Extractables Protocol


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Analytical Methods

How can we compare data from different labs when the column is not exactly the same or determinant parameters not harmonized?

We have included additional standards to demonstrate similar chromatographic range using different columns and instruments.  The widest chromatographic range is desired.  That is also the reason for specifying the standards.  This way we can assess relative retention compared to known standards for comparison.  This is also mitigated if compounds are identified (even tentatively) above the suggested reporting threshold.

Why is validated quantification requested while the USP<1663> applicable to primary packaging (therefore with more critical applications) consider that quantity estimation is acceptable?

We are not proposing validated quantitation of compounds. We are proposing that observed compounds be quantitated against reference or authentic material which may also be used for compound confirmation.

Should LC-MS be used as screening method or as target analysis?

The LC-MS should be used as screening to observe unexpected compounds. Potential targets can be included in the analysis to help confirm and quantitate matching compounds.

Does the LOD/LOQ have to be determined for each identified compound? For UV signal and MS signal (in case of LC-MS-UV), SIM mode or screening mode for each compound?

The minimum requirement is to determine LOD/LOQ for the standards. The LOD/LOQ does not need to be determined for each identified compound, but it is good to have because the response from each compound is different. Screening mode is generally proposed for the analysis to observe unexpected compounds that are present.

Does the LC-MS UV methodology need more details?

We do not want to be too rigid since many labs have acceptable methodology but want to include enough detail to ensure acceptable results are obtained.

Does the LOD/LOQ have to be determined for each extraction medium (for all methods)?

Yes. We expect due diligence for the analytical methods and a lab would be very remiss not to determine LOD/LOQ in each matrix to be analyzed regardless of whether or not they are following the BPOG Protocol This is a common analytical lab practice.

LLE procedure may not work as described for each extraction medium. It is important to define a pH shift for the low and high pH solvents. What does BPOG think about this?

The selection of the extraction solvents was intended to encompass the widest range of potential extractables relevant to our processes (following the 80/20 approach).  The extractable profile of the solvents overlap by design to ensure this coverage is thorough.  Therefore, we acknowledge that there are some compounds whose extraction efficiency is improved by pH adjustments to the extraction solvents. However, since the goal is to gain a complete picture of the extractables via all of the solvents and time points, the loss of efficiency in one solvent condition is compensated with a more complete picture by the other solvents.  If a lab prefers to pH adjust then that is fine and this should be specified within the report.  If there are specific extractables which a company expects to be present and are known to require pH adjustment then we are supportive of this approach as long as the adjustment and rationale are spelled out in the report.

Can you clarify for LC-MS if internal or external standards are to be used for semi quantitation? Is it important to know due to matrix effects?

Internal standard is typically used to adjust for ionization efficiency effects and external standard for semi quantitation generally.  It is acceptable for individual lab to take either approach as long as they are qualified and scientifically justified.

What is DL for ICP-MS?

The DL will be different for each element. We are proposing a target of 20 ppb which may not be possible for all elements.

The real work for the screening of extractables is done by the GC-MS, but unfortunately no pure organic solvent will be used. All proposed media need sample preparation which means a lot of analytical information will be lost due to sample preparation. What are your thoughts?

An extractable profile for pure organic solvent is sometimes overkill and not as representative of what is relevant to the processes which BPOG members have been concerned with. Therefore, using a pure organic solvent is not relevant and not needed for our applications. On the other hand, we welcome evidence for the “loss of analytical information”. Note that an organic solvent and the solvents proposed would not extract the same compounds.  It would be interesting to know if there is any data related to exactly what analytical information is lost via sample preparation.

At a recent conference presentation your proof of concept study had the following bullet point on a slide for your samples. • Analyzed immediately where possible, frozen at =-20C otherwise. We have 3 major concerns about this: 1. Water will freeze at -20, organics may not, this will affect solubility with no guarantee that the extractable analytes will go back into solution once precipitated out, the example of the 5M salt could be worse as it may all crash out and may carry organics with it. Also, the 50/50 ethanol may partition, uniformity of solutions is in question. 2. Storage vessel? All extracts are typically stored in glass to avoid plastic leachables – freezing liquids in glass is not advisable. 3. Lab programs can generate 100 Liters of extracts – This requirement could be ill advised due to lack of available -20oC space by the laboratories.

We recognize your valid concerns and refrigeration may be better for short term storage of samples, especially large volumes of samples. Sample containers should be inert glass, teflon or stainless steel.

We also recognize the sample storage issue is a big one with just as many opinions (and probably as much “data that can’t be shared” due to supplier NDAs ) as our extractable studies themselves.  It is always a point of consideration, because the ideal would be real time analysis but that is not practical.  We can see scientific justification for both freezing and storage at 2-8C.  Your points about precipitation and phase separation are valid, but storage at 2-8C may lead to degradation of extractables (oxidation/hydrolysis, etc.) or loss of volatiles, which are also valid.

Our base line, is that barring a perfect solution, we leave it to the analytical labs to justify their approach as reasonable.

We will remove this reference from future presentations and as you know, freezing samples is not mentioned in the extractables protocol.

We will also review and update the language in our forthcoming leachables guide to allow either short term storage at -2-8 and say if and when longer term freezing is really the only option.

Scope and Application

What is the expectation with regard to quality sign off of Extractables and Leachables data?

The Bioprocessing industry is governed by cGMP. As such any data that are used to make quality decisions must meet minimum data integrity and traceability standards. It is the expectation of BPOG companies that data provided by suppliers qualified for providing polymeric components and Single Use Systems are generated in such a way as to be compliant with these standards. Whilst it is not necessary that data be generated to cGMP, it is expected that the direct supplier of the Single Use Equipment takes ownership for the study design and review of the data. Typically this will require technical, functional area input and oversight from the supplier Quality Unit.

For clarity, where a third party such as a CRO has performed extractables testing, it is not sufficient for that report to simply be passed along to the BPOG member company. It remains the responsibility of the company directly supplying the SKU to the BPOG member company to design, execute and report the testing with oversight from their quality group and within the quality policy of their organisation. Reporting should be done through a mechanism that includes quality sign off by the vendor of the SKU to verify and take responsibility for the accuracy of the information provided as would be the case for outsourced testing reported on a certificate of analysis.

This requirement will not apply retrospectively to studies that are already underway or have been completed

I have heard that there is a push to have extractable testing completed for ALL components by the beginning of 2017. This appears to be a change from the Letter of Intent we have received from several of our vendors. In that letter it states “The extractables user requirement is not retrospective. i.e. components that you currently supply to our company will already be qualified and validated by end users and therefore at this stage additional extractables testing will not be required for these materials.”

We have now changed the wording in the template letter of intent as a result of your question so thank you for raising this.
There is no push for ALL components to be all tested by Q1 2017. The key word is “new” – by this we mean new components that are introduced and existing components in the market that a supplier is looking to sell to new customers. It also applies when an existing component changes its material of construction or method of manufacture and requires retesting – in effect the component should be treated as it is new and must be retested in line with requirements. Also, if a component has been used and qualified for a current drug that does not mean it is qualified for a new drug which the user is planning to manufacture
The question for a supplier to ask should be: “is this a custom made product for a specific customer for existing drug manufacture or is it one we plan to sell to new customers or to the current customer but for manufacture of a new drug?”
It would of course make sense for each supplier and user to review what they currently supply and confirm what testing is required or not.


Conductivity analysis has been requested by a customer. Conductivity is not mentioned in either the BPOG article or the subsequent Standard User Requirements (SUR).Is this required for all BPOG submissions or just for this customer?

This an optional test that is not required by all BPOG members but as in this case, it may be requested by a user where they deem it necessary for their product/process. In such cases it will be for the user and supplier to reach agreement on this testing and funding.

Is it true that in addition to the requirement that extractions begin within five weeks of gamma irradiation, there is a new requirement not to begin the extractions until the device has aged for 3 weeks following this? Is this a new requirement? If so, what is the logic for this aging step? As stated in the BPOG article the reason for the 5 week requirement for fear of “degassing of volatile organic compounds from the gamma-irradiated components”. Would starting the extractions as soon as possible yield a worse case profile, which is the objective of the study?

 This is not true. There is no requirement for the component to have aged three weeks after gamma irradiation. Any start date before the end of week 5 after irridiation is acceptable. .

In earlier discussions with BPOG members, it was stated that there would be periodic FAQs detailing all the questions and answers posed on the BPOG protocols. Is this still being planned?

Yes .In addition to FAQs we will share on this website, the team also plan to run webinars for suppliers. Suppliers  are very welcome to contact the team to ask for a meeting and you can submit questions through the form at the bottom of this page.
BPOG team members will also feed back questions and issues they pick up through their regular contacts with suppliers that would be helpful for the team to address.

Will a user pay for extractables testing if the request falls outside the BPOG protocol?

The instances where specific companies require additional data not specified in the BPOG protocol should be rare.  This is a key advantage of adopting the BPOG protocol.  Also the family based approach espoused by the protocol should minimize the amount of testing to be required.
The choice of solvents and time-points dictated in the protocol was arrived at after careful thought, testing which had used multiple solvents, time-points and consideration of a wide variety of biologics processing conditions for a representative range of bio-pharmaceutical products.  These choices bracket the processing conditions of the BPOG members.  The views of companies which make 80 to 90 per cent of all bio-pharmaceutical products were involved and are in agreement with the BPOG protocol.
Exceptions may arise from time to time.  In these cases, agreement should be reached between the SUS supplier and the customer regarding costs.

Is it up to the SU system supplier to collate and submit the extractables data from each component in that system? Can they ask a component supplier to send this direct to the user if they are unwilling to disclose their data to another supplier?

The SUS supplier is the direct interface with their customers (i.e., the bio-pharmaceutical manufacturer) and as such is responsible for ALL aspects of quality for all components relating to the SU system they are selling.  This includes assembling the required information regarding the extractables test data in the standardized format identified in the BPOG protocol and Single Use Requirements (SUR) package sent to each single use system supplier.
When required, the SUS suppliers need to have clear quality agreements in place with their own suppliers, stipulating the requirement for these data.  The data can come from the supplier to the SUS manufacturer – the key point is that the data are provided.  If these data are unavailable then the SUS supplier should initiate extractable studies of their own in line with the BPOG protocol.

Regarding depth filters for cell harvest or removal of cell debris. The depth filters are built into a bag, which is supplied by a renowned company from the SU. All plastic parts are USP VI and the sheet we used are our own pyrogen and low ion sheets. The sheets itself are built from cellulose, sometimes DE and a resin binder.   Do depth filters need to meet BPOG standardized protocol for extractables testing?

  • Class VI is the minimum requirement.
  • BPOG protocol is to be used by suppliers with their judgment about their products intended use in the bio-production  process . Tests should be performed using two lots as stated in the protocol. Note that several suppliers have done such studies before (when the BPOG protocol was not yet generated) and in addition to organic compounds, inorganic elements were an important part of the study
  • Suppliers do need to test the filter housing, including gaskets/o-rings etc. only and should use all six solvents at time zero and one day time points since depth filters in some cases are also used in late steps of the process. If any solvent is incompatible and cannot be modified to be compatible, then it can be omitted. The supplier should provide justification for doing so.
  • We recognize that depth filters see mostly neutral culture, so water and salt would be required in all cases.
  • We also recommend to perform NVR on 50 per cent Ethanol and WFI extracts. TOC on WFI extract. There is a need to watch for mass balance, as the major extractables will not be detectable by our recommended methods. We recommend adding HPLC/ELSD analysis for non-volatile extractables. As above, perform test on T-0 and 24 hours with preform flow through set up (flow from bottom up with a reservoir at the highest point) where no flushing is necessary. If dynamic soak is utilized, flush no more than half of the minimum recommended flush volume to push out the air and wet the filter material.



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