Item (indirect method)	First grade
ZnO dry	99.7min
Pb	0.037max
Mn	0.0001max
Cu	0.0002max
Insoluble in hydrochloric acid	0.006max
Loss on ignition	0.2max
Screen residues(through 45 micron wet screen)	0.1max
Volatile( 105 degree Celsius)	0.3max