MS & NMR Center / Alfa Chemistry
Pharma Support

Isolation and Identification of API Impurities

Isolation and Identification of API Impurities

In pharmaceuticals, impurities are first and foremost a quality issue, as they have the potential to impair the efficacy of the drug. Secondly, impurities may also lead to safety issues. However, it is a generally accepted fact that some impurities are unavoidable and will be present in trace amounts. Therefore, the identification and establishment of limits for impurities in active pharmaceutical ingredients (APIs) has become an important initiative for governments and the pharmaceutical industry. The International Conference on Harmonization (ICH) was established in the 1990s to harmonize technical requirements for the registration of pharmaceuticals in the European Union, Japan and the United States. According to ICH guidelines, it is recommended to identify and characterize all impurities present at 0.10 % or higher levels.

With cutting-edge technology platforms and experienced technicians, the MS and NMR center of Alfa Chemistry can provide excellent analytical services for the isolation and identification of impurities in APIs. Our range of technologies includes but is not limited to LC-NMR, HPLC-NMR, HPLC-NMR-MS, GC-MS and LC-MS. These techniques are highly sensitive and accurate, allowing us to detect and identify trace amounts of impurities.

Our Services

The identification of impurities in APIs is a key analytical activity in the drug development process. Alfa Chemistry has the ability to isolate and identify the following impurities related to APIs.

  • Organic impurities

Organic impurities are the most common impurities in every API. They are formed during the synthesis of the API. The related impurities in the synthesis process can be derived from the starting materials, intermediates, reagents, ligands and catalysts used in chemical synthesis, as well as by-products from the side-reactions of the chemical synthesis [1].

Organic impurities

  • Inorganic impurities

In most cases, inorganic impurities are introduced from the synthesis process of the drug substance or are present as impurities in the excipients. Inorganic impurities are usually known and identified and include mainly the following.

  • Heavy metals: These include elements such as arsenic, lead, cadmium, mercury, and others, which can be toxic to humans even at very low levels.
  • Inorganic reagents and catalysts: These are chemicals used during the manufacturing process of the API that may be present as impurities. Examples include sodium hydroxide, sulfuric acid, and platinum.
  • Residual solvents

Residual solvents are organic volatile chemicals used or produced in the manufacture of drug substances or excipients or in the preparation of drug products [1]. They pose a threat to human health. ICH classifies residual solvents into the following three categories based on their level of toxicity.

  • Class 1 solvents: These are known to be the most toxic solvents and are considered to pose a significant risk to human health. Examples include benzene, carbon tetrachloride, and 1,2-dichloroethane.
  • Class 2 solvents: These are solvents that have a moderate toxicity level and may pose a risk to human health if exposure is not properly controlled. Examples include ethanol, isopropanol, and methylene chloride.
  • Class 3 solvents: These are solvents that have low toxicity levels and are considered to pose a minimal risk to human health. Examples include acetone, ethyl acetate, and toluene.

Why Choose Us

Why Choose Us

Alfa Chemistry is well aware that various regulatory authorities, such as the ICH, the United States Food and Drug administration (FDA), and the Canadian Drug and Health Agency (CDHA) are emphasizing the importance of impurity identification in APIs. At Alfa Chemistry, we are committed to providing customers with high-quality services and strive to exceed their expectations. Our expertise in API impurity identification can help pharmaceutical companies ensure the safety and effectiveness of their products and meet regulatory requirements.


  1. Qiu, F.; Norwood, D. L. Identification of pharmaceutical impurities. Journal of liquid chromatography & related technologies. 2007, 30(5-7): 877-935.

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