I found a couple of products and was wondering if it would be worth trying to isolate the phosphonic acid, use as is. I'm having trouble locating MSDS but the product ingredients are as follows......
PRODUCT #1
Sodium Chloride , Antimicrobial Buffer System ABS , Sodium Borate , Boric Acid , Sodium Perborate , Hydrogen Peroxide 0.006% , Phosphonic Acid
Product #2
Sterile Ophthalmic Solution Containing: Microfiltered Hydrogen Peroxide 3%; Sodium Chloride 0.85%. Stabilized With: Phosphonic Acid. Buffered With: Phosphates
Product #3
Hydroxypropyl methylcellulose, 0.3%; with carbopol 980, phosphonic acid, purified water, and sorbitol; sodium perborate (0.028%) added as a preservative