Strongly Alkaline Phosphate-Free

The contents of the flask are shaken for a considerable time with aqueous copper sulfate solution and left to stand for several hours in the well-ventilated hood. The remaining oil (which must be free of phosphorus) is transferred to the container used for halogen-free organic solvents, while the aqueous suspension is oxidised by adding a strongly alkaline 10 % NaOCl solution dropwise with cooling and then stirred with milk of lime. The precipitate, which consists of copper phosphate and hydroxide, is disposed of with the less toxic inorganic waste, and the aqueous solution neutralised and poured down the drain. 

Buffers hitherto proposed have not exceeded a pH of 10.0. Accordingly the same authors have prepared a series of mixtures for strongly alkaline media. Sodium carbonate-borax mixtures are used for the range 9.20-11.0, whereas between 11.0 and 12.2 mixtures of disodium phosphate and sodium hydroxide are employed. When buffers with a still higher pH are needed, they may be obtained conveniently by diluting 0.1 N NaOH with carbonate free water. 

Most protein molecules, then, have many points where complexes may be formed with metals. Among these metals it is worthwhile to distinguish those which appear to be coordinated strongly and by many different polar side-chains such are mercury, silver, copper and zinc. The alkaline earth metals, like calcium, seem to be bound primarily by free carboxyl groups, or, in the phosphoproteins such as casein, by phosphate groups. 

Adsorption by Clays. — Owing to the possibility of chemical reactions between the clay and the adsorbed substances, the phenomena here are much more complicated than is ordinarily the case with many colloidal systems. According to Sullivan changes between the radicals are often involved. For instance when acid or neutral salts are adsorbed, sodium, potassium, and magnesium from the clay may be released or dissolved, while an equivalent amoimt of the adsorbed basic radical remains with the clay. The addition of alkaline solution is still more complicated. Not only may there be free alkali but basic solutions may be formed because of the hydrolysis of salts of a strong base and a weak acid, e.g., carbonates and phosphates. Three different reactions are now possible. First, the free alkali may react with the colloidal silica. Second, the silicate radical from the clay may form insoluble salts with the adsorbed base. Third, the sodium, potassium, or magnesium displaced from the clay may form soluble carbonates and phosphates, and these salts in turn be adsorbed by the clay constituents. These reactions are of great importance in the study of the fertilization of the soil. It has been claimed that the addition of lime not only neutralizes the undesirable acids, but also renders the potassium of the clay available for the plant. 

The activity of alkaline phosphatase is measured by hydrolysis of />-nitrophenyl phosphate to yield -nitrophenol and free phosphate. At alkaline pH, -nitrophenol dissociates the / -nitrophenylate ion has a strong yellow colour, with maximum absorbance at 405 nm. 

Waters may be alkaline due to the presence of a wide variety of salts of weak acids such as carbonates, bicarbonates, borates, silicates, phosphates, etc., and also due to the presence of weak and strong bases (due to contamination with industrial wastes). Ibe major portion of alkalinity in natural water is, however, caused by presence of bicarbonates that are formed in appreciable amounts when water containing free CO2 percolates through soils containing CaC03 and/or MgC03 ... 

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