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Modified Ehrlich's Reagent Formulation

T

techmeme

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Mar 6, 2013
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Hello Bluelight,

First post here. Specifically registered to ask this question. I have asked in a chem forum, but did not get much of a response. I am also not sure if I should have posted this in Advanced Drug Discussion, as this forum seems to talk more about test results than formulations.

What is the original Ehrlich Reagent, that had stability issues? There seems to be about 5 or 6 versions of the Ehrlich/Indole reagent floating around the inter-webs, but none describe whether they are the original or modified versions.

Thanks for any help/citations that can be provided.
 
I believe I have found it in the Handbook of Food Analytical Chemistry, Water, Proteins, Enzymes, Lipids, and Carbohydrates (p 657). It seems overly complicated, I understand why there are so many modified versions of it.

What is the current forensic standard for the (Modified) Ehrlich Reagent, is it still a 2 solution process?
 
this is a great reference for all reagent test contents: hxxps://www.ncjrs.gov/pdffiles1/nij/183258.pdf

ehrlich is aka DMAB reagent. very simple to make, 2gs of DMAB:50mL HCl: 50mL ethanol (everclear works)

first mix the DMAB with the alcohol, stir/shake into a solution... then CAREFULLY add the HCl, just start with a few drips. you will get some smoking untill you get about 5mL of the HCl in. after it stops reacting you can pour the rest of the acid in. it is normal for the reagent to get warm.

that is the original formula, idk about any modified ones.
 
Perhaps it refers to the "Renz and Leow" reagent which uses p-dimethylaminocinnamaldehyde instead. Maybe this is more stable. All sources say that Ehrlich's reagent should be made fresh.

No doubt you have read the wikipedia page, whose references I have meticulously hunted.

https://en.wikipedia.org/wiki/Ehrlich's_reagent
 
^I think he means the one that uses DMACA instead of DMAB. So it's called the Renz and Loew reagent, huh? I hadn't heard that name before, good to know!

Apparently R&L reagent has proven to be both more rapid and long lasting, yielding results that are easier to interpret1. At first glance, I thought this was referring to its stability, but now I'm thinking it might be how long the reaction colour sticks around? That seemed to be a major focus of this paper.

On the other hand, it appears that this reagent is not as sensitive to LSD as it is to other indoles, putting a major damper on its applicability. Additionally, it can be harder to read because the solution is already pink in colour.

The improved hallucinogen reagent seems to be much more stable, easier to use, and provides bright reaction colours. It appears to be the obvious choice for indole confirmation.
 
The other formulation with p-DMAB involves sulphuric acid and ferric chloride. It is better to distinguish some indole compounds than normal ehrlich with hcl and an alcohol.
Click to expand...

TLConscious said this.

DMAB is still not super stable though.
 
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