Metal impurities testing via ICP (Inductively Coupled Plasma) analysis is peformed for the following, along with acceptance specifications:

Al: Not more than 5.0 ppm
Fe: Not more than 20.0 ppm
Ti: Not more than 0.5 ppm
Mg: Not more than 5.0 ppm
Ca: Not more than 15.0 ppm
Na: Not more than 20.0 ppm

It is important to note that the actual levels may be significantly lower then those in the table.