| <!DOCTYPE html> |
| <html lang="en"> |
| <head> |
| <title>Efficiency-COU</title> |
| <link rel="stylesheet" href="../../static/styles.css"> |
| <meta charset="UTF-8"> |
| </head> |
|
|
| {% extends "base.html" %} |
| {% block content %} |
|
|
| <h2 id="context-of-use-cou">Context of Use (COU)</h2> |
| <p>The extraction efficiency module of the CHemical RISk calculator |
| (CHRIS) allows the user to compare the theoretical impact of extraction |
| conditions, sample geometry and material properties on extraction |
| efficiency and extraction solvent concentration. These assessments can |
| assist device manufacturers and test laboratories by providing immediate |
| feedback on “worst-case” device geometries and extraction conditions |
| based on the endpoint of interest. This information can support reducing |
| the number of configurations that need to be tested for a device product |
| line to support biocompatibility evaluation of a medical device. |
| Further, the tool can potentially be used to guide the development of |
| alternative extraction test protocols.</p> |
| <p>The CHRIS - extraction efficiency module outputs a predicted |
| extraction efficiency (mass of extractable released over the initial |
| mass in the test article) and relative extract solvent concentration |
| (concentration in the solvent over the initial concentration in the test |
| article) based a non-steady state mass transfer model. The model |
| requires eight (8) input fields that describe the extraction conditions, |
| test article geometry, and test material system, including the mass, |
| density and surface area of the test article, extraction solvent volume, |
| extraction time, number of iterations, and the diffusion and partition |
| coefficients that describe the system of interest. For additional |
| details on the model please see this <a |
| href="https://www.sciencedirect.com/science/article/pii/S0273230023000739">article</a>.</p> |
| <p>The tool is limited by the assumptions upon which the model is based. |
| The salient limitations are enumerated below:</p> |
| <ol type="1"> |
| <li>The extractable is macroscopically homogeneous within the matrix. |
| Therefore, the output is only applicable to compounds that are |
| introduced either intentionally or unintentionally during synthesis |
| (e.g., residual monomers and oligomers, catalysts, initiators) or |
| compounding (e.g., stabilizers, antioxidants, plasticizers). The model |
| is not appropriate for surface residuals from processing, cleaning, and |
| sterilization.</li> |
| <li>The solvent is “perfectly mixed”. This should be a reasonable |
| assumption provided the samples are adequately agitated over the |
| timeframe of the testing. However, this assumption may not be |
| appropriate if sufficient agitation is not applied and a signficant |
| boundary layer develops that slows the release rate or if the extraction |
| is conducted under flow conditions.</li> |
| <li>Possible chemical reactions are not considered. Therefore, if the |
| polymer matrix undergoes substantive degradation during the extraction |
| test, the predictions may not be relevant. Further, the model does not |
| consider the potential for individual extractable compounds to degrade |
| over the selected timeframe.</li> |
| <li>The test article is comprised of a single polymer matrix. In |
| practice, complex devices may be comprised of multiple components and/or |
| polymer matrices. In these scenarios, careful consideration of the |
| potential contributions of each material constituent of the test article |
| to the extractables profile is critical when attempting to leverage the |
| model predictions.</li> |
| </ol> |
| {% endblock %} |
