The early recognition and therapeutic use of native peptide products has paved the way for the development and production of synthetic peptides, which represent a significant area of growth in the biopharmaceutical sector. By leveraging bioinformatics, computational approaches, and molecular modeling, synthetic peptides can be designed with optimized properties tailored for their intended functions. These properties may include cyclization and other structural features unattainable through recombinant technologies, such as incorporating D-amino acids.
The production of peptides and the associated analytical challenges are acknowledged by both the EMA (1) and FDA (2) . As previously mentioned in this blog series, full structural characterization of peptides is crucial. Additionally, regulatory bodies emphasize the importance of impurity analysis at both the final product stage and in-process stages. The EMA even identifies purity as “one of the most important critical quality attributes.”
Understanding the Origins of Impurities
Process-related impurities can originate from two main sources:
It is therefore important to be mindful of the precise processes and chemicals involved in the manufacturing so that impurity analysis can be meaningfully considered and investigated. For recombinant peptides or those derived from natural sources, it is essential to consider “upstream” processes that may introduce impurities, such as host-cell contaminants or residual components from cell culture.
Discover how early analytical strategies enabled the structural characterization of human CGRP, a potent vasodilator. This foundational Nature paper offers valuable insights into peptide analysis techniques still relevant today.
Both the FDA and EMA refer to ICH Q3C (3) when evaluating residual solvent levels (e.g., DMF, DCM, acetonitrile). The guideline outlines general expectations and solvent-specific considerations, emphasizing that gas chromatography (GC) is commonly used for this analysis. At BioPharmaSpec, headspace GC-MS (Figure 1) is utilized due to its high sensitivity, allowing accurate detection of residual solvents that may be present in a product.
Heavy metals are covered by ICH Q3D (4) and are recognized and referenced by the FDA and EMA. These impurities often arise from equipment or reagents and are of concern due to their toxicity and ability to facilitate degradation. For this reason, monitoring throughout the production process is essential. Inductively Coupled Plasma Mass Spectrometry (ICP-MS) is particularly useful for heavy metal detection given its high sensitivity, which enables the detection of trace amounts (down to parts per billion), covering a broad range of metal contaminants.
Effective peptide manufacturing requires careful selection and control of raw materials to minimize potential impurities. These materials need to be sourced with due consideration for their own impurity profiles. The EMA guideline on synthetic peptides (1) advises against the use of amino acids derived from human or animal sources to reduce the risk of transmissible spongiform encephalopathy agents. For the raw materials used in the process, impurities to consider include stereoisomers, unprotected amino acids along with their own residual solvents and heavy metals. Each of these can significantly impact product quality.
Mass spectrometry techniques, such as GC-MS and LC-MS, are essential tools for detecting these impurities, providing the high sensitivity needed to identify trace contaminants. Additionally, several other components, like buffer salts, detergents, additives, and solid-phase resin chromatography materials, can introduce unwanted impurities if not properly controlled.
Non-peptide-based components intended for conjugation to peptides, such as linkers or targeting moieties, also require due consideration. The EMA guideline (1) and ICH Q11 (5,6) emphasize the need to assess these components separately to ensure overall product quality.
For recombinant peptides, the removal and monitoring of upstream contaminants, such as host cell proteins (HCPs) and host cell DNA (HCDNA) are particularly important.
Container closure systems should also be evaluated through extractable and leachable studies, as these can introduce additional impurities into the final peptide product.
Process-related impurities in peptide manufacturing are a key consideration for both the FDA and EMA. These impurities can arise not only from chemicals used in the manufacturing process but also, crucially, from the raw materials themselves. For recombinant peptides, upstream contaminants of biological origin must also be accounted for.
Mass spectrometry, in its various forms, remains a highly effective technique for detecting impurities due to its exceptional sensitivity and selectivity. It can identify specific components even at the isomeric level, where the mass of the impurity is identical to the mass of the main component.
Whether you're navigating early-stage development or preparing for regulatory submission, BioPharmaSpec offers expert-driven peptide analysis services to help you meet structural characterization requirements with confidence.
Contact our scientists today to discuss your peptide project and receive a tailored analytical strategy.
