Ok time to put in my 2 cents. First to detect Hg make an fluoresce screen. coat a plane surface with a florescencent materiell then illuminate it with an ultraviolet source. Place the suspected Hg containing materiel between the emitter and the screen, The hg fumes will block the ultra violet source and you will see the fumes in the form of shadows, like smoke.. Very simple. Of course if you had access to a AA machine it it much simpler and quantitative measurable.
Remember it is the 'organic' Hg that is most dangerous.
Side issue, I think that it is vastly overrated. As an example, during wwII,i I was a master horizontal bombardier and Nordan Bombsight mech. On Guadalcanal, we worked in a closed Quonset hut with no windows or any kind of air conditioning, it was still considered top secret. We were supposed to commit suicide rather than to be captured -- yeah,I was about to commit suicide for something that was compromised in 1935
Anway we worked with open pools of mercury as a self leveling mirror to establish true vert on the sight.
Naturally we also killed flies and skeeters with liquid mercury squirted out of hypodermic needles and worked with open
containers of Carbon tetrachloride, now considered a positive cancer causing agent among other things.
In other words a environmentalist would have 'hysterics' today, yet none of us, that I could ever find, had any troubles. Perhaps it shows up later in life, but so far it hasn't with me and I am only 91 ---- hesh oro, or no coffee.
Our lil mercury mine in the sierras. This is our retort.

