From assay development to assay transfer (Part 3): keeping track of the details for effective documentation
Mar 28, 2016
When automating an assay and/or transferring that assay to another lab, little details can make big differences, which is why effective documentation, including a clear and detailed standard operating procedure (SOP), is critical. But what needs to be included in this SOP? And how do you decide what goes into a transfer protocol?
In this third and final article in our three-part series on assay transfer, we discuss factors to consider for creating effective documentation. Additional tips for facilitating assay transfer can be found in Lab Report 7: Facilitating Assay Transfer by Controlling Liquid Handling Variables.
Set up a template
As we’ve written before, details are important when automating or transferring an assay. Environmental conditions, the mechanics of how you hand-pipette during the manual assay, the automated liquid handler make and model, the liquid class and other settings, the type of tips used, the type of plates used, the tip size-to-volume transferred…all of these and more can affect assay performance and the success of assay transfer. So how do you quickly and succinctly capture what’s important?
Dr. Nathaniel Hentz of the Biomanufacturing Training and Education Center at North Carolina State University, recommends setting up a template for your SOP that records all the information necessary for the assay, from the materials used and their handling and storage to the specific equipment and settings. Being as specific as possible with your documentation can help the receiving lab reproduce the results and obtain the same assay performance.
For example, pipette tips differ in design and materials, even though they may fit the same instrument. If the receiving lab uses tips that are different from the originating lab, they may not see the same level of performance due to variations such as fit between the seal with the pipetting head, differences in the interactions between the sample and the plastic of the tip, and so on. Similar issues can also affect microplates. By documenting the specifics, you’re setting the foundation for successful transfer.
Document performance metrics
In addition to recording the materials, reagents, and equipment settings, documenting the expected assay performance metrics is also critical. We recommend indicating not only the expected accuracy, precision and trueness for the assay, but also the number of samples used to obtain those measurements. This simplifies the statistical analysis and comparison of results between labs. And if the performance metrics don’t match up, a well-documented SOP can reduce time spent troubleshooting by either providing points of differences between the two labs, or ruling out factors that could be the issue.
To summarize—map out the workflow to be sure nothing is missed
Because each assay is different, it’s difficult to put together a single comprehensive checklist that anyone can use. But we can recommend being as specific as possible in what you document, and provide a framework that can get you on your way:
- Start with your samples and reagents and document how you handle them—storage temperature and conditions, handling prior to assay, when they were made, etc.
- Document all the equipment that you use—manufacturer and model number, settings, and any consumables that are also used.
- List every step of the process, making sure to include all equipment, reagents, and consumables and how samples are handled. For example, are they left covered or uncovered? How are they covered?
- For some assays, keeping track of the environment is also critical. For example, temperature, humidity, and even barometric pressure can affect sample evaporation rate. If the same assay is run in two different test labs where these environmental parameters differ, the results can vary significantly.
- Specify performance metrics for the assay—so the receiving lab can know what to expect.
Good luck with your assay transfer – and don’t neglect solid documentation to help make this a success. Additional resources for assay transfer can be found below.
- Blog: From assay development to assay transfer (Part 1): it’s the little things that matter
- Blog: From assay development to assay transfer (Part 2): making sure everything measures up
- Publication: Considerations for the design and reporting of enzyme assays in high-throughput screening applications, covers the design of high-throughput enzymatic assays, providing information that can also be used to guide assay transfer. Perspectives in Science. 2014 May; 1:56-73.
- Publication: The transfer of analytical procedures. Journal of Pharmaceutical and Biomedical Analysis. 2013 Nov; 85:262-76. PMID: 23978903
- Book: The Assay Guidance Manual is freely available through NCBI. While the original publication date of the collection is 2004, many of the articles have been updated more recently.
- Lab Report 7: Facilitating Assay Transfer by Controlling Liquid Handling Variables
About the Expert
Tanya Knaide is a scientist with over 10 years of experience in leading new product development projects, product launch campaigns and uncovering customer needs to develop innovative new products and services to satisfy them. As Product Manager at Artel, Tanya has led cross-functional and inter-organizational teams that span across R&D, engineering and marketing and ensured that development and marketing projects deliver benefits to the customer in a timely manner.