TOYOPEARL HW-40S resin is a hydroxylated methacrylic polymer for size exclusion chromatography. TOYOPEARL HW-40S resin has a 5 nm pore size and a 30 µm bead size. Surface hydroxyl groups render this resin very hydrophilic, therefore minimal non-specific adsorption occurs, making the TOYOPEARL HW-40S resin useful for protein separations. TOYOPEARL HW-40S is typically used for size exclusion chromatographic separations of molecules though it can also be used for buffer exchange operations and to remove surfactants such as Triton X100 from protein solutions. It is often used for smaller biomolecules with exclusion limits up to 10,000 Da.
 
The good mechanical stability of the TOYOPEARL HW-40S resin produces good flow characteristics in large industrial size columns (up to 0.3 MPa). TOYOPEARL HW-40S resin is chemically stable from pH
2-14, and it is this stability that allows a constant packing volume over a wide range of salt concentrations and cleaning in place (CIP) with acid or base. Also, this resin can be run at elevated temperatures (4 - 60 °C) and is autoclavable at 121 °C.

If lower resolution is needed, the TOYOPEARL HW-40F resin can also be used for process SEC. For desalting, where the resin is used in a filtration mode to remove the target from a buffer, TOYOPEARL HW-40EC and TOYOPEARL HW-40C should be used due to their better flow dynamics and lower operating pressures.