NOVELTY - A spherical, brightly fluorescing, non-sticking chemical composition of predetermined, definitive and uniform size of 15 nm to 50 microns, engineered to glow brightly when exposed to ultraviolet light, capable of characterizing microscopic defects in membranes, comprises: a) a nanoparticle selected from silica or silesquioxame; and b) a fluorescent, bridged silane monomer (I) capable of being incorporated into the nanoparticle via a modified Stober process.    USE - As spherical, brightly fluorescing, non-sticking chemical composition, engineered to glow brightly when exposed to ultraviolet light, useful for characterizing microscopic defects in membranes made from a material selected from fluorinated polymers, non-fluorinated, non-polar materials, and non-fluorinated, polar materials (claimed), where the microscopic defects in membranes include pinholes, cracks or fissures; and the membranes are useful in commercial and industrial applications such as water purification via filtration or reverse osmosis, food and drug processing, and energy-related applications like battery and fuel cell technology.    ADVANTAGE - The chemical composition enables rapid and cost-effective characterization (identification and location) of microscopic defects in membranes such as pinholes, cracks or fissures. Thus the compositions have wide spectrum applicability on a number of different types of porous and non-porous membranes that are used for diverse applications in various industries. The method of characterizing microscopic defects in membranes using the spherical, pure fluorescent chemical composition allows rapid, simple and highly accurate integrity tests to be performed on membranes used in a variety of filtering, purification or manufacturing processes. The composition comprises brightly fluorescing silica or silsesquioxane spheres prepared with pre-determined definitive and uniform sizes ranging from 15 nanometers (nm) and up to 50 microns (50000 nm, or the thickness of a human hair). The spheres of uniform controlled size allow them to be used to characterize defects or holes in membranes based on a size exclusion mechanism. The spheres are engineered to glow brightly when exposed to ultraviolet light in order to allow visual or highly sensitive fluorescence spectroscopy or microscopy to characterize the passage of the particles through defects or holes in a membrane and even identify where the defect is located (by the residence of fluorescence particles on the membrane). If the spheres in a liquid carrier pass through a microscopic defect or hole in a membrane, they will generate a distinct fluorescent glow, which acts as an optical signature in the liquid that passes through the membrane. The intensity of the fluorescence corresponds to the magnitude and/or number of defects. The pre-determined size and color of the spheres provide a quantitative indication of the size of the defect. The differently sized spheres can be manufactured in multiple distinct colors (e.g., blue, violet, orange, yellow, green) using the different fluorescent dyes, which allows for a faster and simpler test protocol. Multiple simultaneous tests can take place using the different sized particles each with a different color (color coded spheres of different sizes), where a particular color corresponds to a particular size. Such method allows much simpler, visual testing, location and characterization of membrane defects. The method of characterizing defects in membrane utilizes food and drug-safe fluorescent dyes of particular color which (in addition to the inert materials of the spheres, themselves) enhances the utility of the method in food and drug processing applications. The silica nanoparticle encapsulation of such colored fluorescent additives eliminates the need for subsequent sterilization and cleaning equipment following characterization of defects in a membrane being used as part of a particular food or drug processing protocol.    DETAILED DESCRIPTION - A spherical, brightly fluorescing, non-sticking chemical composition of predetermined, definitive and uniform size of 15 nanometers to 50 microns, engineered to glow brightly when exposed to ultraviolet light, capable of characterizing microscopic defects in membranes, comprises: a) a nanoparticle selected from silica or silesquioxame, where the nanoparticle is prepared by the sol-gel polymerization of tetramethoxysilane and tetraethoxysilane for silica nanoparticles; and the two starting materials selected from methytrimethoxysilane and methyltriethoxysilane; 1,4-bis(triethoxysilyl)benzene and 1,4-bis(trimethoxysilyl)benzene; 1,1-bis(triethoxysilyl)methane and 1,1-bis(trimethoxysilyl)methane; 1,2-bis(triethoxysilyl)ethane and 1,2-bis(trimethoxysilyl)ethane; 1,2-bis(triethoxysilyl)ethene, and 1,2-bis(trimethoxysilyl)ethene; 1,6-bis(triethoxysilyl)hexane and 1,6-bis(trimethoxysilyl)hexane; 1,8-bis(triethoxysilyl)octane and 1,8-bis(trimethoxysilyl)octane; and 1,8-bis(triethoxysilyl)3,3,4,4,5,5,6,6-octafluorooctane and 1,8-bis(trimethoxysilyl)3,3,4,4,5,5,6,6-octafluorooctane for silsesquioxane nanoparticles; and b) a fluorescent, bridged silane monomer with the general chemical structure of (R'O)3Si-R1-Si(OR')3 (I), capable of being incorporated into the nanoparticle via a modified Stober process.    R'=methyl or ethyl;and    R1=fluorescent organic group.    INDEPENDENT CLAIMS are included for the following:    (1) synthesizing the spherical, brightly fluorescing chemical composition in pure state, involving: incorporating a silane monomer into a silica matrix through a modified Stober process, where the modified Stober process involves the steps of mixing the monomer with excess water and ammonium hydroxide in ethanol, resulting in nanoparticles of a pre-determined size; confirming the size of the resulting nanoparticles using dynamic light scattering; and centrifuging the resulting nanoparticles to remove excess monomer; and    (2) method to characterize microscopic defects in membranes using the spherical, pure fluorescent chemical composition involving: introducing the chemical composition into a membrane filtration system; detecting passage of the nanoparticles through the membrane using a detection method selected from visual inspection, fluorescence spectroscopy and microscopy; and if passage is detected, then introducing chemical compositions of progressively larger sized into the membrane filtration system in order to define the upper limits of the defect's size.