The solid-phase extraction (SPE) technique has increasingly
become popular in comparison with the more
traditional liquid-liquid extraction methods because of its
several major advantages such as: (i) simple to operate; (ii)
high preconcentration factor; (iii) rapid phase separation;
and (iv) the ability to combine with different detection
techniques. Various solid phases including Chelex 100,
Amberlite XAD resins, synthetic polymers, polyurethane
foam, and activated carbon have been used for the solid
phase extraction of trace heavy metals in environmental
samples prior to their instrumental analysis. Among
solid-phase adsorbents, SDS coated alumina are very useful
for preconcentration and separation of metal complexes
because of good physical properties such as
their porosity, uniform pore size distribution, high surface
area as chemical homogeneous non-ionic structures, and
good adsorbent properties for great amounts of uncharged
compounds.