1. Precision Pipetting and Laboratory Best Practices

1. Front: Lab coat cuff adjustment and safety

Back: Cuffs must be adjusted to the wrist using buttons or clicks to prevent dragging sleeves into samples (contamination) or snagging equipment.

2. Front: Rationale for lab-exclusive, closed footwear

Back: Dedicated footwear prevents external dust from entering sensitive nanometric-scale labs. It must be closed to protect against chemical spills like sulfuric acid.

3. Front: Glove material selection: Nitrile vs. Latex

Back: Nitrile is preferred for long sessions as it generates less tension on the knuckles. Latex is highly elastic and can cause a painful "burning" sensation during repetitive pipetting.

4. Front: Risks of contact lenses and safety glasses

Back: Lenses are porous and absorb toxic vapors, making eye rinsing difficult. Safety glasses are mandatory to prevent permanent ocular damage.

5. Front: Accuracy principle in pipette selection

Back: Accuracy is maximized when the target volume is near the pipette's nominal (upper) limit. For 150 µl, a P200 is more precise than a P1000.

6. Front: Minimum volume safety limit for pipetting

Back: Pipetting below 1 µl is discouraged due to extreme variability. Liquid adhering to the tip's exterior can exceed the volume inside.

7. Front: Mechanical volume adjustment technique

Back: Always use the volume adjustment dial instead of the plunger button. Using the plunger can break the internal metal rod and decalibrate the instrument.

8. Front: Consequences of exceeding pipette limits

Back: Forcing a pipette beyond its range (e.g., a P20 to 22 µl) damages the mechanical piston. This introduces errors ranging from 10% to 50%.

9. Front: General rule for plunger stops in daily use

Back: Use only the first stop if the tip appears clean. Repeatedly forcing the second stop increases physical strain and error.

10. Front: Second plunger stop: Usage and Carpal Tunnel risk

Back: It is used for large volumes (P1000) to clear residual liquid. Overuse in repetitive tasks can lead to carpal tunnel syndrome and surgery.

11. Front: Positive displacement pipettes (Mechanism)

Back: These use an internal piston in direct contact with the liquid, eliminating the air cushion. Ideal for highly volatile or viscous samples.

12. Front: Protocol for hazardous samples Radioactive/Biological)

Back: Use pipettes that are easy to clean (without external ejectors) and keep them exclusive for these tasks. Never mix them with general lab work.

13. Front: Protocol for corrosive samples (Acids/Bases/Salts)

Back: Avoid pipettes with metal parts, such as external metal ejectors, which oxidize easily. Use plastic

14. Front: Risks of gloves near a Bunsen burner

Back: Gloves are highly flammable and melt onto the skin, complicating burn treatment. Hand washing and aseptic technique are safer.

15. Front: Impact of fatigue on lab accuracy

Back: Fatigue causes avoidable errors. Stepping away from a "stuck" experiment often reveals simple mistakes overlooked during exhaustion.

16. Front: Lab zoning for Molecular Biology

Back: Physical separation of RNA, DNA, Protein, and Electrophoresis areas is vital to prevent cross

17. Front: RNA sensitivity and RNase management

Back: RNA degrades easily due to ubiquitous RNases on hands. Use specialized sprays and exclusive equipment for all RNA work.

18. Front: Purpose of RNase

decontaminating sprays

19. Front: Protection for sensitive machinery (qPCR/Sequencers)

Back: Protect equipment with UPS systems against power surges and maintain them in temperature

20. Front: Advantage of removing the pipette ejector

Back: It allows the pipette to enter 15 ml Falcon tubes without the shaft touching the walls, reducing contamination.

21. Front: Maintenance of metal ejector shafts

Back: Regularly clean the metal ejector, as corrosive vapors can cause oxidation and dirt buildup.

22. Front: Gravimetric check for pipette calibration

Back: Weigh water on a precision balance

20 µl of water must weigh exactly 20 mg at standard density.

23. Front: Precise selection for 32 µl measurement

Back: Use a P20 at its upper limit twice (20+12) or split into 16+16 to ensure higher precision than a P100 at its lower range.

24. Front: Splitting large volumes (e.g., 350 µl) for accuracy

Back: Splitting (e.g., 200+150 with a P200) is more reproducible than using a P1000 at its lower, less accurate range.

25. Front: P2 vs. P200 graduation for 0.5 µl

Back: A P2 is specifically designed for 0.5 µl accuracy, whereas the 0.5 mark on a P200 is just a vague line.

26. Front: Filter tips vs. Aerosol contamination

Back: Filter tips prevent aerosols from entering the pipette mechanism, protecting the next sample from cross

27. Front: Modified tip method for high viscosity

Back: Cutting the tip's end increases the orifice, allowing thick fluids like glycerol to flow without clogging.

28. Front: Reverse Pipetting logic (Procedure)

Back: Aspirate at the second stop and dispense at the first. This uses extra force to pull viscous fluids into the tip.

29. Front: Volatile samples and air displacement

Back: Volatiles (Ethanol/Formaldehyde) evaporate in the air cushion of standard pipettes, leading to volume loss.

30. Front: Inter

worker variability in experiments

31. Front: Precision in repetitive pipetting (Targeting)

Back: In 96

32. Front: Optimal aspiration depth

Back: Position the tip in the center of the liquid. Too high sucks in air

too low causes wall interference.

33. Front: Dispensing angle and wall touch

Back: Hold the tube at an angle and dispense against the wall to ensure the entire volume is released.

34. Front: Cleaning external droplets protocol

Back: Wipe external droplets against the wall of the source container before transfer to avoid adding extra volume.

35. Front: Circular wrist motion for tip adjustment

Back: Instead of striking the box, use a circular wrist motion to secure an airtight seal without damaging the pipette.

36. Front: Multichannel lateral adjustment

Back: Press down and move the pipette laterally toward both ends to seal all tips simultaneously.

37. Front: Advantages of pre

rinsing (pre

38. Front: Error %: Leaking or ill

fitted tips

39. Front: Error %: Reusing or autoclaving tips

Back: Reusing tips, even if cleaned, introduces a cumulative error of approximately 4%.

40. Front: Error %: Bent or deformed tips

Back: Damaged tip orifices interfere with vacuum measurement, resulting in errors over 10%.

41. Front: Error %: Failure to touch the container wall

Back: Leaving a droplet on the tip instead of touching the wall adds a 3% error to the measurement.

42. Front: Error %: Piston or Calibration failure

Back: Mechanical leaks in the piston or poor calibration cause massive errors between 10% and 50%.

43. Front: PCR tube lids: Flat vs. Domed Back: Flat lids are preferred for better contact and uniform heating with the thermal cycler’s heated lid.

44. Front: Use of 5 ml tubes for intermediate volumes

Back: They provide a cleaner alternative for 2–5 ml volumes, preventing contamination from Falcon tube walls.

45. Front: Material affinity: Plastic

binding molecules

specialized low

binding tubes must be used.

46. Front: pH adjustment: The 80

90% rule

47. Front: Correcting overweighed solute in solution prep

Back: Recalculate the required final volume using the mass weighed: V final =mass weighed/(MW×Target Molarity), then add the extra solvent needed.