The world’s first multi-angle light scattering (MALS) detector that can be coupled to any UHPLC system in order to determine absolute molecular weight and size distributions of polymers, peptides, and proteins directly, without resorting to column calibration or reference standards. With interdetector broadening of just a few µLs, a µDAWN™/Optilab® UT-rEX™ µSEC-MALS system can accurately analyze the molar mass and size of UHPLC peaks without loss of resolution.