Ontwsep™ HLB is a sorbent composed of polystyrene/divinylbenzene and pyrrolidone groups. Its surface contains both hydrophilic and lipophilic groups, resulting in a generally balanced adsorption effect on a variety of polar and nonpolar molecules. The pH range of usage is 1.0 to 14.0. It offers significantly better adsorption and sample capacities than C18 (3–10 times greater). Many highly hydrophilic chemicals that are difficult to retain on C18 columns perform well on Ontwsep™ HLB.

It is commonly used for the extraction, enrichment, and purification of various chemicals in industries such as food testing, environmental testing, and biological sample analysis.