DIY mass spectrometer measures potassium in dietary salt substitute

How to build and operate a simple mass spectrometer. Please ask questions in the comments, as always. (I had to reupload this video to fix the ending I m very sorry if your early comments were lost ) Scientific American article: is a good value for the entire back issue in plain PDF format, and an example of a publisher being reasonable. I m happy to support this. Original Dewdney paper: