Precipitates, acid treatment

H2O, protamine precipitation, (NH4)2S04 fractionation, Me2CO precipitation, acid treatment at pH 5.7 and precipitation at pH 4.5. The equilibrium constant for pyruvate + -acefyl-D-mannosamine A-... 

Silver Chloride. Silver chloride, AgCl, is a white precipitate that forms when chloride ion is added to a silver nitrate solution. The order of solubility of the three silver halides is Cl" > Br" > I. Because of the formation of complexes, silver chloride is soluble in solutions containing excess chloride and in solutions of cyanide, thiosulfate, and ammonia. Silver chloride is insoluble in nitric and dilute sulfuric acid. Treatment with concentrated sulfuric acid gives silver sulfate. 

Prior to Treatment After Treatment by THF-Benzene Precipitations After Treatment by 56-hr Acid Boil ... 

Contamination from other L-iduronic acid-containing glycosaminoglycans (dermatan sulfate and heparan sulfate species) cannot usually be lowered below the 1-2% level, unless repeated precipitations or treatments with resin are made. As will be discussed in Section VIII, extensive... 

Acute intermittent porphyria is a dominantly inherited partial deficiency of porphobilinogen deaminase, and causes axonal polyneuropathy. Acute intermittent porphyria is caused by partial deficiency of porphobilinogen deaminase, an enzyme required for heme biosynthesis. Patients may present with acute abdominal pain, rapidly progressive sensorimotor axonal polyneuropathy or psychosis, and have elevated concentrations of the heme precursor 8-amino-levulinic acid in their urine. Symptoms may be precipitated by treatment with barbiturates or other drugs and are suppressed by treatment with hematin [59]. 

To increase the solubility of calcium carbonate and reduce its potential for precipitation and hence membrane fouling, the pH of the feed water is lowered through the addition of acid (Greenlee et al. 2009). Sulphuric acid and hydrochloric acid are most commonly used. Acid treatment can also help to improve the coagulation of colloids and slightly increase the solubility of silica (Bergman 2007). 

GaUium may be recovered from zinc sulfide ores by a series of steps that include oxidation, acid treatments, neutralization, precipitation, alkali treatment, and electrolysis (Foster, L.M. 1968. Gallium. In the Encyclopedia of Chemical Elements, ed. C. L. Hampel, pp. 231-237, New York Reinhold Pubhshing Corp.). The process is described below. 

The preferred preparation method is to introduce chlorine into the solution while dissolving lead dioxide in cold concentrated HCl. This prevents decomposition of PbCL to PbCb and enhances the formation of chloroplumbic acid, H2PbCl6 in solution. Addition of ammonium chloride precipitates out yellow ammonium chloroplumbate, (NH4)2PbCl6, which is filtered out. The yellow precipitate, on treatment with cold concentrated sulfuric acid, forms lead tetrachloride, which separates out as a yellow oily liquid. The reactions are ... 

In another industrial process, flue dusts from smelting lead and zinc concentrates are boiled in acidified water. Thallium dissolves and is separated from insoluble residues by filtration. Dissolved thallium in solution then is precipitated with zinc. Thallium is extracted from the precipitate by treatment with dilute sulfuric acid which dissolves the metal. The solution may also contain zinc, cadmium, lead, copper, indium, and other impurities in trace amounts. These metals are precipitated with hydrogen sulfide. The pure thallium sulfate solution then is electrolyzed to yield thallium. 

Extraction is commonly carried out by hydrolysis in boiling acid such as chloridric acid or sulfuric acid. To release thiamine bonded to phosphate enzyme, hydrolysis with phosphatase, alone or together with claradiastase or takadiastase, is carried out. After the enzymatic digestion, an acid treatment is applied in order to precipitate the protein and denaturate the enzymes. Ndaw et al. [603] proved that for extraction of vitamins Bj, B, and Bg, acid hydrolysis is always superfluous if the activity of the enzymes chosen is sufficiently high. SPE or column chromatography may be used in further purification, mainly to remove excess of derivatization reagents used to convert thiamine to a highly flnorescent thiochrome derivatives. lEC may be used in purification step, as well. 

Lithium.—Lithium oxide was discovered by A. Arfvedson, in 1817,10 while analyzing the mineral petalite. His report was entitled Untersuehungen einiger hei der Eisen-Grube von Ulo vorkommenden Fossilien und von einem darin gefundenen neuen feuerfesten Alkali. He found the sodium to be contaminated by an alkali which, unlike potassium, was not removed as a precipitate by treatment with tartaric acid, and, unlike sodium, it formed a sparingly soluble carbonate. The... 

If iron is present, the dry residue is subjected for several weeks to sunlight which renders the iron insoluble in acetic acid, after which acetic acid dissolves the calcium and magnesium carbonates which are separated by dilute sulphuric acid, precipitating calcium and dissolving magnesia. The residue from acetic acid treatment consists of clay, silicious matter and iron. The clay and iron are dissolved by marine acid (hydrochloric) and the iron precipitated by caustic alkali (phlogisticated alkali) and the clay by alkali carbonate. The silicious matter may be identified by its complete solution with effervescence under the blowpipe with mineral alkali (sodium carbonate). 

The silver acetylides appear to have substantially covalent carbon-metal bonds and are less ionic than sodium and potassium alkynides. Silver-ammonia solution may be used to precipitate 1-alkynes from mixtures with other hydrocarbons. The 1-alkynes are regenerated easily from the silver precipitates by treatment with strong inorganic acids. It should be noted, however, that silver alkynides may be shock sensitive and can decompose explosively, especially when dry. 

This substance forms salts with acids, and was first isolated in the form of its nitrate. The nitrate is not detonated by shock but undergoes a rapid decomposition with the production of light when it is heated. The picrate and the perchlorate explode violently from heat and from shock. Guanyl azide is not decomposed by boiling water. On hydrolysis with strong alkali, it yields the alkali metal salt of hydrazoic acid. It is hydrolyzed by am-moniacal silver nitrate in the cold with the formation of silver azide which remains in solution and of silver cyanamide which appears as a yellow precipitate. By treatment with acids or weak bases it is converted into 5-aminotetrazole. 

Prolonged administration of nicotinic acid can have a diabetogenic effect and decompensation of previously stable diabetes can occur. Severe hyperglycemia has been precipitated by nicotinic acid treatment of hyperlipidemia (24). 

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