Water rubidium content

The accuracy of the activation analysis method when applied to sea water has been checked by comparison with other methods in the case of rubidium and strontium. The rubidium content (Table VI) of a sample of... 

Chaudhuri, S. Clauer, N. (1993) Strontium isotopic compositions and potassium and rubidium contents of formation waters in sedimentary basins clues to the origin of the solutes. Geochim. Cosmochim. Acta, 57, 429-437. 

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 water-solubility of rubidium is reduced to 80% with increasing rubidium content of the tea, such that only 46% of the rubidium contained in fruit tea mixtures is transferred into the beverage. On the average of many tea blends, an 85% rubidium transfer into the beverage can be expected. 

Due to the high water-solubility of rubidium, the high content in beverages and fruit juices is not surprising. The rubidium content in beverages is subjected to most considerable variations (Anke and Angelow 1994). 

Despite apparently similar foodstuffs being available at all supermarkets, the location affected rubidium intake because of the different rubidium contents of drinking water. Notably, those people who drank rubidium-rich drinking water from rubidium-rich gneiss regions took in significantly more rubidium than those in other areas. 

Rubidium.—Bb, a.n. 37 a.w. 85 45. Sheldon and Bam e (1931) find rubidium as a constant micro-constituent in aU human tissues, but its occurrence in lower animals and plants is very sporadic. The metal is closely related to potassium, and Bubenstein reports that marine diatoms and possibly some of the seed plants can replace Bb+ for K+ in cell growth. Higher animals cannot survive such substitutions. The rubidium content of sea water is assessed by Schmidt at 10-15 mg. per litre, a value that is almost certainly excessive in view of the fact that Ramage finds that marine animals never contain more Bb than 0 002 per cent, of their dry weight. 

A reference solution is used to compensate for the influence of the potassium. It consists of a precipitate of a quantity of potassium, prepared in the same way, corresponding to the content of potassium ions in the quantity of water used for the rubidium and caesium determination. This generally entails no particular difficulty since a determination of potassium precedes the determination of Rb and Cs in the course of w.ater analysis. Experience shows that the potassium content in water hardly ever exceeds 300 mg/1. Consequently, the method has been adapted to a constant potassium content of 200 mg/1, which may be achieved by adding potassium chloride if the content of the natural water sample is lower. 

Interferences occur if the acetone used for the solution contains more than 1 % water. A water content greater than 1 % has the effect of overvaluing rubidium readings and undervaluing caesium readings. 

Depending on the rubidium and caesium content to be expected, up to 1 litre of the water sample acidified with hydrochloric acid is concentrated to approximately 200 ml by evaporation. After cooling, the total concentration of potassium in the samples is raised to some 50 mg by means of the potassium solution. The sample to be analyzed is subsequently heated to 0 - 50 C, 20 ml of a 4.5 % sodium tetraphenylborate solution added and stirred, and rubidium and caesium precipitated jointly with potassium. 

We are strictly content with studying quantitative determinations with tetraphenyl-boron ion (TPB) ( 6115)46 . Its sodium and lithium salts are soluble in water. Its rubidium, cesium, potassium, and ammonium salts are very poorly soluble. The solubility product of potassium tetraphenylboron is Als(K(C6H5)4B) = 2.25 x 10 . Likewise, numerous quaternary ammoniums and protonated amines form slightly soluble salts with tetraphenylboron ion according to the reaction... 

The Michigan Basin brines very low pH helps to explain their ability to leach and react with other rocks, as is indicated by their high contents of strontium, barium and other metals, although much of the Sr and Ba probably came from the reaction with calcite. Geothermal water also probably mixed with some of the formations, as indicated by the variable presence of iodine, boron, lithium, cesium, rubidium and other rare metals. With most of the brines, the calcium concentration is somewhat higher than its magnesium equivalent in seawater end liquor from a potash deposit, and the potassium a little lower. Wilson and Long (1993) speculated that this occurred by the conversion of the clays kaolinite and smectite to illite ... 

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