In this study, effect of noble metal ions (Au, Ag and Cu) on the synthesis of metal nanoclusters (MNCs) have been investigated. Through heating at 70ºC, TSA/BSA–Au, –Ag and –Cu NCs were separately prepared from Au3+, Ag+ and Cu2+ respectively in the presence of bovine serum albumin (BSA) and thiosalicylic acid (TSA). They exhibit photoluminescence (PL) at 700, 624 and 430 nm, with an average life times of 1500, 100 and 11.71 ns, respectively, when excited at 350 nm. X–ray photoelectron spectroscopy (XPS) data support the presence of metal core (M0) and metal–thiolate shell (Mn–SRm) in each of the TSA/BSA–Metal nanoclusters (MNCs). Spectroscopic measurements reveal the formation of Au32–SR, Ag9–SR and (Cu4–Cu13)–SR species in the TSA/BSA–Au, –Ag and –Cu NCs respectively. Through PL quenching of the TSA/BSA–Au, –Ag and –Cu NCs, they have been used separately for quantitation of Hg2+, As3+ and Cr6+ , with linear ranges of 1400, 418, and 40400 nM and limits of detection (LODs) of 0.25, 2.34 and 3.54 nM, respectively. The PL quenching is mainly due to aggregation of the MNCs via metal–metal or metal–thiol interaction. The stable TSA/BSA–Au, –Ag and –Cu NCs have been employed separately for the determination of the concentrations of Hg2+, As3+ and Cr6+ ions in the spiked sea water samples, showing advantages of simplicity, rapidity, high selectivity, and sensitivity.
NATURAL CLEANING OF OIL POLLUTED SEASHORES