5 Applications of Impurity Reference Standards (IRS)

Let’s first start by understanding impurity reference standards.

For the safety of the medicine, impurities are recognized. In addition, their content is Application Programming Interface (APIs) has to be managed following ICH and FDA guidelines via an Impurity Reference Standards (IRS). You must purchase it from a reliable impurity standards supplier.

The applications of IRS are divided into two categories: qualitative and quantitative.

1. Qualitative

● System suitability test - This test is frequently utilized in pharmacopoeial approaches, but they are also critical in in-house analytical procedures. In order to test the right performance of the method in its current setup, two or more analytes, often the API and one or more contaminants that elute rather close together in the normal HPLC process, must be separated sufficiently.

●Peak identification - Mass spectrometry (MS) is frequently used to determine the molecular mass of unknown impurity peaks discovered during process/method development. These investigations yield a preliminary molecular structure that can be validated using a reference standard.

2.    Quantitative

●Limit test - It is a semi-quantitative application. Limit tests are frequently seen in pharmacopoeial monographs, and they can also be devised for in-house impurity quantification. Limit tests for specific impurities are also conducted, often against a solution of the impurity under examination.

●The direct use of the IRS - This is how an IRS is typically used in normal quality control. It's mostly used for specific impurities, and it is also used a lot when the impurity's content is expected to rise with time.

●Quantification of impurity via relative response factors (RRFs) - RRFs are typically developed with the help of IRSs, which establish a defined correlation between the analytical response of an adequately diluted solution of an API reference standard and the IRS solution. This relationship is stated in the RRF value, which, when correctly assigned, can be utilized to determine the impurity concentration in specific conditions.

To conclude, an IRS designed for quantitative objectives may also be used for qualitative ones. If you are not sure which IRS will go, you should start with quantitative material to ensure consistency in results. Of course, before even beginning for application, procure these standards from the best pharmaceutical reference standards supplier.