If stoppered test tubes are to be used in processes that require sterility, the manufacturer’s declaration alone may not be sufficient during an audit. The auditor will need documents that make it possible to link a specific batch to control results, the sterilization process, and the required sterility assurance level. Therefore, before purchasing or qualifying the material, it is worth checking whether a CoA, bioburden data, and process validation documentation are available. It is also important to verify whether the information in these documents is consistent with the markings on the packaging.
What sterility requirements must stoppered test tubes meet?
Stoppered test tubes intended for applications requiring sterility should have a documented process ensuring an appropriate SAL level and control of the microbiological load before sterilization. For products labeled as sterile, an SAL of 10⁻⁶ is used. This means a theoretical probability of 1:1,000,000 that, after the process is completed, at least one viable microorganism remains on a sterilized unit.
For an audit, however, what matters is not the SAL value itself, but how it is justified. The documentation should make it possible to trace:
- the relationship to bioburden,
- the sterilization method used,
- the validated process parameters.
Standards and regulations concerning SAL and bioburden
Bioburden means the microbiological load of a product before sterilization. Its determination is associated with the requirements of ISO 11737-1. In the context of medical devices, EN 556 is also relevant, while in the area of medicinal products, pharmacopoeial requirements and guidelines for the manufacture of sterile products apply.
The documentation may also include references to:
- Ph. Eur. 5.1.1,
- FDA 510(k),
- EMA Annex 1.
Selecting the appropriate requirements depends on the product’s intended use, the market, and the regulatory status of the given item.
Documentation confirming sterility: CoA and other certificates
The Certificate of Analysis, or CoA, relates to a specific product batch and confirms the results of controls performed in accordance with defined specifications. In the case of sterile stoppered test tubes, it should enable unambiguous identification and indicate the test methods used and the results obtained.
Audit documentation may also include bioburden reports, sterilization validation confirmations, declarations of conformity, and documents related to the quality system. If sterility depends on closure integrity, the results of leak testing or integrity testing of the tube–stopper system are also important.
How should the Certificate of Analysis and bioburden reports be interpreted?
The first step in interpretation is to compare the batch number on the CoA with the marking on the packaging. Next, it should be verified which tests were performed, according to which method, and what results were obtained. The information “pass” alone may be insufficient if the qualification procedure requires specific values or methodology to be provided.
A bioburden report should specify the sampling method and the determination method used. The result may be presented as a CFU count, i.e., colony-forming units. For certain pharmaceutical applications, limit values are adopted depending on the type of product, so a limit should not be automatically applied to every type of test tube.
The document issue date, validity period or retest date, and authorization by the person responsible for batch release are also important. A CoA documents results relating to a specific batch and does not replace documentation concerning subsequent product storage.
What does an auditor expect when verifying the sterility of stoppered test tubes?
The auditor primarily checks whether the history of a specific batch can be reconstructed. Therefore, the documents should be mutually consistent, and the numbers, product identification, and process data must correspond to the physical markings on the packaging.
The verification may include:
- a CoA assigned to the correct batch,
- bioburden test results,
- sterilization process validation documentation,
- information on cycle parameters such as time, temperature, or radiation dose, depending on the method used,
- documents confirming closure integrity,
- data concerning the storage of sterile products,
- documentation of supplier qualification and of the materials used to manufacture the tube and stopper.
Additionally, the auditor may check whether the bioburden level is monitored regularly, whether sterilization parameters have been validated, and whether revalidation rules are in place. In the case of a product whose sterility depends on a tight closure, it may be necessary to present evidence confirming the integrity of this system.
Problems during an audit often result from:
- missing documents,
- inconsistent batch numbers,
- overly general declarations.
The risk of nonconformity is also increased by the lack of documented justification for bioburden limits and by improper storage conditions after opening the outer packaging.
Therefore, before an audit, it is worth preparing the documentation in a format that reflects the traceability path. From a specific batch of test tubes, through control and bioburden results, to sterilization validation and storage conditions. In the case of stoppered test tubes offered by the plastic laboratory consumables manufacturer Noex Labware, the availability of such a set of documents makes it much easier to demonstrate that the declared sterility has a documented basis.
Key information on the sterility of stoppered test tubes
- SAL 10⁻⁶ is the sterility assurance level used for products that must be labeled as sterile, but it should be supported by appropriate process validation.
- Bioburden defines the microbiological load before sterilization and must be controlled in accordance with the appropriate methodology.
- A CoA should enable identification of a specific batch and present the relevant results and test methods.
- During an audit, consistency across the entire documentation set is essential: from the lot number and CoA to sterilization validation, closure integrity, and storage conditions.
FAQ
What documents are required during an audit of the sterility of stoppered test tubes?
During an audit, a CoA, bioburden test results, and documentation concerning the SAL level and sterilization process may be required. The auditor may also review documents confirming compliance with the relevant standards and quality system requirements.
What is SAL and why is it important for stoppered test tubes?
SAL, or Sterility Assurance Level, defines the level of assurance that a product is sterile after the process is completed. For test tubes intended for applications requiring sterility, it is important to document the level appropriate for the intended use.
What is the significance of bioburden in the context of test tube sterility?
Bioburden defines the number of microorganisms present on a product before sterilization. Its control is part of the assessment and validation of the sterilization process.
Do stoppered test tubes need to have a CoA certificate?
A CoA is an important document confirming the control results for a specific batch if it is required as part of product qualification or the quality system. Its scope should correspond to the requirements of the given application and process.
How should you prepare for an audit regarding the sterility of stoppered test tubes?
You should gather current CoAs, bioburden reports, sterilization validation documentation, and data concerning batch identification and storage. It is also worth checking whether the documents comply with the requirements applicable to the intended use.