Is it really necessary to worry about both liquid handling precision and accuracy during assay development?

assay-developmentDuring assay development it’s vital to not only optimize with respect to biological relevance, robustness and signal window, but also to consider what effects liquid handling variability has on that assay. Oftentimes, precision is used as the primary quality indicator for liquid handlers. Precision is easy to measure, and it highlights gross failures within a liquid delivery step. However, it has been demonstrated that accuracy also impacts assays, especially as it relates to chemical potency. This issue translates to three very important concepts in drug discovery.

  • First, lower potency compounds may simply be missed due to predetermined cutoff criteria. This scenario can lead to missing important chemical scaffolds.
  • Second, the assay loses resolution for high-potency compounds that have similar IC50s. Loss in discriminating power can allow incorrect compound scaffolds to be chosen for further development.
  • A third important factor impacts assay transfer between labs, different liquid handlers, replacement liquid handlers, or during transitions from assay development through candidate selection. In these cases, liquid handlers that are not properly calibrated, especially with respect to accuracy, make assay transfer unnecessarily difficult. By ensuring that all liquid handlers are behaving identically, assay transfer time can be minimized.

Also, by studying the liquid handlers in the context of a particular assay, liquid handlers and reagents can be paired. For example, a reagent that is particularly sensitive to variability (such as an enzyme) should be paired with the best-performing liquid handler. Alternatively, the poorest-performing liquid handler should be used to dispense the least sensitive reagent. This approach can be especially true for automation systems with multiple liquid handlers that dispense different reagents. This ultimately reduces assay variability and improves data integrity.

About the expert

Nathaniel Hentz, PhD

Nat-HentzDr. Nathaniel Hentz is the Vice President at Artel.  Prior to joining Artel, Dr. Hentz served as the Associate Director of the BTEC Analytical Lab at North Carolina State University and Senior Research Investigator at Bristol-Myers Squibb in Wallingford, CT where his team supported the fully automated screening systems within the Lead Discovery group.

Before his time at BMS, Dr. Hentz worked at Eli Lilly RTP Laboratories in North Carolina. During his tenure at Lilly RTP, Dr. Hentz was responsible for Tier 1 ADMET screening in 2004 and led the New Technologies group.

Dr. Hentz received his PhD in analytical chemistry from the University of Kentucky in 1996 and joined Lilly as a postdoctoral scientist the same year.