Abstract: A method and apparatus for assay sample volume normalization for a fluid sample applied to a diagnostic assay membrane to confirm the application of the sample fluid. The method can be used in manual, semi-automated, and automated analyser systems by applying a volume of a fluid sample having a fluorescence disruptor to a sample addition area of a membrane of an assay device having a fluorescent reporter and quantifying the change in fluorescence. Confirmation of sample fluid deposit and sample fluid volume calculation can be done by imaging the sample addition area to detect the disruption to fluorescence in the deposit area prior to running an assay.