What is the standard technique for pipetting aqueous solutions?

• A. Forward mode
• B. Reverse mode
• C. Both forward and reverse
• D. None of the above

Answer: (A)

Forward mode is the standard technique for pipetting aqueous solutions because it provides a straightforward, repeatable path from aspiration to dispensation. You load the tip by aspirating the exact volume, then dispense by moving the plunger to the first stop, which delivers the intended amount reliably. Aqueous liquids are low in viscosity and don’t tend to form bubbles or cling to the tip, so this method yields high accuracy and precision and aligns with typical pipette calibration. Reverse mode is advantageous for viscous, foaming, or volatile liquids, where overcoming retention in the tip is more challenging, but for standard aqueous solutions forward mode is the go-to approach.