Question 1 of 6 Fundamentals Concept
What can make a liquid-handling workflow unreliable?
Short answer
An automated pipetting robot can perform a protocol exactly as written and still produce biased or inconsistent transfers. Liquid properties, labware geometry, calibration, tip choice, contamination and identity errors all matter.
Why
Automation removes some manual variation, not experimental uncertainty. Aspirating a viscous reagent with settings tuned for water may cause under-delivery. Other common sources include wetting behaviour, bubbles, evaporation at plate edges, an incorrect well depth, unsuitable tips, misaligned deck labware and different channels behaving differently.
Separate software command execution from observed liquid delivery. Qualify intended volume ranges and representative liquids, verify trueness and precision, test edge wells and carryover, and use appropriate positive, negative and blank controls. Confirm barcode mapping before and after transfers.
Inspect logs for skipped commands and interventions rather than assuming a completed run means an accurate one. A method that passes with water may fail with glycerol-containing buffers. Apply risk-based requalification when equipment, protocol or software settings change.
Common mistakes
- Equating a completed robot run with verified sample identity and accurate volumes
The interviewer might ask next
Which measurements would detect a channel-specific bias that routine positive controls missed?