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Gas Chromatography Essay

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Residual solvents are defined as organic volatile impurities that may remain in active Pharmaceutical substances, excipient or medicinal products after processing. During the manufacturing processes, the solvents are not completely removed. The solvents may be used to improve the yield in the synthesis of active pharmaceutical substances besides imparting characteristics of crystal form, purity and solubility. Residual solvents do not have any therapeutic effect. Therefore, efforts should be made to remove them to the extent possible to meet the specification prescribed [2]. Gas chromatography method has been developed to find out the purity of acetone, dichloromethane, methanol and toluene. Using this technique, the major contaminants of each …show more content…

They are mainly Class-1 (Solvent to be avoided), Class-2 (Should be limited in drug substance) and Class-3 (less toxic and low health hazard to humans). The Class-1 type of the solvents is hazardous, known human carcinogenic, strongly suspected carcinogenic and also causing environmental hazards. The class-2, types of solvents are nongenotoxic animal carcinogen or possible causative agents of other irreversible toxicity viz neurotoxicity or teratogenicity. These types of solvents are suspected of other significant but reversible toxicities. The Class-3 solvents are with low toxic potential, low toxic potential to humans and no health based exposure limit is needed. The detailed accounts on the solvent list, its class and concentration limit in parts per million (ppm) is furnished in Table 5 …show more content…

The raw materials are relatively manufactured to much lower quality requirement than a drug substance. Hence, it is easy to understand why they can contain a number of components that can turn affect the purity of drug substances. During synthesis of product having chances to generate impurities, because number of reactions can occur concurrently. Be remembered that base to salt or acid to salt conversion could also generate new impurities [49]. For example, In the synthesis of ethynodiol diacetate in final step is diacetylation of ethynodiol, during reaction reactivity of secondary 3-hydroxy group is much higher than that of tertiary 17-hydroxyl a impurity is formed (ethynodiol-3-acetate). In the synthesis of pipecuronium bromide (2β, 16β-bis-(4-dimethylpiperazino)-3α,17β-diacetoxy-5α-androstane dibromide) is diacetylation of 3α,17β-hydroxy derivative and impurity is formed 17β-monoacetyl derivative [57]. Impurity profiling experiment on ecstasy tablets by GC-MS, and MDMA (3, 4-methylenedioxy-methamphetamine) samples showed impurities in intermediates via reductive amination route [58,

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