Dyed microspheres for characterization of photochemical reactor behavior

A method for measuring ultraviolet dose exposure in a photochemical reactor, comprising the steps of:

• a. introducing a plurality of unirradiated dye molecules attached to a microsphere into a photochemical reactor;
• b. exposing the unirradiated dye molecules to an ultraviolet radiation at a first wavelength effective to photochemically convert at least a portion of the unirradiated dye molecules to fluorescent dye molecules attached to the microsphere within the photochemical reactor;
• c. irradiating the fluorescent dye molecules at a second wavelength effective to cause fluorescence of the fluorescent dye molecules at a third wavelength;
• wherein the unirradiated dye molecules not photochemically converted to the fluorescent dye molecules when exposed to the first wavelength do not fluoresce at the third wavelength when irradiated with radiation at the second wavelength;
• d. detecting the fluorescence of at least a portion of the fluorescent dye molecules at the third wavelength;
• and
• e. correlating at least a portion of the fluorescence detected at the third wavelength to an ultraviolet radiation dose distribution from the photochemical reactor, the ultraviolet radiation dose distribution representing a plurality of fractions of the unirradiated dye molecules that received correspondingly different ultraviolet dose exposures to the ultraviolet radiation including at least the portion that were converted to the fluorescent dye molecules, the ultraviolet dose exposure is defined as the time-integral of ultraviolet intensity history over a period of exposure;
• wherein the unirradiated dye molecule is attached to the microsphere in a manner that does not substantially diminish the fluorescence of the fluorescent dye molecules at the third wavelength so as to allow for quantifiable detection of the fluorescence,
• wherein the microsphere is coated with streptavidin, the unirradiated dye molecule is attached to the microsphere by a chemical structure of the formula:
• M-S—B-L-D,
• wherein:
• M represents the surface of the microsphere,
• —S represents the streptavidin attached to the surface of the microsphere,
• —B represents a biotin molecule attached to the streptavidin;
• —L represent a hydrophilic linking group;
• —D represents the dye molecule according to a formula of: