
Thanks Boognish. Glad someone finds it useful
So here is my research on distinguishing Fentanyl and it's analogues with color reagents.
TL;DR: - impossible (to be certain)
I have tested GC/MS verified samples of Fentanyl, Furanylfentanyl, Butyrfentanyl, 4-FBF (4fluoro-fentanyl/para-fluoro-butyr-fentanyl) and Acetylfentanyl
Fentanyl
Marquis:
yellow to red
Mandelin: slow green
Mecke: no reaction
Ehrlich: no reaction
Ehrlich-TS: no reaction
Froehde: no reaction
Simons: no reaction
Liebermann: reddish
4-FBF
Marquis:
orange to red
Mandelin: slow green
Mecke: no reaction
Ehrlich: no reaction
Ehrlich-TS: no reaction
Froehde: no reaction
Simons: no reaction
Liebermann:
orange to red
Butyrfentanyl
Marquis:
orange to red
Mandelin: slow green
Mecke: no reaction
Ehrlich: no reaction
Ehrlich-TS: no reaction
Froehde: no reaction
Simons: no reaction
Liebermann:
orange to red
Furanylfentanyl
Marquis:
brown
Mandelin:
brown
Mecke:no reaction
Ehrlich: no reaction
Ehrlich-TS: no reaction
Froehde: no reaction
Simons: no reaction
Liebermann:
red
Acetylfentanyl
Marquis:
orange
Mandelin: slow green
Mecke:
yellowy
Ehrlich: no reaction
Ehrlich-TS: no reaction
Froehde: no reaction
Simons: no reaction
Liebermann:
red
I have bolded what stands out, however these are such small details which can be affected by number of factors (amount, age of reagent, temperature, lightning, sample impurities, sample texture) that in my opinion it's impossible to be certain. Luckily, with the exception of fentanyl, they have a somewhat similar dosage (actual dosages vary moderatly) so mistaking analogues listed here might not be that extremely fatal.
Having yellow, orange or red doesnt help with marquis, since a smaller amount could produce orange, whilst a bigger chunk will turn it red or even brown.
Plese be aware that there are A LOT of fentanyl analogues, which are still unresearched in terms of regent results, and lot's of them have an even smaller dosage than fentanyl itself and probably same reagent results.
They also behave very similar on the TLC (eluent: methanol/ammonia). If someone with a bit more chem knowledge can recommend an eluent that would be more effective in distinguishing them, please let me know
If possible, always get your stuff lab tested. Depending where you live you may even have free lab checking.
If not possible the only "safe" solution i can think off would be starting with 1 microgram and then going up. (google carfentanil and W-18 ) :D