Method for detecting impurities in ammonium hydroxide

A method for detecting impurities in ammonium hydroxide, the method comprising:

• preparing ammonium hydroxide having a concentration in a range of 1 wt % to 5 wt %;
• preparing a liquid chromatography separation system comprising a stationary phase and water;
• injecting the ammonium hydroxide prepared having a concentration in a range of 1 wt % to 5 wt % into the liquid chromatography separation system;
• and
• detecting whether impurities are present in the ammonium hydroxide injected into the liquid chromatography separation system,
• wherein the stationary phase comprises:
• silica;
• and
• a functional group that is combined with a surface of the silica and is represented by the following chemical formula,
• wherein, R is n-octadecyl, and a symbol of * means that the functional group is combined with the surface of the silica.