Rubidium concentration

The principal rubidium salts which would probably have been present in the sediment (chloride, sulfate, bicarbonate, etc.) are all soluble in water. As discussed later, the red clay was thoroughly dialyzed prior to use (including prior to analysis by emission spectroscopy). Any rubidium salts initially present in the clay samples would, therefore, have been removed by the dialyzing solution. Hence, it was assumed that the rubidium concentration given in Table I represented sorbed rubidium which had been in equilibrium with the rubidium in the original interstitial seawater. Then when calculating distribution coefficients from experimental data, the concentration given in Table I was used as the initial clay-phase rubidium concentration, rather than zero as used with most of the other species studied. 

Whereas the abundance of Sr in rubidium rich rocks changes over time due to the radioactive 3 decay of Rb as a function of the primordial rubidium concentration and the age of the mineral, the... 

Whereas the abundance of Sr in rubidium rich rocks changes over time due to the radioactive 3 decay of Rb as a function of the primordial rubidium concentration and the age of the mineral, the abundance of the stable Sr isotope and consequently the Sr/ Sr is constant in nature. The constant Sr/ Sr isotope ratio is often used for internal standardization (mass bias correction) during strontium isotope ratio measurements of Sr/ Sr. In the rubidium-strontium age dating method, the isotope ratios Sr/ Sr and Rb/ Sr are measured mass spectrometrically (mainly by TIMS or nowadays by ICP-MS) and the primordial strontium ratio ( Sr/ Sr)o at t = 0 and the age t of the rock can be derived from the isochrone (graph of measured Sr/ Sr isotope ratios (represented on the ordinate) as a function of the Rb/ Sr ratio (on the abscissa) in several minerals with different primordial Rb concentrations). The age of the minerals will be determined from the slope of the isochrone (e — 1), and the primordial isotope ratio ( Sr/ Sr)o from the point of intersection with the ordinate (see Figure 8.9). Rb-Sr age dating is today an... 

The number of publications involved with the recovery of rubidium from seawater is very limited. Most of the work in this field is by Russian scientists, who have proposed several schemes for the combined recovery of rubidium, strontium, and potassium with natural zeolites [15, 19, 250-253, 257]. A number of inorganic sorbents with high selectivity toward rubidium were also synthesized for the recovery of rubidium from natural hydromineral sources, including seawater. Ferrocyanides of the transition-metal ions were shown to exhibit the best properties for this purpose [258, 259]. Mordenite (another natural zeolite) has recently been proposed for selective recovery of rubidium from natural hydromineral sources as well [260]. A review of the properties of inorganic sorbents applicable for the recovery of rubidium from hydromineral sources has been published [261]. Studies of rubidium recovery fix>m seawater [15, 19, 250-253] have shown that the final processing of rubidium concentrates, especially the selective separation of Rb -K mixtures remains the major problem. A report was recently published showing that this problem can be successfully solved by countercurrent ion exchange on phenolic resins [262]. 

The first single-mineral dissolution experiments to utilize radiogenic isotopes investigated the dissolution of the feldspars bytownite, microcline, and albite in flow-through cells at a pH 3 and at 25 °C (Brantley et al., 1998). Solutions from major element experiments (Stillings and Brantley, 1995) were reanalyzed for strontium and rubidium concentrations and Sr/ Sr ratios with the goal of... 

Rubidium has been determined in pine needles (SRM 1575) to demonstrate the resistance to interferences of the immersed electrode with CW laser excitation38). The concentration of matrix components such as calcium and potassium were on the order of 40 pg/ml. The measured rubidium concentration of 11.1 pg/g agreed well with the certified value. 

The rubidium content of water is subjected to the same rules as rubidium transfer from rocks to the soil and from soils into plants. On average, water from granite, gneiss and phyllite contains 14-18 pgL while that from Pleistocene and Holocene formations (diluvial sands) and Muschelkalk proved to be particularly poor in rubidium (3.1-3.5 pgL Y The rubidium contents in different soils and waters are mainly determined by the rubidium concentrations in the source material for soil formation. Anthropogenic influences on the rubidium content in the soil and water are hardly probable (Anke and Angelow 1995). 

The rubidium contents of drinking water in Germany were investigated systematically, and a mean rubidium concentration of 11 pgL and a median of 8.1 pgL were established (Anke et al. 1997b). The water of Lake Balaton in Hungary accumulated much higher rubidium concentrations (94 to 1100 pgL ) (Kovacs etal. 1985). 

The rubidium content of the flora is species-specific, and is seen to vary with the age of the plants, the rubidium concentration of the soils, and their pH value. An acid pH value of the soil supports rubidium uptake (Tyler 1983, 1997, Tyler and Zohlen 1998). 

The rubidium concentrations in the liver and kidneys of herbivorous ruminants, beasts of prey and omnivores are shown in Table 1.4-3. Depending on their rubidium offer, the livers and kidneys contained between 94 and 14 mg Rbkg DM and between 96 and 21 mg Rbkg DM, respectively. 

Predatory carnivorous shrew species from the same location as the herbivorous mice species accumulated less rubidium in their bodies. Although rubidium transfer from one trophological level to the other takes place, it leads to a reduced rubidium proportion at the higher level. This statement is supported by the rubidium content in the livers and kidneys of carnivores (cat). On an average, cats accumulated only 16-17 mg Rbkg DM, and thus remained below the rubidium concentrations found in red deer, cattle, and sheep (Angelow 1994, Kosla et al. 2001a). 

In general, the rubidium concentration decreases with increasing age in both animals and humans (Saito et al. 1993a,b). 

Absorption, Transportation, and Distribution Rubidium is very well absorbed from the alimentary tract of animals (Schafer and Forth 1983), with absorption in humans exceeding 60% in both sexes (Table 1.4-5). Rubidium resembles potassium in its pattern of absorption (channels). On the basis of studies with brush border membrane vesicles isolated from the jejuna of rabbits, potassium and rubidium apparently share a transport system. All plant and animal cells are apparently permeable to rubidium ions at rates comparable with those of potassium (Nielsen 1986). It seems that rubidium uses the potassium channels for entering the cell (Clay and Shlesinger 1983, Gallacher et al. 1984). All soft tissues of the body have rubidium concentrations that are high compared with trace elements, with a typical... 

The alkali-rich lavas analyzed by Stuckless and Ericksen (1976) have high strontium concentrations that range from 640 to 2,000 ppm, whereas their rubidium concentrations range from only 30 to 173 ppm and the average Rb/Sr ratio of the alkali-rich lavas is 0.096. The only exception is a sample of trachyte which has a high Sr/ Sr ratio of 0.70501, Sr = 48 ppm, Rb = 104 ppm and Rb/Sr = 2.17. 

The concentrations of strontium in these minerals range widely from 45 ppm in diopside to 2,400 ppm in the anorthoclase. The rubidium concentrations are... 

The most common method of analytical determination of rubidium is atomic absorption spectroscopy (AAS) or neutron activation analysis (NAA). Chemical methods of analysis for the determination of rubidium are difficult because of the tedious procedures required to effect the separation from the other alkali metals. The beneficial effects of the addition of other alkali metals, particularly potassium, sodium, and cesium, added to interfere with the ionization of rubidium is detailed by many authors [39,53-55]. Recent evaluation of the benefits of these ions in the determination of rubidium in human erythrocytes has concluded that erythrocytes should be diluted 1 50 with potassium to give a final potassium concentration of 10000 ppm. Under these conditions, the sensitivity of absorbance was increased about threefold and rubidium concentrations could be determined in the range 0-60 ppm [56]. 

The characteristic mass at the main absorption line, using a transversely heated graphite tube atomizer, is mo = l-6pg. The sensitivity obtained with HR-CS AAS, both in a flame and in the graphite furnace, is significantly better than that with LS AAS. A few less sensitive analytical lines that might be used for the determination of higher rubidium concentrations are compiled in Table 6.22 together with information about their spectral environment. 

Oernemark, U.,Taylor, P. D. P, and De Bievre, P. (1997). Certification of the rubidium concentration in water materials for the international measurement evaluation programme (IMEP) using isotope dilution inductively coupled plasma mass spectrometry.J.Anal. At. Spectrom. 12(5), 567. 

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