QUALITY STANDARD: CHINA NATIONAL STANDARD GBT1887-1998 THE SPECIFICATIONS EXACT TESTING RESULT PURITY : 97.4% MIN 98.66% Na2CO2 : 1.7% MAX 0.68% MOISTURE : 0.4% MAX 0.20% PH VALUE : 8.6 MAX 8.27 NaCL : 0.3% MAX 0. 2% AS :0.0001MAX less than 0.0001 Pb 0.0005MAX less than 0.0005 Fe : 0.01 MAX 0.01 ASH : 0.1%MAX 0.01 Ca : 0.4 MAX 0.2