[NMR spectroscopy][1] is a technology that is used to identify molecules. So-called "NMR spectra catalogs" document the [spectra][2] of various known compounds. Acquiring these spectra requires purified samples, expensive equipment, and time. In addition to making next-generations of this technology into something that would be practical for realtime "smelling", you'd have to match up catalog entries with what dogs actually respond to. That's going to take a fair bit of work.

There's some literature online about growing [olfactory sensory neurons][3] in a Petri dish ([with difficulty][4]). If we can learn how the [signaling pathways][5] work for "odorant detection" for specific odorants or "fragrances" that we already know dogs perceive, perhaps we could genetically engineer a cultured neuron cell to "light up" a [fluorescent marker][6] or issue some other signal that is perceptible to humans, whenever some dog-specific odor wafts in. I suspect this would be more realistic than "tabletop NMR" in our lifetime.


  [1]: https://en.wikipedia.org/wiki/Nuclear_magnetic_resonance_spectroscopy
  [2]: https://en.wikipedia.org/wiki/Spectroscopy
  [3]: https://en.wikipedia.org/wiki/Olfactory_receptor_neuron
  [4]: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3466484/
  [5]: https://en.wikipedia.org/wiki/Cell_signaling#Signaling_pathways
  [6]: https://en.wikipedia.org/wiki/Fluorescent_tag