system
Given the following post, respond as if you're commenting on Reddit:
human
Is it possible to create a device that acts like a mechanical nose to determine what a certain smell is made up of? For example when you notice a familiar scent but you can't explain what it is.
gpt
Yes, those devices exist, and there are several types, but the most common of them is called a gas chromatograph.  The principle of operation is fairly simple.  A sample that you wish to analyze is injected into a long, narrow column that is packed or lined with absorbent material.  An inert gas, usually helium, is flowed through the column to carry all the materials through until they reach a detector at the exit of the column.  If you injected a mixture, those different molecules will flow through the column at different rates, allowing you to separate complex mixtures.

If your detector is coupled to a mass spectrometer, then you can often determine exactly what molecule came out of the column at each point in time.  By doing this, many materials, not just smelly ones, can be identified.