[Studies on residue on ignition test in JP].

The Residue on Ignition Test specified in General Tests, Japanese Pharmacopeia is a method to measure the weight of the residual substance not volatilized when the sample is ignited under a constant condition. Generally, this test is intended to determine the content of inorganic substances contained as impurities in an organic substance, and, occasionally, to determine the amount of inorganic substances contained as components in an organic substance. Our laboratories have adopted this test method for the above two purposes in the case of the quality control for drug substances, synthetic intermediates, starting materials in the course of drug development. Some validation studies have been conducted for this test in order to clarify the quantitation limit in the case of an application for the former purpose, and trueness and precision in the case of the latter purpose. Consequently, the quantitation limit was determined as around 0.50 mg. The amount of sample should be determined based on this quantitation limit (mg) and the level of quantitation limit (%) or that of specification limit (%) should be considered from the view point of each testing purpose. The test method was also confirmed to have a good trueness and precision as the determination method for an alkaline salt, such as sodium, potassium or calcium salt, of organic compounds, as long as the test is operated with great care not to scatter the content out of crucible during ignition to incineration.