Assay development and more: When you want to verify volume transfer into a non-MVS plate
At the end of our September 2016 Webinar on “Troubleshooting Liquid Handler Methods,” a viewer asked the following assay validation question:
Using the Artel MVS, do you have any tips with regards to pipetting into one plate type and then reading in another and how to minimize loss of material, specifically when transferring from three or more 384-well plates?
There are really two parts to this question:
- How do you verify volume transfer when the receiving plates are not MVS-specific?
- How can you measure the amount of residual material left in the source plate after a transfer, so that you know you’ve minimized the amount of sample left behind?
We’ve addressed these issues in two Application Notes, summarized here (and downloadable from the Artel website; links provided below in the Additional Resources list).
Verifying volume transfer when the receiving plate is not MVS-specific
It’s not uncommon for a lab to want to verify volume transfer into a specific type of plate. Because plate type can affect volume transfer, labs that need a high degree of confidence in their volume verification will typically dispense into the same plate type used in a live assay.
In the field test application of this process [using a 384-channel Biomek FX], the users of the Biomek insisted that the target volume be dispensed into the v-bottom plate (assay plate). They did not want to dispense the target volume directly into the MVS-compatible plate because “…it was not the same geometry and the automated methods could act differently…the tip depth and tip touches might not perform the same in the different plate and then I won’t know if the source of error is the plate or my method or both.”1
What, then, can an automated liquid handler user do if the receiving plate is not compatible with the MVS? In this situation, you need to add a second transfer step to move the sample from the original receiving plate into an MVS-compatible plate. In order to optimize the efficiency of this extra transfer, we recommend a series of Diluent additions and transfers as summarized in Figure 1.
Figure 1. Schematic flow diagram for testing target volumes in specialized plates or small liquid containers
The full protocol and proof-of-concept data for this method can be found in the application note, “Volume Verification Using Any Microtiter Plate or Small Volume Container Such as a Tube or Vial.”
While generally useful, there are some considerations and limitations to bear in mind, which are also discussed in the application note. One that I’d specifically like to mention here is what to do if your transfer volume is too large to accommodate enough Diluent additions and transfers. In this situation, we recommend that you first transfer the target volume to the MVS-compatible plate type that holds the largest working volume, and then transfer the remaining target volume with Diluent steps. You can also check how much residual volume is left in a plate after aspiration using the MVS, to be sure that you’ve maximized transfer efficiency.
Measuring residual sample volume after aspiration
You can use a similar Diluent-based transfer method to measure the amount of residual sample left in a non-MVS plate, which is summarized in Figure 2. The full details of the protocols and the simpler method that can be used for MVS-compatible plates are covered in the application note, “Measuring Residual Volumes Remaining in a Plate After Sample Aspiration.”
Figure 2. Overview of the approach employed to use the MVS for measuring residual volumes in a non-MVS plate, such as a deep well plate.
Conclusion
If your assay calls for transfer into specialized plates, you can use the MVS to verify volume transfer with high confidence. The benefits of this approach – reliable, reproducible assay data – will be worth the effort.
Additional Resources
- Application Note: Volume Verification Using Any Microtiter Plate or Small Volume Container Such as a Tube or Vial
- Application Note: Measuring Residual Volumes Remaining in a Plate After Sample Aspiration
References
1. Keith J. Albert. Volume Verification Using Any Microtiter Plate or Small Volume Container Such as a Tube or Vial. Application Note 12A5553A (2007).
About the Author
Keith Albert
Keith is an expert in liquid handling performance management, providing customized services across a wide range of platforms, applications, liquid volumes, and liquid classes. As Senior Applications Specialist, Keith combines his extensive knowledge and experience with rigorous science in his work in liquid handling system performance research, customer education, and assay/method validation.
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