1.crystal
2.food grade low heavy metal

Phosphorous acid 99.0%
Appearance:white crystal

Assay:99.0%min,

Fe:0.003%max,

PO4:0.20%max,
SO4:0.005%max  Cl:0.005%max
Packing:25kgs plastic woven bag, 24MTs/20'FCL 

Molecular Formular:H3PO3,

Molecular Weight:82

In industry and agriculture
The most important use of phosphorous acid is the production of phosphonates which are used in water treatment. Phosphorous acid is also used for preparing phosphite salts, such as potassium phosphite. These salts, as well as aqueous solutions of pure phosphorous acid, have shown effectiveness in controlling a variety of microbial plant diseases, in particular, treatment using either trunk injection or foliar containing phosphorous acid salts is indicated in response to infections by phytophthora and pythium-type plant pathogens (both within class oomycetes, known as water molds), such as dieback/root rot and downy mildew.Anti-microbial products containing salts of phosphorous acid are marketed in Australia as 'Yates Anti-Rot'; and in the United States of America, for example, aluminum salts of the diethyl ester of phosphorous acid (known generically as 'Fosetyl-Al') are sold under the trade name 'Aliette'. Phosphorous acid and its salts, unlike phosphoric acid, are somewhat toxic and should be handled carefully.

As a chemical reagent
Phosphorous acid is used in chemical reactions as a reducing agent that is somewhat less vigorous than the related hypophosphorous acid.
)Phosphorous acid is also used for preparing phosphite salts, such as potassium phosphite, ammonium phosphite and calcium phosphite. These salts, as well as aqueous solutions of pure phosphorous acid, have shown effectiveness in controlling a variety of microbial plant diseases, in particular, treatment using either trunk injection or foliar containing phosphorous acid salts is indicated in response to infections by phytophthora and pythium-type plant pathogens (both within class oomycetes, known as water molds), such as dieback/root rot and downy mildew. Anti-microbial products containing salts of phosphorous acid are marketed in Australia as 'Yates Anti-Rot'; and in the United States of America, for example, aluminum salts of phosphorous acid (known generically as 'Fosetyl-Al') are sold under the trade name 'Aliette'. Another important phosphite salt is lead phosphite dibasic which is used as PVC stabilizer.
3)Phosphorous acid is also used in chemical reactions as a reducing agent that is somewhat less vigorous than the related hypophosphorous acid.
4)Upon heating to around 200 °C, it is a convenient precursor to phosphine: 4H3PO3 → PH3 + 3H3PO4