Novel chelating silicas for the preconcentration of ultratrace metals in natural waters

A variety of amino functional compounds were attached to silica particles through the use of a 3-glycidoxypropyltrimethoxysilane intermediary. The resultant amines were also converted to their dithiocarbamates. Characterisation of the immobilised functional groups was achieved and demonstrated the presence of a variety of different chemical structures on the silica surface. The functionalised silicas were subjected to a rapid and efficient screening tehcnique which defined their chelating properties and revealed three modifying agents, ethylenediamine N.N'bis dithiocarbamate, diethylenetriamine monodithiocarbamate and propan-l,3-diamine, which were subjected to more intense study. These three modifying agents were capable of preconcentrating copper, nickel, chromium, cobalt and cadmium in the 0.01-10 ug.l"1 range from estuarine water samples by a factor of 100 prior to determination by electrothermal atomic absorbtion.