[d0ct0r]

Hello guys,

I am trying to do analysis by raman instrument with 785nm laser wavelength, as I found a few articles that successfully done even profiling composition of pills. I am not able to acquire a sufficient quality spectra due to high fluorescence, this article:

https://chemistry.mdma.ch/hiveboard/serious/000423857.html

they claims that have "fluorescence background even in untreated seized samples is sufficiently low that there is little difficulty in obtaining good quality data with moderate 2 min data accumulation times" which is not my case, even pure crystalline MDMA gives me a very weak signal with very few small peaks, any ideas how it is possible that I am not able to acquire enough quality spectra? I will be much appreciate any respond, thank you very much.

[Corribus]

Fluorecence is always a problem for Raman. Usually the easiest solution is to change the laser wavelength, if you can. Do you have a 532 laser wavelength you can try? Although MDMA is fluorescent I would think with a 784 wavelength the contamination shouldn't be significant. Probably 532 excitation will be worse.

It may be helpful to better understand what you me by "analysis".  If the sample has other stuff in it, PL contamination may be coming from contaminants, not the primary analyte.

The Raman effect is also very weak. Proper sample preparation is important. A typical method is to crush finely and sprinkle over a low background substrate like aluminum foil.

By the way, a forum policy here is to not discuss certain aspects of illicit drug development, synthesis, and purification. Depending on where you take this thread, don't be surprised if it is shut down.

[d0ct0r]

Thank you for your answer, I really appreciate it. I hope that forum policy keep this because I am not discussing development, synthesis or purification, just doing this for harm reduction purposes and I saw many topics about MDMA here, my goal is to check how much MDMA content is in pill and possibly detect other substances and prevent people get overdosed or take something different than MDMA.

I know that easiest solution is to change wavelength, but I don't have this option right know and I am curious how they did obtain spectra using 785nm wavelength with usable fluorescence - like in the article. Both samples MDMA and pill should be without any contaminants.

I tried crushed MDMA but spectra and fluorescence was very similar, crushing did no effect. I can try crush the pill and use the aluminum foil and share result here.

[Corribus]

Do you have a reference sample of pure MDMA you can use? If you have no idea what else is in the pill (contaminant, excipient, etc), there's no way to know where the fluorescence is coming from. Using a standard reference material is SOP for developing and validating an analytical method.

[d0ct0r]

I tried measuring with aluminum foil and has no effect on it sadly. I have very pure sample of MDMA in crystalline form, but it is not a reference sample, there is little bit of yellowish coloring, maybe the leftover from safrole causing fluorescence?

I also found this article https://solutions.bwtek.com/acton/attachment/8353/f-037a/1/-/-/-/-/2018-TacticID-1064%20for%20MDMA%20Test.pdf

Looks like for pills it will be best 1064nm wavelength due to coloring