Germanium In Waters Research Articles

Chitosan functionalized with di-2-propanolamine: Its application as solid phase extractant for the determination of germanium in water samples by ICP-MS

Cross-linked chitosan was chemically modified with di-2-propanolamine via an arm of chloromethyloxirane (CCTS-DPA resin). The adsorption behavior of the resin towards 62 elements was examined using a mini-column pretreatment method, and the collected elements were eluted with 1molL−1 nitric acid before measurement by inductively coupled plasma-mass spectrometry (ICP-MS).The CCTS-DPA resin can adsorb several metal cations and several oxoanionic elements at appropriate pH. However, di-2-propanolamine (DPA) attached to cross-linked chitosan (CCTS) showed excellent ability and selectivity for the adsorption of germanium at pH 6 to 9. The adsorption capacity of the resin for germanium (IV) was found to be 106mgg−1 resin, whereas the adsorption rate constant was 9.82×10−2min−1. Through the column treatment, alkali and alkaline earth matrices in river water and seawater matrices could be completely removed. The resin can also successfully remove chloride and selenium that can interfere with the direct determination of germanium by ICP-MS. The applicability of the CCTS-DPA resin was further demonstrated for the collection/preconcentration of germanium in environmental water samples and its determination by ICP-MS. The concentrations of germanium in tap water, river water and seawater samples were found in the range of 0.011 to 0.022μgL−1.

Electrothermal atomization laser-excited atomic fluorescence spectrometry for direct analysis of germanium in water and blood samples

Laser-excited atomic fluorescence spectrometry using a copper vapor laser as the excitation source has been used to develop a very sensitive method for direct determination of ultratrace amounts of germanium. For more efficient sample atomization, a graphite furnace was employed. Two excitation-detection schemes were evaluated. The best conditions for the analysis of germanium in water and blood are described. The effect of matrix modifiers and some possible interferences are reported. Absolute limits of detection of 0.7 pg (3σ) with a precision of 3.5% at the 2 ppb level for water samples and 1.0 pg (3σ) with 8.0% precision at the 2 ppb level for blood samples were achieved with no need for preconcentration.

Pre-concentration by coprecipitation. Part 1. Rapid method for the determination of ultra-trace amounts of germanium in natural waters by hydride generation–atomic emission spectrometry

A rapid method for the determination of ultra-trace amounts of germanium in sea-water, surface water and ground-water has been developed. This method initially involved coprecipitation of gallium and magnesium with hydroxide ions. Subsequent investigations have shown that gallium is unnecessary for quantitative recovery if calcium and carbonate ions are added with the magnesium and the precipitation is carried out at a high pH. The formation of a rather coarse precipitate aids in the filtration step, by reducing the filtration time from hours to minutes without any loss of analyte. The control of pH is crucial to the successful use of this method. Concentrations of germanium in waters have been determined by hydride generation atomic emission spectrometry, with a detection limit for the method of 0.6 pg ml–1(3σ) for a 1 l sample. Determinations of germanium concentrations in ground, sea and surface waters range from 0.5 to 17 pg ml–1(3 l sample). Initial experiments into the application of the method to samples spiked with 20 ng ml–1 concentrations of copper, colbalt, nickel and zinc have proved to be effective.

Electrothermal Atomic Absorption Spectrometric Determination of Germanium by Coprecipitation with Hafnium Hydroxide

Various trace amounts of germanium in water were concentrated by the Coprecipitation technique with hafnium hydroxide, and determined by graphite furnace atomic absorption spectrometry. At pH 7.5-10.5, hafnium hydroxide coprecipitates almost completely 0.3-10μg of germanium from pure solution (less than 200ml) and more than 80% of germanium from natural waters (less than 200ml). The atomic absorbance of germanium is increased about 6 times by the presence of hafnium. The calibration curve is linear from 12 to 400ng ml-1 of germanium. The detection limit (signal/noise=2) was 0.3ng ml-1 of germanium in 200ml of the initial pure solution. This method was successfully applied to the determination of germanium in spring water, using the standard addition method.

Electrolytic Etching of Germanium in Water

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The Reaction of Germanium with Aqueous Solutions: I . Dissolution Kinetics in Water Containing Dissolved Oxygen

The dissolution of germanium in water was studied as a function of oxygen partial pressure, temperature, crystallographic‐orientation, and mobile‐carrier density. It was found that, although thermodynamically feasible, germanium does not react with water, freed of oxygen, in the temperature range studied (up to 100°C). In the presence of oxygen the dissolution rate in pure water is a function of oxygen partial pressure, reaching a limiting value of the order of 1 µg/cm2/hr at 35°C under oxygen partial pressures greater than approximately 0.5 atm. For a given oxygen pressure the dissolution rate is approximately trebled for a ten ‐degree temperature rise, the measured activation energy for the dissolution reaction being . The order of dissolution rates for the three principal crystallographic faces was found to be . No effect on the dissolution rate was found to result from changes in mobile ‐carrier concentrations brought about by doping or illumination. From dissolution rates and potentials it is concluded that the dissolution process is under cathodic control and that the rate‐determining step is the reduction of oxygen by germanium.