Preparation and Storage of Solutions

Preparation and storage of solutions water quality and the purity of chemical reagents... 

Lanina SY, Strakhova NM, Lappo VG. 1992. Toxicological estimate of polyvinyl chloride containers for preparation and storage of blood, its components, preservatives and infusion solutions. Med Prog Tech 18 19-22. 

Thiatriazole-5-thiol and its salts are readily obtained from the water-soluble alkali or alkaline earth azides with CS2 at 40 °C <64AHC(3)263>. However, these salts should be handled with extreme care as violent explosions have been reported when the alkali salts are spread on a porous plate or rubbed with a spatula. The slightly soluble heavy-metal salts are very sensitive to shock even under water. An improved method for the preparation and storage of sodium thiatriazole-5-thiolate has been reported. The free acid is obtained by addition of concentrated hydrochloric acid to a chilled solution of the sodium salt but can also be prepared from hydrazoic acid and carbon disulfide (Scheme 38). 

The terms defined above are perhaps illustrated by using the example of the simple assay which we have mentioned before. The assay in Box 1.3 is laid out in the style of a SOP. This particular section of the operating procedure describes the assay itself but there would also be other sections in the procedure dealing with safety issues, the preparation and storage of the solutions used for extraction and dilution, the glassware required and a specification of the instrumentation to be used. 

Materials. Since the oxidation of thiols is strongly catalyzed by traces of metal ions, all experimental techniques were designed to prevent the introduction of extraneous metallic impurities. Preparation and storage of reagents were completed in acid-washed, steam-cleaned glassware. Deionized water was used to prepare all solutions. 

Preparation and Storage of Titanous Chloride Solution- for Analysis.—... 

Water. A laboratory engaged in careful electrochemical work with aqueous solutions or in trace analysis will need facilities for the preparation and storage of highly purified water. Water commonly is contaminated with metals in both dissolved cationic form and in the form of colloidal or particulate matter that is not ionized appreciably.70 Frequently it also is contaminated by bacteria and by organic impurities that cannot be removed by ordinary or oxidative distillation because of the steam volatility of the impurities.71... 

So-called stock solutions are solutions typically 10, 100 or 1000 times more concentrated than that ultimately required in the final solution. Stock solutions are particularly useful when the same ingredients are required in multiple test solutions, when various concentrations of these ingredients are required or simply for storage purposes. A useful example is fruit-flavoured drink concentrates (syrups or cordials) that are mixed/diluted with water to taste if these drinks were pre-diluted they would typically fill hundreds of bottles. The same principle applies to the preparation and storage of chemical concentrates for preparation of laboratory reagents, solutions and buffers. 

Aqueous solutions of Cr are generally unstable and undergo rapid disproportionation to Cr and Cr . However Cr complexes with tertiary hydroxy acids such as 2-hydroxy-2-methylbutyric acid and citric acid are stable and permit the preparation and storage of aqueous solutions of Cr compounds. Cr complexes with deuteriated diols have been identified as intermediates in the reaction of CrO " with diols. E.s.r. studies suggest structure (8) for these complexes. With pinacol a similar... 

This approach is less useful however when one of the different chemical species involved yields a less stable solution small volumes of the single reagent should then be prepared shortly before use. On the other hand, the use of several reagents permits the preparation and storage of large volumes of more stable solutions, and only reagents yielding less stable solutions should be prepared in low volumes immediately before use. 

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