... puirity grade; USP35; Analytical grade assay: 99.3%min. 10kg/bag or 1kg/bottle; nice quality ... Pb),ppm ≤10Antimony(Sb),ppm ≤50Arsenic(As),ppm ≤3Fluorine (F),% 22.3-25.5Mercury (Hg), ppm ≤2Iron (Fe), ppm ≤10pH ... (0.4% water solution) 2.8-3.5Loss on drying (105°C, 4h),% ≤0.2Whiteness ( ... 70-90μm particle size), % ≥98.0Transmissivity (3% water solution), % ≥95.0 high purity Stannous fluoride