I am writing a book and as part of the plot one of the characters has a plant that contains alkaloids in tincture form. They want to do a test to detect for the alkaloids so they use the Dragendorff's reagent test. Quote below:

Bindweed contains alkaloids. The Dragendorff's reagent is a simple test to detect for them. They had all I needed in the chemistry lab... bismuth nitrate, hydrochloric acid, potassium iodide. When I added milk to the solution it turned orange confirming the presence of alkaloids. I did a control test too and nothing happened.

Would this technically work?

  • $\begingroup$ Here is how you make Dragendorff's: this prep uses acetic acid rather than hydrochloric communities.acs.org/thread/4183 I've seen other preps that use tartaric acid. It is possible to get false positives from other plant extracts that have a basic centre researchgate.net/post/… $\endgroup$ – Waylander Jan 9 '19 at 13:55
  • $\begingroup$ Thank you for coming back! I need to add that in my book the bindweed plant has been made into a tincture, so dissolved in alcohol, and then a few drops of it are added to a glass of milk. It is this milk that is being tested. I don't know if the Dragendorff's test would still pick up the alkaloids of the bindweed in this form? $\endgroup$ – Cari Jan 10 '19 at 12:17
  • $\begingroup$ It should if the alkaloids have extracted into the alcohol which I think they would. You should have them run the blind of testing milk without the tincture to see if that tests positive - (also an author) $\endgroup$ – Waylander Jan 10 '19 at 12:57

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