If you want to spend the time and money,,,,,
you can send it to a refiner who specializes in platinum group
metals and let them know that you are trying to find the exact
amount of rhodium in that bottle and they can process it and weigh
it,,,,,, they probably will charge a hundred bucks or more,,,,,
or you can talk to a chemist who can figure out how to drop the
rhodium out of solution and filter and rinse it then weigh it on a
verry acurate scale......