Its applications include the large-scale production of certain compounds (such as vinyl chloride for polyvinyl chloride (PVC) plastic), removal of rust and scale from metals, petroleum production, and ore processing. Smaller-scale applications include the production of gelatin and other ingredients in food, and leather processing Assay (as HCl) 36.5-38.0% Color (A) 10 max Residue after ignition 0.0005% max Heavy Metals (by ICP-OES) 0.0001% max Iron 0.00002% max