High activity, 50-200 µm particle size range alumina, available in acidic, neutral and basic surface pH options. The surface of the alumina can absorb molecules by interaction with the aluminium metal center, hydrogen bonding with surface hydroxyl groups, or by ion exchange if the surface carries a charge. The extent of these interactions can be enhanced by control of the surface pH with acidic, basic or neutral solutions.
Acid washing results in a surface with decreased capacity for basic compounds. Compounds are retained by ion exchange with the positively charged surface, or by specific interactions with the metal center.
Neutral surface allows interactions of the aluminium metal center with compounds whose heteroatoms are electronegative (e.g. N, O, P, S), or whose highly aromatic structure make them 'electron rich'. The adsorbent can be useful for retaining amines and aromatic compounds from aqueous or non-aqueous solvents.
Washing this amterial with a basic solution results in a net negative charge. Cationic compounds are retained on the negatively charged surface or by specific interactions with the metal center.
ISOLUTE® Al-A, AL-N and AL-B are available in a wide range of SPE column formats.