Webinar Q&A follow up: general practices for critical reagent usage in bioanalytical laboratories
Thank you to everyone who attended our webinar ‘General practices for critical reagent usage in bioanalytical laboratories’ in association with Frontage Laboratories (PA, USA). Below are responses from event host Santosh Shah to the questions posed by our audience during the live event. We hope this is a useful resource and thank those who submitted these thoughtful questions.
(Q) What approach would you use to bridge reference standards if you want to compare head-to-head, old, and new curves and full complement of quality controls (QC): LLOQ, LQC, MQC, HQC, ULOQ?
(A) We set up two sets of plate controls (i.e., one set = one set of standards and two sets of QCs) each prepared with two different lots separately, and check the following results:
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- For each set, if standards and QCs meet the acceptance criteria.
- If one lot of prepared QC meets the acceptance criteria in comparison to another lot of prepared standards.
(Q) Preparing from an old and new batch of reference standards will not fit on a 96 well plate, if there is the need to include three replicates of each. Is just running one or two replicates a valid approach so all five levels of QCs can be tested?
(A) Our most common practice is to use two replicates. If three replicates are required, we use two plates to complete the comparison of reference standards.
(Q) Do you have a standard expiry assigned to different types of critical reagents, since often the stability is not known initially? Would you be willing to share your approach for being able to assign the expiry or retest/recert dates initially?
(A) For critical reagents acquired from external sources, we use expiry dates from certificates of analysis (COAs) provided by the sponsor/vendor. For critical reagents prepared in-house, we usually follow our standard operating procedure (SOP) based on the type of reagent, e.g., for an antibody-based critical reagent, we assign a 1 year expiry and retest annually.
(Q) How do you apply the correction factor, as you see >20% QC bias between using two different lots of reagents? In other words, will the correction factor be applied to assay modification or study data?
(A) The correction factor is usually used when bridging sample analysis kits, in which standards and buffers are included for standard calibrators and QCs preparation. From kit to kit, the buffer and standard material are different to a certain extent and the overall comparison in QCs will be greater than individual standard material lots. The correction factor will be applied to the study data, not the assay.
(Q) Can you speak on extending expiration dates via retesting?
(A) We perform one run with one set of standards and two sets of QCs (HQC, MQC and LQC) loaded to plates in duplicate. If the run passes, the expiration may be extended for a time equal to the original time interval.
(Q) What is the purpose of BIO-006 Change Control Procedure?
(A) BIO-006 Change Control Procedure SOP provides a procedure for managing document and equipment changes at Frontage Laboratories. It outlines the method of documenting and controlling changes to issued documents and equipment, as well as track changes.
(Q) What should the re-testing frequency for in-house conjugated reagents, e.g., biotinylated drug or digoxin drug, be?
(A) We usually retest once a year since the labelled reagents tend to become aggregated, leading to a higher signal over time. This change is more detrimental to ADA studies in which the raw data are evaluated for positiveness and titer of the ADA confirmed. We would rather re-label reagents than re-testing the regents.
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