GB/T 23362.4-2009 standard specifies the determination method of aluminum, iron, copper, zinc, cadmium, lead and thallium in high purity indium hydroxide. This part uses Inductance Coupled Plasma Mass Spectrometry (ICP-MS), which is suitable for the determination range of mass fraction of these elements: aluminum, iron, zinc, lead is 0.00005%~ 0.0040%, copper, cadmium, thallium is 0.00002%~ 0.0040%. The sample is first dissolved with nitric acid, and then aluminum and iron are determined with scandium as the internal standard, and copper, zinc, cadmium, lead, and thallium with rhodium as the internal standard. The content of each element is calculated by collision/reaction cell and isotope signal strength measurement in normal working mode. This method requires the use of high-grade pure reagents and high-purity water, and the preparation of standard solutions to ensure the accuracy of the test.