Nitrates and nitrites

Agriculture is the largest use. Calcium nitrate and potassium nitrate are favourites for fertigation and greenhouse crops, and ammonium nitrate is used both as a fertilizer and as the main ingredient in industrial explosives. Nitrates also serve in glass and ceramics, heat transfer salt mixtures for concentrated solar power, waste water treatment and analytical chemistry. Sodium nitrite is used for meat curing, corrosion inhibition, dye manufacture and rubber chemicals.

Ask for the nitrogen content, water insolubles, pH, moisture, anti-caking treatment and granule size for fertilizer grades, or assay and heavy metal limits for technical and food grades. Nitrates are oxidisers and ammonium nitrate is tightly controlled in many countries because of its explosive potential, so expect licences and end-use checks. Nitrites are toxic. Fertilizer nitrates are classified in HS chapter 31, while technical nitrates and nitrites fall under HS heading 2834.