Testing method

A testing method for identifying the chemical state of metallic species in an ultra-trace concentration, comprising the steps of:

• providing a liquid chromatograph and an inductively coupled plasma mass spectrometer in series, wherein the liquid chromatograph comprises a liquid chromatography column;
• preparing a solution of a test substance containing a solution containing the metallic species and, continuously perfusing the solution into the liquid chromatography column, the concentration of the test substance in the solution being a concentration in the range of PPM to PPb, the metallic species are one of:
• metallic ions, metallic complex ions, metallic chelate molecules or metallic particles;
• and
• measuring an eluted fraction of the solution by the ICP-MS to obtain a penetration curve plotting penetration ratio versus time, the penetration ratio value of the penetration curve for the test substance gradually increases with time and tends to be stable;
• after obtaining the penetration curve of the test substance, a standard solution is perfused into the same liquid chromatography column or another liquid chromatography column, and obtaining a penetration curve of the standard substance for the penetration ratio and time, a presence of metallic species is determined by comparing differences in retention time and penetration ratio profile between the penetration curves of the test substance and the standard substance.