The principle is to use battery power to cause an oxidation reaction on the surface of the material. Through appropriate control technology, the measured elements and reagents can form colored complexes. By detecting the depth of the liquid turning red, the main metal elements in stainless steel can be detected. The rapid measurement and specific formula are generally not disclosed to the outside world because this thing has applied for a patent.
Instructions for use: Place one drop of the test N8 on the surface of stainless steel, use a battery, put the positive electrode on the steel, and put the negative electrode on the measuring liquid bead, energize it, after oxidation, it will turn into a pink complex that will not retreat. It means that the nickel content in the stainless steel is ≥8%, that is, it has reached the 301 series standards.
You can refer to US EPA3060A:1996 UV-Vis analysis method.