# How to create the equivalent of luminol for a compound?

How would you go about creating a compound, like luminol, that would visibly react with monomorine I (5-methyl-3-butyloctahydroindolizine) on a household surface (like a kitchen floor)?

It is ok if the compund reacts with other similar compounds as well, as long as they aren't common to a household.

Background:

• Luminol is the chemical used by forensic investigators (like those on CSI) to detect trace amounts of blood at crime scenes. The luminol is sprayed over an area and when it comes into contact with blood (specifically, the iron), it exhibits a blue glow.
• Monomorine I is an ant trail pheromone (a trail guiding other ants to food).

Objective:

I'd like to be able to apply a compound on a surface and see the trails left by ants.

## 1 Answer

Probably not easily, especially if the concentrations are really low. Luminol + $\ce{H2O2}$ only works with blood because it's a catalytic reaction, i.e. it doesn't take much iron to create a lot of chemiluminescence. I'm not an organic chemist, but I'm not aware of any sort of similar reaction specific for this class of compounds. I did see this reaction: http://onlinelibrary.wiley.com/doi/10.1002/(SICI)1521-4168(19980501)21:5%3C315::AID-JHRC315%3E3.0.CO;2-V/abstract Unfortunately, it's not open access and I can't share my institutional access, but it's basically a photo-generated ruthenium complex that reacts with tertiary amines and indoles which might be applicable here, though I'm guessing is not sufficiently sensitive. It's not terribly selective so you might run into interference problems and in that paper they use it for HPLC detection so it may not be bright enough to see with the naked eye. (I have seen similar chemiluminescent compounds before and they're pretty dim, even with the lights out)

There are ways to produce visible changes in response to small concentrations of an analyte: LSPR, ELISA, etc. but they're a lot of work to implement for new analytes and probably too expensive for looking at a large area. Chemical imaging based on mid-IR or Raman spectroscopy may be applicable, though as far as I know, they're not geared for measuring large areas.

It seems that directly visualizing pheromone traces is a non-trivial task. Groups seem to do things like use image analysis (http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1002592) to estimate the levels of pheromones. I would like to have seen a comparison of their model with actual pheromone measurements and the way I would propose to do it is to take surface samples after the experiment. If a big sheet of paper was used as the surface, you could cut it up in a grid and extract the pheromone for analysis by LC-MS or whatever (or maybe even used directly as a paperspray emitter for MS). An ambient-ionization mass spec technique like LTP or DART would also probably be a good way to construct a surface map of pheromone concentrations.

Briefly: There are certainly ways of measuring trace amounts of things like pheromones, but a simple CSI-esque naked eye visualization probably isn't easily achievable.