Hello dear Researchers, please I need your help in the determination of the initial concentration(Co) of arsenic In my geopolymer. The purpose is to calculate the immobilization efficiency in order to do that I need Co. My raw materials have some arsenic content as background concentration 21. 8 ppm in fly ash and 151.9 ppm in mine tailings) and I have added three different percentage of sodium arsenate Na2HAsO4.7H2Oas sources of arsenic (0.01% 0.03% 0.05%). Thank you in advance for efforts.