Degradation products and impurities

Other substances may be present in food contact plastics that were not originally intended to be present in the finished material or article, but arise from reactions during polymerisation or processing. Or they may be present as 

6-naphthalene dicarhoxylic acid, dimethyl ester 22390 Monomer 0.05 mg/kg 

Adipic acid, his(2-ethyUiexyl)ester 31920 Carrier for colourants 18 mg/kg 

Another class of secondary antioxidants used in food contact plastics is thioether. The most common examples used in polypropylene, polystyrene and PVC are thiodipropanoic acid, didodecyl ester (DLTDP) and thiodipropanoic acid, dioctadecyl ester (DSTDP). Thioethers react with hydroperoxides to form sulphoxides as shown in Fig. 10.8. 

Use of both primary and secondary antioxidants usually provides a synergistic effect, where the combined effect of two or more stabilisers is greater than the sum of the effects of the individual stabilisers. It is common practice to include both a phosphite, such as tris(t-butylphenyl)phosphite and a hindered phenol, such as octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyljpropionate to provide improved heat stabilisation in polyolefin formulations. 

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Persson Stubberud, K., and Astrom, O. (1998). Separation of ibuprofen, codeine phosphate, their degradation products and impurities by capillary electrophoresis II. Validation. /. Chromatogr. A 826(1), 95-102. 

In reference 68, a different approach was used to verify the robustness of a CE separation of ibuprofen, codeine phosphate, degradation products, and impurities in a drug product (tablet). Small variations around the optimal conditions obtained during method optimization were introduced and the results were predicted from the response model. The variations in the factor levels during the robustness evaluation were smaller than those evaluated during method optimization. Since both migration times and resolutions were acceptably predicted, the method was considered robust with respect to the small changes. The examined factors... 

An MEKC method for the determination of ibuprofen, codeine phosphate hemihydrate, their nine potential degradation products, and impurities in a commercial tablet formulation was developed, optimized, and fully validated according to ICH guidelines and submitted to the regulatory authorities. The optimized system containing ACN as organic modifier allowed baseline separation of ibuprofen, codeine, and nine related substances within 12 min. 

LC/MS ANALYSIS OF NERVE AGENTS, THEIR DEGRADATION PRODUCTS, AND IMPURITIES... 

Two additional properties of filters, which are less apparent but still important in filter performance, are the extractables and affinity for the analyte. These filter properties are not as easy to predict for drug degradation products and impurities in that these compounds are often of unknown structure and poorly characterized. With regards to analyte affinity, it is useful to conduct a recovery study to ascertain the extent to which an analyte adheres to the membrane. This is not always practical if the prefiltrate is not suitable for direct chemical analysis or if the sample is precious. 

The aim in paper I was to develop a method capable of separating the product and the substrate from each other and from degradation products and impurities from the fermentation medium to enable rapid product identification. The aim in paper II was to develop a method for accurate quantitative analysis of both products and substrate with high precision. It was also desired that the strategies used in paper I and guidelines given in paper II should be useful for ordinary fermentation laboratories. 

Ibuprofen, codeine phosphate, and their main degradation products and impurities Fungal metabolites... 

Once formed, lewisite oxide and polymerized lewisite oxide are relatively insoluble in water. Once dry, the oxide will probably not readily redissolve or form the acid in the environment. The degradation products (and impurities) of lewisite are listed in the Appendix, Table A2. 

Potential GA degradation products and impurities are listed in the Appendix, Table A4. Impurities may account for up to 28% of the volatile organic content of munitions-grade GA. The... 

Table Al. Degradation products and impurities of sulfur mustard agent (HD) 1 6...

Diethyl methylphosphonate 0,0 -Diethyl methylphosphonate C5H13O3P 683-08-9 Present in tonne containers, degradation product and impurity... 

The pharmaceutical analysis deals with an array of therapeutic agents either alone or in combinations that are incorporated in dosage forms of extreme characteristics. The main aim of pharmaceutical analysis is to analyse the compounds accurately and as quickly as possible. Amongst several analytical techniques that are used, HPLC is one of the most commonly used techniques for the analysis and separation of an array of therapeutic agents from their degradation products and impurities. In conventional HPLC, often... 

After CTA treatment, chromatograms of some standard substances show additional zones in UV-3fi.5mn, due to degradation products and impurities. 

Fong, G.W.K. Martin, D.T. Johnson, R.N. Kho, B.T. Determination of degradation products and impurities of amoxicillin capsules using ternary gradient elution high-performance liquid chromatography. J.Chromatogr., 1984, 298, 459-472... 

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