This PDF has some great notes on all different approaches for measuring selenium in soil, water, air, tissue samples, blood, urine, and semen. It references amounts needed, sensitivity, and discusses a lot of different types of spectroscopy:
One of the techniques we've discussed on the lists is atomic emission spectroscopy, which is like burning a sample and watching for the emission spectrum as it's heated. This has the big drawback that you'd have to mist selenium through a flame, which is almost certainly not good for your health. I'm trying to think of some kind of sampling chamber where you could do this inside Pyrex or otherwise contain the toxic vapor.
I started thinking about e-cigarettes, which atomize a liquid into a vapor, and are really compact and relatively inexpensive. (above image via Wikipedia) I wonder if there could be some kind of very small flame and an e-cigarette could atomize/vaporize a sample liquid through it, all in a small, semi-disposable clear chamber.
Maybe I need to buy an e-cigarette?