Low-temperature sorption-luminescence determination of copper in natural water using silica gel chemically modified with mercapto groups

Silica gel with mercaptopropyl groups chemically bonded to its surface extracts copper from solutions with pH 2-9 with a recovery of 99.9%; the sorption equilibration time is no longer than 5 min. Ultraviolet irradiation of wet sorbates cooled to the liquid nitrogen temperature (77 K) generates yellow-orange luminescence (λmax = 585 nm), which was used as the analytical signal for the development of a procedure for the low-temperature sorption-luminescence determination of copper. The detection limit is 0.08 μg per 0.1 g of the sorbent. The determination of copper is unaffected by the interference from 1 04-fold amounts of Zn(II), Cd(II), Mn(II), Ni(II), Co(II), Ca(II), Mg(II), and Al(III); 103-fold amounts of Fe(III); 30-fold amounts of Bi(III); tenfold amounts of Ag(I); and fivefold amounts of Cr(VI). The procedure was used for the determination of copper in natural water.