Based on Resonant Acoustic Profiling (RAP) technology, RAPid 4 enables real-time label-free measurement and analysis of biomolecular interactions with accuracy, reproducibility and sensitivity. The flow-based system reduces the need to purify samples and generates accurate kinetic, affinity and concentration measurements from complex mixtures, such as cell culture supernatants and periplasmic extracts. A stand-alone, fully automated platform, the system requires minimal user intervention and is controlled via user-friendly software, typically processing an average of 400 samples per day. RAP measures the oscillation of a resonating quartz crystal, which decreases in proportion to the mass of the molecules binding to its surface. Researchers interrogate and evaluate the data using Workbench software package.