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Thin-layer chromatography impurities/degradants

Many impurities are present in commercial caprolactam which pass into the liquid wastes from PCA manufacture from which caprolactam monomer may be recovered. Also, the products of die thermal degradation of PCA, dyes, lubricants, and other PCA fillers may be contained in the regenerated CL. Identification of die contaminants by IR spectroscopy has led to the detection of lower carboxylic acids, secondary amines, ketones, and esters. Aldehydes and hydroperoxides have been identified by polarography and thin-layer chromatography. [Pg.540]

Ordinary impurities are considered innocuous in that they have no significant undesirable biological activity at or below the specified limits. These impurities arise from the synthesis, formulation, or degradation of the drug. The USP monograph for glycopyrrolate contains a thin-layer chromatography (TLC) test for ordinary impurities for which the limits are 0.5% for individual impurities and 2.0% for the total of all impurities. [Pg.3625]

A radiopharmaceutical has adequate radiochemical purity when the fraction in the form of the wanted chemical form is high enough to meet specifications. Radiolysis (degradation due to own radiation) and the usual factors that affect stability (light, oxidation, reduction, pH shifts), may cause incomplete or slow labelling, degradation and create radiochemical impurities. Thin layer chromatography is the most widely used technique for the analysis of radiochemical purity. HPLC techniques may also be used, for instance for the assessment of the radiochemical purity of PET radiopharmaceuticals. [Pg.320]

TLC is a good technique to use when normal-phase solvents provide optimum separation. Typical thin-layer separations are performed on glass plates that are coated with a thin layer of stationary phase. The stationary phases used in TLC encompass all modes of chromatography including adsorption, normal- and reverse-phase, ion-exchange, and size-exclusion." The equipment required is simple and inexpensive. TLC is an ideal technique for the isolation of compounds because of its simplicity. However, for TLC to be successful, the impurity and/or degradant level should be at or above 1%. Any component present below this level is very difficult to isolate on a TLC plate because of higher detection limits. [Pg.122]


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