Metabisulphite

Evaporation and crystallisation of the sodium sulphite solution gives crystals of the heptahydrate NajSOj.THjO. However, on evaporation of the hydrogensulphite solution, the solid obtained is chiefly sodium pentaoxodisulphate(IV) ( metabisulphite ) Na2S20j, and contains little if any of the hydrogensulphite. However, the hydrogen sulphite ion is obtained when the solid redissolves in water ... 

Bisulphite. My personal nightmare. I use metabisulphite, what I think it s the same. Sometimes product is unfilterable, other one couldn t be recovered with NaOH solution. Investigate, I m not a great chemist. Solvent, /Va/VO or PcfC/j may be can be reduced, but I think the quantities in this sample are really good. Solvent is easily evaporated, NaN02 could be only slightly reduced and Pddi is about 4,5 % versus 6 % in patent, but it s enough because all safrol reacts. Well, I think it s all... ... 

Transfer of an active chemical agent in an inherently safer form (e.g. sulphur dioxide as sodium metabisulphite, chlorine as sodium hypochlorite). Generation of an active agent in this manner clearly reduces the inventory in use. 

Sodium disulphite solution (sodium metabisulphite). Dissolve 0.5 g of the solid reagent (Na2S205) in 10 mL water. Prepare fresh daily. 

Sulphur dioxide has extensive use as a preservative in the food and beverage industries. In a pharmaceutical context, sodium sulphite and metabisulphite or bisulphite have a dual role acting as preservatives and antioxidants. 

Chemical stability. Some medicaments undergo chemical change in aqueous soluhons. If the change is due to oxidation, a reducing agent such as sodium metabisulphite is included (e.g. Adrenaline Injection BP). 

Wedzicha, B.L., Chemistry of Sulphur Dioxide in Foods, Elsevier, Amsterdam, 1984. Damant, A., Reynolds, S., and Macrae, R., The structural identification of a secondary dye produced from the reaction between sunset yellow and sodium metabisulphite, FoodAddit. Contam., 6, 273, 1989. 

Pulp from ripe Golden apple was pressed in a mortar and filtered, thus obtaining a cloudy and dense juice. Potassium metabisulphite was added as antioxidant at a final concentration of 0.15 mg/mL. The pH of the prepared apple juices was 4.1 4.3. Depectinisation experiments were carried out loading the juice in the packed bed reactor and recycling for 30 min at 25 "C. The reaction mixture was then collected and the percentage reduction of viscosity measured as above described. The y-alumina spheres were abundantly washed with distilled water before performing the successive batch reaction. 

Potassium pemnanganate Potassium nitrite Potassium nitrate Potassium sulphite Potassium stannate IV Potassium sulphate Poptassium metabisulphite Potassium peroxodisulphate Potassium tellurate (IV) Potassium pyrophosphate... 

Japanese workers have described a stable aqueous solution of neomycin with the incorporation of a borate buffer (pH 6) and E.D.T.A.295 The presence of 1-10% of glycerol, propylene glycol or mannitol has been claimed to improve the solution appearance by preventing discoloration29°. The presence of polyols also prevented a decrease in pH value of the solution. Discoloration may also be prevented by addition of 0.1% sodium metabisulphite at a solution pH of 6.6 to 6.8297. 

Finally, in a method originated by Witt [22], which is occasionally useful for the diazotisation of stable amines of high relative molecular mass that pose solubility problems, the amine is dissolved in nitric acid before the addition of sodium metabisulphite. Nitrous acid is produced in the medium according to Scheme 4-9, enabling diazotisation to proceed. 

Methylaminophenol-sulphite Solution Dissolve 0.1 g of 4-methylaminophenol sulphate, 20 g sodium metabisulphite and 0.5 g anhydrous sodium sulphite in sufficient DW to produce 100 ml. 

Theory Sodium metabisulphite in acidic medium (HC1) yields S02 which reacts with water to produce sulphurous acid. The generated sulphurous acid is quantitatively oxidized by iodine to sulphuric acid, and the excess iodine is subsequently back titrated with sodium thiosulphate. The various reactions can be expressed as shown below ... 

Materials Required Sodium metabisulphite 0.2 g 0.1 N Iodine solution hydrochloric acid ( 11.5 N) 1 ml 0.1 N sodium thiosulphate starch solution. 

Procedure Weigh accurately about 0.2 g of sodium metabisulphite and dissolve in 50.0 ml of 0.1 N iodine solution and add 1 ml hydrochloric acid. Titrate the excess of iodine with 0.1 N sodium thiosulphate employing freshly prepared starch solution, added towards the end of the titration, as indicator. Each ml of 0.1 N iodine is equivalent to 0.0047453 g of Na Oj. 

The trichlorides obtained by the alkoxytellurination of alkenes (see Section 3.5.1.2) or by the cyclotellnrination of hydroxyaUcenes (see Section 4.6.2.4) are reduced in situ, without isolation, with sodium metabisulphite. ... 

Pal BB, Bhunya SP Genotoxic effect of a preservative, sodium metabisulphite as revealed... 

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