There are lab's in maine, germany, pennsylvania, etc.
I went to my local vitamin shop, she cut my hair, and kept a supply of envelopes. i paid 50.00. later i wanted more things tested, she called the rep, got a supply of envelopes from germany, and we did a wide range of testing.
at a minimum
magnesium
potassium
calcium
zinc
copper
nickel
iron
aluminum
lead
etc.