Patent ID: 8183052

Claim:
A method for testing the sterility of a sample comprising: (a) providing a filter device having a chamber and a filter configured to collect culturable organisms within the chamber; (b) filtering a sample through the filter such that any collected culturable organisms are retained on the filter within the chamber; (c) adding a culture medium to the chamber such that at least a portion of the collected culturable organisms are resuspended in the culture medium; (d) after a pre-determined period of time, irradiating a fluorescent species immobilized on a substrate with excitation light emanating from a probe physically isolated from the fluorescent species immobilized on the substrate, wherein the fluorescent species comprises a seminaphthofluorescein/human serum albumin conjugate, wherein the fluorescent species immobilized on the substrate is in liquid communication with the culture medium, wherein the excitation light has a wavelength sufficient to effect fluorescent emission from the fluorescent species, and wherein the fluorescent species exhibits a first emission intensity at a first emission wavelength and a second emission intensity at a second emission wavelength, the ratio of the first and second emission intensities being dependent on pH; (e) measuring the first and second emission intensities to determine the pH of the culture medium; and (f) inferring from the determined pH of the culture medium the sterility of the sample.