Comparison of pH and cell density dependent killing efficacy of HSP, H₂O₂, and NaOCl Killing efficacy of biocides (20 ppm) at pH 7.0 on 10⁶<i>E</i>. <i>coli</i> (A), at pH 8.5 on 10⁶<i>E</i>.<i>coli</i> (B), and at pH 7.0 on 10³<i>E</i>. <i>coli</i> (C) as measured by total CFU/mL over 300 min (A,B) or 60 min (C).

<p>H₂O₂ is much slower at killing bacteria at pH 7.0 than either HSP or HOCl₂ (A). Raising the pH to 8.5 increases the 100% kill times of NaOCl to equal to or greater than that of HSP (B). At lower cell densities HOCl₂ reaches 100% killing in 15–30 minutes while both HSP and H₂O₂ show slower killing kinetics (C).