Development of superparamagnetic particles for analytical pre-concentration

Abstract

The very low levels of trace heavy metals and organic pollutants in water can present difficulties for the analytical chemist that can often be overcome by employing a pre-concentration method to enrich the analyte. Adsorbants and reactive solid phase materials can be used to scavenge analytes from the solution and to isolate them from interfering species. In this work Fe2O3 superparamagnetic nano-particles were covered with a chemically modified mesoporous silica layer, able to uptake the target analyte. The solid phase, with attached analyte, can then be easily isolated from the sample solution by the application of an external magnetic field. Two different types of nano-sized particles were synthesised by modification of the silica by silanization. 3- aminopropyltriethoxysilane was reacted with the –OH groups present on the surface and in turn its –NH2 groups were converted to dithiocarbamates. This type of particle was tested for copper extraction but was found to be unsuccessful due to the leakage of large quantities of iron into solution which competed with the analyte for the dithiocarbamate groups. Octadecyltrichlorosilane was reacted with the silica surface to give a second type of particle specialised in collecting organic pollutants. Recoveries above 80% were obtained extracting polycyclic aromatic hydrocarbons and during a pilot experiment, 92% recovery of “tributyltin” was achieved

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Identifiers

ORCID for Andrew L. Hector: orcid.org/0000-0002-9964-2163

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