Items	Super Grade	Standard grade.
Sodium Hydroxide %≥	99.5	99.0
Sodium Carbonate%≤	0.5	0.8
Sodium Chloride %≤	0.045	0.050
Ferroso-ferric Oxide %≤	0.004	0.004
Silicon Dioxide %≤	0.004	0.006
Sodium Sulfate %≤	0.050	0.060
Copper %≤	0.0002	0.0003
Calcium %≤	0.005	0.008