method that facilitates sensitive biopolymer characterization is disclosed . post - column fluorescence detection is uniquely suitable for dynamically labeled biopolymers such as protein . detection sensitivity has been enhanced by adding fluorescent stain and organic modifier to non - gel sieving matrix and by increasing the viscosity of sheath fluid . a detection limit better than silver staining is possible using the method according to the present invention . throughput may be increased by parallel operation of capillary array or an array of sheath flow cuvettes .