Item	Premium Grade	First Grade	Second Grade
Appearance	Pure White Crystal	White Crystal	White Crystal
Assay	99.0%min	99.0%min	98.5%min
Iron (Fe)	0.0001%max	0.0005%max	0.002%max
Chloride (C)	0.0005%max	0.0005%max	0.002%max
Sulphate (SO4)	0.0001%max	0.0005%max	0.002%max
Phosphate (PO4)	0.05%max	0.1%max	0.2%max
Plumbum (Pb)	0.0001%max	0.0001%max
Cadmium (Cd)	0.0001%max	0.0001%max
The test of 70% concentration water solution	Ftu0.1max	Ftu 1max
	Apha 3max	Apha 10max
Caution: second grade phosphorous acid is made from by-products of dimethyl phosphite.