Residue On Ignition Test

Organic drugs charred by incineration, then add sulfuric acid wet, low temperature heating to sulfuric acid vapor removal, at high temperature (700 ~ 800℃) incineration to complete ash, so that the destruction of organic material decomposition into volatile substances escape, non-volatile inorganic impurities (mostly metal oxides or salts) become sulfate, known as incineration residue. The residue on ignition check method is used as an indicator to control the quality of API. Among them, volatile inorganic drugs such as hydrochloric acid, ammonium chloride, by heat volatilization or decomposition, residual non-volatile impurities, so also according to the above method to check the burning residue.

On the Burning Residue Limit of Drugs

Drug incineration residue limit is generally 0.1% to 0.2%, according to the drug specified in the incineration residue limit to determine the amount of test samples taken. If the limit is 0.1%, sampling about 1 g; if 0.05%, sampling about 2 g; in more than 1%, sampling can be in 1 g or less. In the case of precious drugs or insufficient number of test products, the sample size can also be reduced as appropriate. When the results are judged, the value of incineration residue is less than or equal to the limit, it is judged to be in accordance with the provisions; its value is greater than the limit, it is judged not to meet the provisions.

Our Services

CD Formulation offers a professional drug residue on ignition test, which assesses the quality of a drug by heating the drug to char and then ashing it.

Operation steps

• Constant weight in an empty crucible

Take a clean crucible and place it in a high-temperature furnace, cover the crucible cover obliquely on the crucible, heat it to 700-800℃ for about 30-60 min, stop heating, wait for the temperature of the high-temperature furnace to cool down to about 300℃, take out the crucible, place it in a suitable desiccator, cover the crucible cover, let it cool down to room temperature, and weigh the crucible precisely.

• Weigh the test article

Take the specified weight of each species, place it in the crucible which has been incinerated to constant weight, and weigh it precisely.

• Charring

Place the crucible with the test article on the electric furnace and burn slowly until the test article is all charred black and no longer smokes, then cool to room temperature.

• Ashing

Add sulfuric acid drop by drop, make the charcoal all wet, continue to heat on the electric furnace until the sulfuric acid vapor is removed, and the white smoke disappears completely. Place the crucible in a high-temperature furnace, cover the crucible with a slanting lid, and incinerate at 700-800℃ to completely ash the test article.

Matters Requiring Attention During Operation

• The test article should be heated slowly first.
• Use the crucible tilted until it is completely charred to avoid sudden expansion and escape of the test article.
• Add sulfuric acid after charring and cooling, and heat at low temperature to avoid splashing of the test specimen at too high a temperature, which may affect the determination results.
• Be sure to evaporate and remove sulfuric acid before placing the crucible in the muffle furnace to prevent sulfuric acid vapor from corroding the furnace chamber and causing leakage accidents. Fluorine-containing drugs are corrosive to the porcelain crucible, so platinum crucible should be used.

About CD Formulation

CD Formulation's business covers all aspects of drug formulation, drug ingredients, drug development, drug testing, drug optimization, etc. We provide one-stop integrated services from pre-clinical to commercial manufacturing for our global pharmaceutical and biotech partners. If you have a requirement about our services, please contact us by phone or email, our colleagues will reply to you within three working days.