Impurities salt-related

Often the impurities observed from TLC analysis are unknown. In this case, identification of the impurities may become necessary, depending on the level of impurities (ICH Impurity Guideline). Questions one should first ask are, Is the impurity real or an artifact Is it salt-related If the answers are No to these two questions, isolation and characterization are required to identify the impurity. 

In some situations, the salt, when bound to the drug substance, can have a different Rf value than when the salt is applied to the plate itself. In the example shown in Figure 17, a spike experiment is conducted to show that the salt s Rf value changes when in the presence of the drug substance. Therefore, the impurity band is identified as salt related. 

Nuclear wastes are classified according to the level of radioactivity. Low level wastes (LLW) from reactors arise primarily from the cooling water, either because of leakage from fuel or activation of impurities by neutron absorption. Most LLW will be disposed of in near-surface faciHties at various locations around the United States. Mixed wastes are those having both a ha2ardous and a radioactive component. Transuranic (TRU) waste containing plutonium comes from chemical processes related to nuclear weapons production. These are to be placed in underground salt deposits in New Mexico (see... 

Photocopies of journal articles relating to the Unipet process for the recycling of PETP developed by United Resource Recovery Corp. Details are given of the process which enables contaminated PETP to be recycled by the use of caustic soda which reacts with the PETP to yield ethylene glycol and terephthalic acid, followed by heating and evaporation of the EG which reduces organic impurities to carbon dioxide and water and leaves solid terephthalic salt. Its implications for the industry are also discussed. 

Although it has been long known that trimethylene dithiotosylate can be prepared by the reaction of thiotosylate ion with trimethylene dibromide,3 5 various difficulties are associated with the preparation. These problems are to a considerable extent related to the mode of preparation and the resultant purity of potassium thiotosylate. The thiotosylate salt must be free of tosylate and p-toluenesulfiriate impurities, otherwise side products such as tosylates or sulfones will form. One such by-product, tosyltrimethylene thiotosylate,... 

The ionic conductivity at the end of a polymerisation is due to whatever cations Pn+ are formed or left when the monomer is exhausted and the anions A- of the initiating salt, plus a very minor contribution from the ions formed from impurities, which will be ignored. In order to analyse the relation between the observed iq, c0 and the ionic conductivity A of the electrolyte, it is necessary to clarify the electrochemistry of the solutions. We note first that the polymeric cations, whatever their structure, (i.e., as they were when propagating or subsequently isomerised), are much larger than the anions, SbF6, so that these carry virtually all the current so that A A, (SbF6), and therefore A, can be calculated-see below. Next, we note that all the iq- c0 plots, including that reported earlier [2], are rectilinear. This means ... 

Related compound (B) has the systematic name methyl-( )-(o-chloro-phenyl)-4,5-dihydrothieno[2,3-c]pyridine-6-(7H)-acetate, hydrogen sulfate salt [2], and is a racemic residue formed during the manufacturing process. This compound may appear as a racemic mixture in samples of bulk drug substance as impurities (la) and (lb) [6, 7]. 

Chemical treatment of natural waters. Both directly and indirectly, the general problem of purification and treatment of natural waters is related to the chemical and physical properties of the normal and acid salts of carbonic acid. The common impurities in natural waters consist of suspended solid organic and inorganic materials and of certain dissolved salts, particularly the acid carbonates, chlorides, and sulfates of sodium, calcium, and magnesium. The solid matter may be removed by filtration, the presence of limited quantities of sodium salts is not objectionable, and the calcium and magnesium salts are eliminated only through appropriate chemical treatment. The ions that are most... 

There is no current commercial biologic process for the production of succinic acid. In past laboratory systems, when succinic acid has been produced by fermentation, lime is added to the fermentation medium to neutralize the acid, yielding calcium succinate (2). The calcium succinate salt then precipitates out of the solution. Subsequently, sulfuric acid is added to the salt to produce the free soluble succinic acid and solid calcium sulfate (gypsum). The acid is then purified with several washings over a sorbent to remove impurities. The disposal of the solid waste is both a directly economic and an environmental concern, as is the cost of the raw materials. Some key process-related problems have been identified as follows (1) the separation of dilute product streams and the related costs of recovery, (2) the elimination of the salt waste from the current purification process, and (3) the reduction of inhibition to the product succinic acid on the fermentation itself. Acetic acid is also a byproduct of the fermentation of glucose by Anaerobiospirillium succiniciproducens almost 1 mol of acetate will be produced for every 2 mol of succinate (3). Under certain cultivation conditions by a mutant Escherichia coli, lesser amounts of acetate can be produced (4,5). This byproduct will also need to be separated. 

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