Uop Lcc

Keith L Miller

Mark S Zetter

Terry R Todd

Rian Van Den Berg

On line and essentially continuous measurements of hydrogen peroxide vapor in the presence of water vapor can be made using near infrared (NIR) spectroscopy using fiber optic cables to transmit infrared radiation between, e.g, a sterilization chamber and the NIR instrument. Measurement of hydrogen peroxide concentration in the foregoing manner is incorporated into a control system which automatically adds gaseous hydrogen peroxide to the sterilization chamber when the measured concentration falls below a precalculated value. Such a control system ensures the presence in the sterilization chamber of an adequate concentration of gaseous hydrogen peroxide to effect sterilization throughout the sterilization procedure.

Control of gaseous hydrogen peroxide concentration during sterilization

On line and essentially continuous measurements of hydrogen peroxide vapor in the presence of water vapor can be made using near infrared (NIR) spectroscopy using fiber optic cables to transmit infrared radiation between, e.g, a sterilization chamber and the NIR instrument. Hydrogen peroxide absorbs selectively at about 1420 nm, where water vapor also absorbs, but the absorbance at 1420 nm can be corrected for water vapor measurements at remote wavelengths where H.sub.2 O.sub.2 is transparent. The measurement process may be conveniently made by applying a multivariant statistical technique to the spectrum obtained over one or more bands within the 900-2000 nm region using the correlation obtained for a calibration set for which analogous measurements are made over the same region.

Determining the concentration of gaseous hydrogen peroxide

On line and essentially continuous measurements of hydrogen peroxide vapor in the presence of water vapor can be made using near infrared (NIR) spectroscopy using fiber optic cables to transmit infrared radiation between, e.g, a sterilization chamber and the NIR instrument. Hydrogen peroxide absorbs selectively at about 1420 nm, where water vapor also absorbs, but the absorbance at 1420 nm can be corrected for water vapor measurements at remote wavelengths where H.sub.2 O.sub.2 is transparent. The measurement process also may be incorporated into a control system assuring optimum hydrogen peroxide vapor concentrations for the sterilization procedure.

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El Dorado Hills, CA, United States of America

Keith L Miller