What is a common challenge when performing dilutions with very small final volumes?

• A. Increased pipetting error and decreased accuracy
• B. No challenge; it's more accurate
• C. It speeds up work
• D. It eliminates need for diluent

Answer: (A)

When diluting to very small final volumes, the precision of the liquid handling becomes the limiting factor. The amount a pipette dispenses carries a fixed absolute error, so as the target volume gets smaller, that same error represents a larger fraction of the final volume, causing the dilution to be less accurate. Tiny transfers are also more affected by issues like dead space in the tip, adsorption to surfaces, and evaporation, all of which introduce additional variability. Because of these factors, the biggest challenge is increased pipetting error and decreased accuracy. To improve reliability, scientists often perform dilutions at larger volumes and scale down, or use techniques and equipment designed for high-precision small-volume transfers, along with careful technique and calibration.