Shelf life reagents

The great reactivity of the sulfurane prepared by this procedure toward active hydrogen compounds, coupled with an indefinite shelf life in the absence of moisture, makes this compound a useful reagent for dehydrations,amide cleavage reactions, epoxide formation, sulfilimine syntheses, and certain oxidations and coupling reactions. 

Xenon difluoride [4, 5, 7, 8,10] is a white crystalline material obtained through the combination of fluorine and xenon m the presence of light The reagent is commercially available and possesses a relatively long shelf-life when stored cold (freezer) Xenon difluoride is very effective for small-scale fluormation of alkenes and activated nucleophilic substrates. The reactions are usually conducted between 0 °C and room temperature in chloroform or methylene chloride solutions Hydrogen fluoride catalysis is sometimes helpful Xenon difluoride reacts in a manner that usually involves some complexation between the substrate and reagent followed by the formation of radical and radical cation intermediates... 

Reilly, M. J., and Jenkins, FI. C. (1997). Factors affecting the shelf life of freeze-dried firefly luciferase reagents. In Piastings, J. W., et al. (eds.), Biolumin. Chemilumin., Proc. Int. Symp., 9th, 1996, pp. 257-260. Wiley, Chichester, UK. 

The reagent has an indefinite shelf-life in a sealed container but hydrolysis... 

All reagents are traceable to certificates of analysis, are used within the posted shelf-life, and are from known suppliers. 

A number of staining procedures have been described. Some stains, such as chlorazol black, require fresh specimens and are not widely used. A variety of stains for fecal smears preserved by Schaudinn or PVA fixative have been described, including various hematoxylin stains. The stain most widely used in the United States is the Wheatley trichrome stain, which is the only permanent stain described in this chapter. The trichrome staining procedure uses reagents with a relatively long shelf life and is easy to perform. Note that there are differences in staining times depending on whether the specimen is fixed in Schaudinn or PVA fixative, as penetration is slower in the latter. 

Analysis Bottle material Bottle size Reagents in bottle Shelf life Notes... 

In conclusion, NPOEs, which can be prepared and manipulated routinely, have excellent shelf life, but can yet be readily activated by the action of mild reagents. 

Reagents, standards, and controls nsed in the assay and instructions on their preparation, storage, and shelf life. 

Improper storage of reagents or expired reagents Some antibodies can be aliquoted and frozen to extend their shelf life. 

Reagents should have reasonable shelf life with no availability problems. Quality control of reagent lots must be available if questions of sensitivity or specificity should arise. 

Lipshutz2 notes that the shelf-life of the reagent suggests that a simple in-situ preparation serves well ... 

Perform analysis in duplicate (repeat titration). Store at room temperature in a glass reagent bottle sealed with a rubber stopper. The standardized NaOH may be stored up to two months. A white swirling precipitate often appears in the standardized NaOH at the end of its shelf life, at this point the normality is still stable but this can be used as a visual sign of the end of the shelf life. 

The ELISA techniques offer advantages of longer shelf life of the labelled reagents and elimination of the use of radioisotopes which require expensive scintillation/gamma counters and special disposal needs (38, 56). They are also more sensitive than the RIA s. ranging from pg/ml to pg/ml depending on the size of the molecules, affinity of the antibody and the assay format used (48). 

Test procedures are written procedures that provide the step-by-step details of how to perform the tests indicated in specifications or SOPs. They indicate the reagents to be used, sources of the chemicals, how the reagents are to be prepared, and the shelf life of the reagents. Also described are the apparatus to be used and special handling and precautions to be followed. At times a compendial test procedure is not in sufficient detail for a laboratory technician to follow exactly. In such a case, the procedure should be written in the necessary detail. A laboratory technician should not run a test without having the proper written procedure. 

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