Sodium hydrogen selenite ( NaHSeO₃), also known as sodium hydrogen selenate, is an inorganic compound composed of selenium, sodium, hydrogen, and oxygen. It is a white or yellowish crystal that is soluble in water and acidic. Sodium selenite has certain applications in industry, mainly as a reducing agent, antioxidant and chemical analysis reagent.

1. Chemical analysis: In analytical chemistry, sodium selenite is used as a reducing agent to determine the content of certain metal ions, such as iron, copper, lead, etc.

2. Food additives: Sodium selenite is used as an antioxidant in the food industry, which can extend the shelf life of food and improve the quality of food. At the same time, it can also be used as a fortifier for selenium in food to meet the nutritional needs of the human body for selenium.

3. Agriculture: In agriculture, sodium hydrogen selenite can be used as a plant growth regulator to promote plant growth and increase yield. In addition, it can also be used as a supplement to selenium in animal feed to improve the health of animals.

4. Pharmaceutical field: sodium hydrogen selenite has potential applications in the pharmaceutical field, such as as antiviral agent, anticancer agent, etc. In addition, it can also be used in the preparation of organic selenium compounds for drug synthesis.

5. Ceramics and glass industry: In the ceramics and glass industry, sodium selenite can be used as an oxidizing agent to help control the atmosphere in the furnace and improve the quality of the product.

6. Photosensitive materials: Sodium selenite is used as a reducing agent in photosensitive materials, which can improve the photosensitivity of photosensitive materials.

7. Electronics: In the electronics , sodium selenite can be used as a dopant for certain semiconductor materials to improve their electronic properties.