Zerovalent copper nanoparticles (Cu 0 ) of 12 nm size were synthesized using an inert gas condensation method in which bulk copper metal was evaporated into an inert environment of argon with subsequent cooling for nucleation and growth of nanoparticles. Crystalline structure, morphology and estimation of size of nanoparticles were carried out by X-ray diffraction and transmission electron microscopy. The antibacterial activity of these nanoparticles against the Gram-negative bacterium Escherichia coli was assessed in liquid as well as solid growth media. It was observed from scanning electron microscopic analysis that the interaction of copper nanoparticles with E. coli resulted in the formation of cavities/pits in the bacterial cell wall. The antibacterial property of copper nanoparticles was attributed mainly to adhesion with bacteria because of their opposite electrical charges, resulting in a reduction reaction at the bacterial cell wall. Nanoparticles with a larger surface-to-volume ratio provide more efficient means for antibacterial activity.

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An analytical method has been developed for the preconcentration of rare earth elements (REEs) in seawater for their determination by inductively coupled plasma optical emission spectrometry (ICP-OES). An indigenously synthesized chelating resin was used for the preconcentration of (REEs) which was based on immobilization of fluorinated b-diketone group on solid support styrene divinyl benzene. Sample solutions (adjusted to optimized pH) were passed through a polyethylene column packed with 250 mg of the resin. Experimental conditions consisting of pH, sample flow rate, sample volume and eluent concentration were optimized. The established method has been applied for the preconcentration of light, medium and heavy REEs in coastal sea water samples for their subsequent determination by (ICP-OES). Percentage recoveries of La, Ce, Nd, Sm, Eu, Gd, Dy, Er, Yb and Lu were ³ 95%, a preconcentration factor of 200 times, and relative standard deviations < 5% were achieved.

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