The content of HDO in the water on the earth is about 1/3200, that is, one out of every 3200 water molecules is HDO. HDO and H2O can be separated by distillation, electrolysis or chemical methods, and the chemical separation method has the highest efficiency ratio. The Girdler sulfide process is commonly used in industry, using hydrogen sulfide to “extract” deuterated water in water at 30°C, and then exchange it with water at 130°C to obtain deuterated water, and obtain deuterated water with higher purity through multi-stage exchange. In addition to hydrogen sulfide, ammonia, methylamine, etc. can also be used to separate and purify deuterium water (also known as heavy water); with deuterium water, the preparation of deuterated reagents is easy: