Arsenic of natural or industrial origin often occurs in water and makes it impotable. Due to its high toxicity, very sensitive detection is required. In the present study an ultra-sensitive arsenite (As3+) sensing is reported, based on aggregation-aided surface-enhanced Raman scattering (AA-SERS) of modified silver colloids. SERS intensity of mercapto-compounds attached to the colloidal silver nanoparticles surface is greatly increased in the presence of arsenic. Colloid aggregation is facilitated by cross-linking; a meshwork consisting of arsenic atoms and glutathione bridges is formed, as indicated by UV-Vis absorption spectroscopy, TEM and Raman imaging. The best 2-mercaptopyridine reporter molecule makes it possible to directly detect As3+ at concentrations as low as 0.5 ppb, which is better than achieved by the SERS technique so far.

Department of Analytical Chemistry Faculty of Chemical Engineering University of Chemistry and Technology Technická 5 16628 Prague 6 Czech Republic; Institute of Organic Chemistry and Biochemistry Czech Academy of Sciences Flemingovo náměstí 2 16610 Prague 6 Czech Republic

Institute of Organic Chemistry and Biochemistry Czech Academy of Sciences Flemingovo náměstí 2 16610 Prague 6 Czech Republic

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