ITEMS               STANDARDS        RESULTS

Appearance:          white powder         WHITE POWDER

Na2S2O5 :                         97%MIN       

Clarity:                               slight turbid        

As :                                      <0.0005%        

Pb :                                      <0.001%        

Fe :                         <0.005%             

WATER INSOLUBLE MATTERS:    <0.05%    

PH:                                       4.5

Property: white or light yellow crystal powder, a strong smell of sulfur dioxide,relative density is 1.4, easy to dissolve in water and glycerin, water solution. It has acidity,and its solubility will become large while raising the temperature and is less to dissolve in ethanol.