Appearance Clear colorless viscous liquid Assay Min 99% Weight/ mL at 20°C 1.115 - 1.117 g Refractive index (20°C; 589 nm) 1.446 - 1.447 Water (H2O) Max 0.2% Sulphated ash Max 0.01% Copper (Cu) Max 0.00005% Iron (Fe) Max 0.00005% Lead (Pb) Max 0.00005%