Patent ID: 8076155

Claim:
A method comprising: mixing a sample of a use composition with at least one reagent, the use composition comprising a concentration of a peracid and a concentration of a peroxide; delivering the sample mixture to an optical cell; selecting a wavelength for analyzing the sample mixture based on at least one of an estimated concentration of the peracid or an estimated concentration of the peroxide, wherein the wavelength is selected from at least a first wavelength associated with a first estimated concentration of the peracid or a first estimated concentration of the peroxide, and a second wavelength associated with a second estimated concentration of the peracid or a second estimated concentration of the peroxide, wherein the second wavelength is greater than the first wavelength, the second estimated concentration of the peracid is greater than the first estimated concentration of the peracid, and the second estimated concentration of peroxide is greater than the first estimated concentration of peroxide; measuring an optical response of the sample mixture in the optical cell at the selected wavelength, thereby obtaining response data indicative of absorbance of the sample mixture as a function of time; and determining the concentration of the peracid and the concentration of the peroxide in the use composition based on the response data wherein the first estimated peracid concentration is between 100 parts per million (ppm) and 1000 ppm and the first estimated peroxide concentration is between 100 ppm and 5000 ppm, or the second estimated peracid concentration is between 1000 ppm and 5000 ppm and the second estimated peroxide concentration is between 5000 ppm and 40,000 ppm.