Laser induced breakdown spectroscopy (LIBS) is applied to analyze aqueous solutions of Li(+), Na(+), Ca(2+), Ba(2+), Pb(2+), Cd(2+), Hg(2+) and Er(3+) and suspensions of ErBa(2)Cu(3)O(x) particles (d=0.2 microm). An excimer (308 nm) pumped dye laser with laser pulse at 500 nm and pulse energy at 22+/-2 mJ is used to produce plasma in aqueous solution. Plasma emission lines of the elements are detected by a photodiode array detector. Detection limits of the metal ions are 500 mg/l for Cd(2+), 12.5 mg/l for Pb(2+), 6.8 mg/l for Ba(2+), 0.13 mg/l for Ca(2+), 13 microg/l for Li(+) and 7.5 microg/l for Na(+). No mercury and erbium emission can be detected, even at Hg(2+) and Er(3+) concentrations of up to the g/l range. On the other side, for Er in suspensions of ErBa(2)Cu(3)O(x) particles a more than 10(3) times higher sensitivity is found than for dissolved Er(3+). This result gives a possibility to analyze colloid-borne metal ions with an increased sensitivity.

The system described allows the fully automated, efficient and rapid preparation of Ga-DOTA-derivatized peptides. It has been used successfully and reliably for routine preparations in clinical studies.

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The polyphosphate kinase gene from Pseudomonas aeruginosa was overexpressed in its native host, resulting in the accumulation of 100 times the polyphosphate seen with control strains. Degradation of this polyphosphate was induced by carbon starvation conditions, resulting in phosphate release into the medium. The mechanism of polyphosphate degradation is not clearly understood, but it appears to be associated with glycogen degradation. Upon suspension of the cells in 1 mM uranyl nitrate, nearly all polyphosphate that had accumulated was degraded within 48 h, resulting in the removal of nearly 80% of the uranyl ion and >95% of lesser-concentrated solutions. Electron microscopy, energy-dispersive X-ray spectroscopy, and time-resolved laser-induced fluorescence spectroscopy (TRLFS) suggest that this removal was due to the precipitation of uranyl phosphate at the cell membrane. TRLFS also indicated that uranyl was initially sorbed to the cell as uranyl hydroxide and was then precipitated as uranyl phosphate as phosphate was released from the cell. Lethal doses of radiation did not halt phosphate secretion from polyphosphate-filled cells under carbon starvation conditions.Biological methods for the removal of heavy metals and actinides have recently been investigated due to their cost effectiveness at moderate metal concentrations. Many strains have been isolated that sorb (14,23,51,59,61), reduce (10, 18, 52, 56), and precipitate (4, 33, 41, 44, 45) metals, usually on the outer membrane of the cell. Sorption is generally achieved in a reversible process and is dependent on the composition of the water being treated, as other chelating agents compete with the complexing moieties on the cell. Thus, the applicability of this method in more complex waste streams or environments may be somewhat suspect due to the relatively low binding affinities of cellular components for metals compared to chelators, such as humic or organic acids. Reduction is generally limited to anaerobic processes and is ineffective against single-oxidationstate metals. Precipitation has the advantage of producing chemically stable forms of metal, and its use is not limited to reducible metals.With respect to the biological precipitation of metals, both metal sulfides (12,57,58,60) and metal phosphates (4, 33, 45) have been investigated due to their low solubilities. While some work has been done to produce sulfide aerobically (57), its production is generally an anaerobic process, limiting its applicability. The release of phosphate via the hydrolysis of an organic phosphate has been shown to be an effective method for the precipitation of metals on cell membranes. Macaskie and Dean (30) isolated a cadmium-resistant strain of Citrobacter that precipitated numerous metals, such as uranyl ion, as metal phosphates through the use of a membranebound acid phosphatase (26,31,32). Using glycerol-2-phosphate as a phosphate source, the organism cleaved phosphate from the source in the periplasmic space, leaving it to bind with metals that had been complexe...

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