It's not as accurate as mass spec but generally speaking you can test for geavy metals using certain acid and color changing indicators (in known concentrations) over a range of sample dilutions. Even better if you have a reference sample of a known concentration of the target, like manganese. Sometimes the chemical is not itself an acid but nevertheless reacts with the target.

For example, high concentrations of manganese will react with peeiodate to make a red/broan color. You can buy a set of 100 pouches of periodate for manganese testing on Amazon for $50.