All vapors are gases, but not all gases are vapors. For a vapor, changes in pressure or temperature can allow the vapor to change to a liquid (condense). Distinctly different from a gas or vapor, an aerosol is a fine dispersion of liquid droplets. For hydrogen peroxide disinfection and sterilization processes, the control of temperature, pressure, sterilant delivery, and vaporization method is critical to ensure the gaseous hydrogen peroxide is delivered and maintained as intended (eg, at or below the condensation point) for an efficacious process.
molecule, an atom, or an ion) and damage to these molecules will have dramatic effects on their structure and function, which culminate to give biocidal activity. Oxidation reactions with biocides have been shown to cause macromolecular unfolding, fragmentation, and crossreaction with oxidized groups.8 Proteins, carbohydrates, and lipids on the surface of microorganisms are particularly accessible targets, followed by various intercellular components, including proteins and nucleic acids, as the structure of the microorganism disintegrates.
As shown in Table 32.2, the D-value for three spore species was evaluated at different hydrogen peroxide liquid and vapor concentrations (250 000 and 1.5 mg/L, respectively). Even at the concentration of 1.5 mg/L hydrogen peroxide, the gaseous sterilant has a faster D-value than aqueous hydrogen peroxide at 250 000 mg/L.
TABLE 32.1 Classification of microorganism resistance and identification of microorganisms for which gaseous hydrogen peroxide efficacy has been demonstrated