The 6 cc Oasis WAX cartridges contain the Oasis WAX sorbent, which is a polymeric reversed-phase, weak anion exchange mixed-mode sorbent that has been optimized for fast, simple, and highly selective sample preparation of strong acidic compounds. Since the Oasis WAX sorbent is water wettable, it maintains its capability for higher retention and excellent recoveries even if the sorbent runs dry, which means there is no need to take extraordinary steps to keep the sorbent beds from drying out during the critical steps prior to sample loading.