Tungsten is the core element of ammonium metatungstate, and its content is typically reported in the form of tungsten trioxide (WO?). The WO? content in industrial-grade AMT is generally required to be between 89% and 92%. Common determination method of tungsten content includes:

Inductively Coupled Plasma Mass Spectrometry (ICP-MS): AMT is dissolved in water, diluted, and introduced into an ICP-MS instrument to detect the characteristic spectrum of tungsten ions. This method offers extremely high sensitivity, capable of detecting tungsten content down to parts per million (ppm) levels, making it widely used for high-purity AMT analysis.

Gravimetric Analysis: AMT is heated to 600–800°C, decomposing into WO?. The residual mass is then measured to calculate the WO? content. Although this traditional method is time-consuming, it provides reliable results and is well-suited for laboratory validation.