≤0.01% Mg, alkaline earth metals (as Ca)
acidity or alkalinity, complies
≤0.0001% potassium hexacyanoferrate(II)
≤0.005% in water insoluble matters
≤0.001% total nitrogen (N)
≤0.005% free alkali (as NaOH)
≤0.005% free acid (as HCl)
≤0.0003% heavy metals (as Pb)