sentences:  Common spectroscopy detection techniques are refractive index (RI) and ultraviolet (UV).When eluting spectroscopically similar species (such as during biological purification), other techniques may be necessary to identify the contents of each fraction.It is also possible to analyse the eluent flow continuously with RI, LALLS, Multi-Angle Laser Light Scattering MALS, UV, and/or viscosity measurements.