There are major elements and trace elements. For the major elements that are measured in PPT (Parts Per Thousands) you can find hobby level test kits.
But "true" trace elements are measured in the PPM or PPB (Parts Per Millions or Parts Per Billions) and these are not so easy to measure.
To read these kinds of values, you are going to find, people are using ICP testing by one of the several companies out there offerring testing services to the aquarium hobby.
Dave B