A monolith-like macroporous reversed phase/anion exchange mixed-mode adsorbent sintered with a polyethylene powder for solid-phase extraction

A monolith-like continuous macroporous adsorbent sintered with a reverse-phase/anion exchange-type polymer and a polyethylene powder was prepared for solid-phase extraction (SPE). The sintered SPE adsorbent showed high permeability, which was equal to that using bulk adsorbent. Several drugs such as caffeine and acetaminophen could be extracted quantitatively even at 30 mL min^-1 of a sample flow rate. Neutral and basic drugs, such as acetoaminophen, caffeine, theobromine, atenolol, procaine and procainamide, were clearly retained by hydrophobic interaction; they were quantitatively eluted with methanol. Acidic drugs, such as acetylsalicylic acid, naproxen and salicylic acid, were strongly retained by both a hydrophobic interaction and an anion exchange interaction. The acidic drugs retained were not eluted with only methanol, whereas they were quantitatively eluted with methanol containing 1 % of formic acid. The sintered SPE adsorbent could produce an ion-exchange interaction effectively without any influence based on the water repellency of polyethylene. The monolith-like macroporous SPE adsorbent is easy to handle and is useful for the SPE of drugs and the other compounds. Additionally, the sintering technique using a bulk adsorbent and a polyethylene powder would be applicable to the preparation of SPE adsorbents having various shapes.