ITEM	INDEX
	US USP (24)	Food grade	Industry grade
Assay	≥ 98 %	> 99 %	> 98.0 %
Drying loss	≤ 2.0 %	< 1.0 %	< 1.5 %
Heavy metal	≤ 20 PPM	< 20 PPM	< 20 PPM
Sulphate	≤ 0.05 %	< 0.05 %	< 0.05 %
Chloride	≤ 0.07 %	< 0.05 %	< 0.05 %
Reduzate	≤ 0.5 %	< 0.5 %	< 0.5 %
lead salt	≤ 10 PPM	< 10 PPM	< 10 PPM
Arsenic	≤ 3 PPM	< 3 PPM	< 3 PPM