Chemical reagents suppliers

Catalogues of Chemical Reagent Suppliers, (Aldrich, Sigma, Wako, Kanto). 

We advance several reasons for discussing the deceptively simple synthesis of ILBSs and their parent ILs a search in the catalog of a major chemical reagents supplier has shown that only a very few ILBSs are commercialized. If the purities in these surfactants are similar to those of the structurally related ILs, commercialized by the same supplier, then this purity is not satisfactory, because 81% have purity less than or equal to 98% (Fig. 4.2). Note that surface-active purity ... 

The history and chemistry of the hydroxy-oxime extractants which were originally developed for Cu recovery has been extensively reviewed.11,13,14 Szymanowski s book14 provides comprehensive cover of the literature prior to 1993 and assigns chemical structures to reagents which in most metallurgy texts are referred to only by codes provided by reagent suppliers. An updated version of this information is provided in Table 3. 

There exist a multitude of chemical reagent sources. The Available Chemical Directory (ACD) collection, from Symyx Technologies Inc., lists as many as 1,160,000 unique chemicals with chemical structure, pricing, supplier, purity, forms, etc. 

In contrast to most chemical reagents, which are usually of the same quality regardless of the supplier, the source of solid support is extremely important. Thus, distinct solid supports from different manufacturers or even from the same one, but from separate batches, may differ in performance. Consequently, the choice of the solid support source can have a significant influence on the result of the chemical process. If the large-scale synthesis of a molecule or the production of a library is preceded by an optimization step, both steps should be carried out with the same batch of solid support. 

The American Chemical Society publishes a compendium of tests for evaluating the purity and quality of basic laboratory chemicals. Reagent chemicals that do not reference the ACS meet the manufacturer s own reagent specifications, which vary among suppliers. 

Chemicals labels, specification sheets, and literature provided by the supplier can be referenced for shelf life of chemicals. Reagent bottles should be marked when received and when opened. 

All raw materials are subject to the QA/QC system prior to acceptance. Raw materials are controlled for their compliance with procurement specifications. A conformity file is systematically established that documents the quality of glass frit and chemical reagents, the glass canister procurement, the smear test swab, and welding torches. In addition, Cogema is performing audits and inspections of the raw materials suppliers. 

It is also important that the chemist should make an educated selection of the other major tools of his profession, including chemical reagents. In many cases, advice is readily available from suppliers, especially with regard to the choice of materials for well-established analytical methods. However, the rate of change in analytical chemistry is fast, and when a new technique is employed there may not be chemicals readily at hand that are suited to the purpose, and they may not become available for many years until the demand is of sufficient commercial interest. In the meantime, the analyst is faced with the prospect of purifying materials. This is the subject of the second article in this entry on analytical reagents. 

DFP is commercially available through suppliers of laboratory chemical reagents. 

Protected nucleosides and nucleoside-3 -succinates are commercially available from a variety of biochemical reagent suppliers (i.e., Sigma Chemical Co., St. Louis, MO, or Penninsula Laboratories, Inc., Belmont, CA), or they may be prepared by following published procedures (2). 

This reagent is obtainable from major chemical suppliers. 

For all procedures, the submitters employed reagents (Aidrich Chemical Company, Inc., or Spectrum Chemical Mgf. Corp.) and solvents as supplied from commercial suppliers without purification. 

This reagent was obtained either from Aldrich Chemical Company, Inc., or Lithium Corporation of America, Bessemer City, NC. A technical data sheet is available from the suppliers. Solutions of ca. 2 M were titrimetrically analyzed for active alkyllithium by the tosylhydrazone method. It is advisable to make certain that the organolithium reagent to be used was prepared in pentane solution. This evaluation can be easily accomplished by the gas chromatographic analysis of the organic layer obtained from the hydrolysis, under a nitrogen atmosphere, of the tert-butyllithium solution to be used. Isobutane and pentane should comprise essentially all of the... 

MSDS (Materials Safety Data Sheets) sheets are available from the suppliers of commercially available reagents, solvents, and other chemical materials anyone performing an experiment should check these data sheets before initiating an experiment to learn of any specific hazards associated with the chemicals being used in that experiment. 

Depending on the supplier and batch of amido black, the sensitivity of protein detection with this reagent may vary If the sensitivity of staining is not satisfactory, it is advisable to dilute the amido black solution 5-10 times with water rather than to increase its concentration. In our hands, amido black purchased from Research Organics (Cleveland, OH) or Sigma Chemical Co. (St Louis, MO) gives optimum results. 

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