as to checking that your purchased powder is indeed sodium chlorite, what to do if it doesn't pass the test as stated in Jim Humble's book part 2 (using the chlorine test strips) - ???
i purchased the powder, did the test, and it did not pass! it showed the clorine ppm OK, but showed chlorine also in the UN-activated beginning sample.... but then I tested a prepared solution(which i have been using successfully for weeks) purchased from a known-Jim Humble approved supplier, and it did not show zero-chlorine when diluted but unactivated either??/