Control of gaseous hydrogen peroxide concentration during sterilization

A method of continuously controlling the concentration of gaseous hydrogen peroxide in a sterilization chamber to provide at least a precalculated concentration of said gaseous hydrogen peroxide comprising:

• a) measuring the concentration of gaseous hydrogen peroxide in the sterilization chamber by
• i. obtaining the near infrared spectrum of a series of calibration samples containing known concentrations of hydrogen peroxide vapor, water vapor, and combinations thereof over the region from about 900 to about 2000 nanometers;
• ii. establishing a correlation between the series of near infrared spectra of said calibration samples obtained in part i. and the known concentrations of gaseous hydrogen peroxide in said calibration samples using a multivariant statistical technique;
• iii. obtaining the near infrared spectrum of a gaseous sample from the sterilization chamber over the said region of part i.;
• and
• iv. applying the multivariant statistical technique to the near infrared spectrum of the gaseous sample to calculate the concentration of gaseous hydrogen peroxide therein, thereby affording a measured concentration of gaseous hydrogen peroxide;
• b) comparing the measured concentration of gaseous hydrogen peroxide with said precalculated concentration;
• and
• c) automatically adding additional gaseous hydrogen peroxide to the sterilization chamber when said measured concentration of gaseous hydrogen peroxide is less than said precalculated concentration.