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Rivelazione e determinazione indivuale di cromo(VI) e cromo(III), insieme a rame, piombo, nichel e zinco - in acqua potabile a livello di ppb.
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Individual detection and determination of Cr(VI) and Cr (III) - together with Cu, Pb, Cd, Ni and Zn - in tap water at ppb level.
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Preconcentration of analytes by aerosol deposition in graphite furnace atomic absorption spectrometry at pg g-1 level
No full textTrace, alkaline and alkaline elements in sea water samples from Ross Sea - Terra Nova Bay (Antarctica).
No full textThis report concerns the correlation of the analytical results relevant to some elements obtained in filtered sea water samples collected in Terra Nova Bay and the Ross Sea (Antarctica) during three Italian expeditions. The following ranges of variability of the medians of total concentrations (ng/l) - which include time effect among expeditions and bias effect among participant groups - were found for trace elements (single values refer to elements which were only determined once by one laboratory): Sb(260), As(1.2 10(3)), Cd(5-50), Cr(120), Co(4), Cu(110-230), Fe(435-445), Pb(6-52), Mn(15-88), Hg(3), Ni(185-580), Se(30) and Zn(242-265). Speciation studies pointed out that 10-40% of Cd, 15-60% of Cu and 20-50% of Pb were present in the samples as an ASV-labile fraction.
As for alkaline and alkaline-earth elements, the following concentration ranges in surface sea waters, expressed in mM, were found: Li([1.4-3.0]10(-2)), Na(394-480), K(5.1-9.9), Ca (6.4-14.7), Mg (46.2-59.0) and Sr ([7.6-10] 10(-2))
ELECTROCHEMICAL SPECIATION AND DETERMINATION OF ORGANOMETALLIC SPECIES IN NATURAL-WATERS
No full textBEHAVIOR OF SOME DIALKYL-LEAD AND TRIALKYL-LEAD COMPOUNDS IN THE HYDRIDE-GENERATION PROCEDURE USING A NONDISPERSIVE ATOMIC-FLUORESCENCE DETECTOR
No full textThe method of generating covalent hydrides by reduction with sodium tetrahydroborate was applied to aqueous solutions containing traces of R3Pb+ and R2Pb2+ compounds (R = methyl, ethyl). For each compound the effects of sample acidity, sodium tetrahydroborate and hydrogen peroxide concentrations, reaction-vessel and transfer-line materials, were measured and the experimental conditions defined for obtaining maximum sensitivity. Experimental evidence indicating the formation of organolead hydrides during the reduction step at room temperature was adduced. The reaction efficiency was found to be 90% for trimethyl-, triethyl- and diethyl-lead and 59% for dimethyl-lead. In the case of inorganic lead the efficiency was only 27%. Without an intermediate preconcentration step, the detection limits obtained for trimethyl-, triethyl-, dimethyl- and diethyl-lead (3 times the standard deviation) were 3-5 ng of lead per litre. A procedure for discriminating between R3Pb+, R2Pb2+ and Pb2+ compounds is proposed
Preliminary tests to select operating conditions for the accurate determination of stability constant by cation exchange chromatography: the Cd2+-Cl- and Cd2+-NO3- systems
No full textIon chromatography (IC) has been demonstrated to be a powerful tool for equilibrium constant determination, related to various cation-ligand systems. Nevertheless, no systematic research has been carried out to develop preliminary checks in order to verify whether the variation in ligand concentration in the eluent at constant ionic strength affects the exchange mechanism for the system of interest in the selected chromatographic column. In this paper, tests are proposed which allow one to determine beforehand the experimental conditions to be used in cation-exchange chromatography, whereby parallel mechanisms of elution (mainly in the reversed-phase mode) are avoided. In this way IC becomes an independent rather than an auxiliary means to obtain accurate βi values. Cd(II)Cl- and Cd(II)NO3 - systems were considered and are discussed
SIMULTANEOUS DETERMINATION OF ARSENIC, SELENIUM, TIN AND MERCURY BY NON-DISPERSIVE ATOMIC FLUORESCENCE SPECTROMETRY
No full textA procedure is described for simultaneous determination of arsenic, selenium, tin and mercury in aqueous solution by non-dispersive atomic-fluorescence spectrometry. Radiofrequency-excited EDLs, 100% modulated in the kHz region, were used for atom excitation. Sodium tetrahydroborate was used as reductant and a hydrogen-argon miniflame as atomizer. In the optimized procedure, which uses 1 ml of sample, the limits of detection (three times the standard deviation of the blank) were 0.04, 0.08, 0.1 and 0.1 ng ml for arsenic, selenium, tin and mercury respectively. The linear dynamic range was greater than three decades for all analytes and the precision was better than 7% (typically 3%) for concentrations ≥ 1 ng ml. Results for mutual interference effects are reported. Copper, nickel, lead and cobalt interfered only with selenium (5 ng ml), when present in at least 200-fold weight ratio to it. Using 5 ml of sample improved the limits of detection for selenium and arsenic (0.01 and 0.02 ng ml respectively), but at the expense of greater interference. Recovery from spiked natural water samples was better than 95% at the ng ml level, except for selenium in sea-water, when the recovery was only 85%. Determination of the four elements, including standard-addition and background measurements, requires about 10 min
DETERMINATION OF TRACE-ELEMENTS IN SEA-WATER SAMPLES FROM TERRANOVA BAY - ROSS SEA (ANTARCTICA)
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