Inorganic phosphate (Pi) is one of the most important ions in biological systems. It functions in a variety of roles. One of the most important roles is as a molecular switch, turning enzyme activity on and off through the mediation of the various protein kinases and phosphatases in biological systems. The Pi ion is also of great importance in mineralization processes and is a primary stimulus of algal blooms frequently found in bodies of fresh water, due to runoff from areas of high fertilizer use. The PicoProbe Phosphate Assay Kit provides an easy, quick and sensitive means of assessing phosphate over a wide range of concentrations. In the assay, inorganic phosphate will react with substrate and PicoProbe? to generate fluorescence (