Detection of Attomolar Concentrations of Alkaline Phosphatase by Capillary Electrophoresis Using Laser-Induced Fluorescence Detection

Alkaline phosphatase can be assayed by monitoring the conversion of the fluorogenic substrate AttoPhos into the highly fluorescent product AttoFluor. We have used capillary electrophoresis with laser-induced fluorescence detection to monitor this reaction. The concentration limit of detection (3σ) of alkaline phosphatase is 1.5 × 10 - 17 M (2.1 fg/mL), which corresponds to a mass limit of detection of nine molecules (1.5 × 10 - 23 mol) contained within a 1-μL sample volume.