Reference Standard Preparation and Characterization

A reference standard material is defined as highly purified compound that is well characterized by FDA (US Food and Drug Administration), and highly characterized specimens of drug substances, excipients, reportable impurities, degradation products, compendial reagents, and performance calibrators by USP (US Pharmacopeia). Reference standards are used to determine quantitative data (such as assay and impurity), qualitative data (such as identification test), and calibration (such as melting point standard). Therefore, the quality and purity of the reference standards are crucial to achieve scientifically valid results.

Creative Biolabs provides reference standard preparation and characterization service to ensure the smooth progress in drug discovery.

If the reference standard material is not available from a commercial source, it should be prepared by synthesizing. The reference standard materials are usually prepared according to the following rules:

• Fully characterized high purity neat materials and high purity diluents
• Careful assignment of chromatographic purity by multiple methods
• Analysis of residual impurities including water, inorganics and solvent
• Validation process ensuring consistency and accuracy of solution concentration purity and stability
• Qualified balances in their installed state with minimum weighings set for <0.1% relative error
• Traceability to SI units
• Uncertainty statement encompassing all aspects of standard preparation from neat material characterization to solution preparation.

For APIs, the materials may start out as a lot of drug substances with sufficient purity to be designated as the reference-standard materials, or they may require further purification. Minimal required tests for initial characterization are typically performed by using the following tests:

• Organic impurity: UV detection is the most usual and widespread detection principle in high performance liquid chromatography (HPLC). Many (or even most) organic impurities are suitable for HPLC absorption in the UV, whereas many solvents, including the ones used for reversed-phase separations, are transparent in the UV. If necessary, the wavelength range can be easily expanded to the region of visible light for the detection of colored analytes.
• Metals impurity: Inductively coupled plasma mass spectrometry (ICP-MS) is a type of mass spectrometry which is capable of detecting metals on non-interfered low-background isotopes.
• Noncombustible impurity: The residue on ignition/sulfated ash test uses a procedure to measure the amount of residual substance from a sample. This test is usually used for determining the content of inorganic impurities in an organic substance.
• Residual solvents: Gas Chromatography – Flame Ionization Detector (GC-FID) is a very common analytical technique that is widely used in the pharmaceutical research. The FID is extremely sensitive to hydrocarbon impurities in the hydrogen and air supply for the flame, which is the reason why GC-FID used for detection of residual solvents.
• Water content: Karl Fischer titration is a classic titration method that uses coulometric or volumetric titration to determine trace amounts of water in a sample. There are several practical advantages of Karl Fischer titration that it holds over other methods of moisture determination, such as accuracy, speed and selectivity.
• Structural confirmation: NMR, LC–MS, or FTIR are commonly used for structural confirmation of different compounds.

Experts and chemists at Creative Biolabs continue to develop synthetic approaches to reference standard. We also have kinds of raw materials and intermediates for the synthesis of reference standard. After completion of the synthesis, the compounds are characterized using various techniques (HPLC, ICP-MS, GC-FID, NMR, LC–MS, and FTIR). If you have any question about reference standard preparation and characterization, please contact us without hesitation.

For Research Use Only.