Three different concentrations of sodium hypochlorite were
prepared from a solution (6% v/v) of ultra germicidal bleach (Food
Services America, Inc., Seattle, WA). Sterile water was mixed with
sodium hypochlorite to have a final concentration of 50, 100 and
200 ppm (500 ml each). Chlorine concentration was verified with
LaMotte chlorine test papers (Chestertown, MD). The pH of the
chlorine solution was adjusted to 6.5 in accordance with CFSAN