VG, PG
Vapable.com for TFA/TPA flavours ...just bought Nic from them too looks good and very clean ..yet to use it (used to source from another place but was t happy with it) so I'll report back if it's crap
Both have quick delivery and had no issues with any order so far