Instruction 1

Exercise 1: Preparation of a Colored Saturated Sucrose Solution

• Prepare a 1.5 ml test tube,
• Pipette 405 µl of sucrose solution into the tube,
• Pipette 95 µl of purple dye onto the surface,
• Observe phase boundaries,
• Mix by pipetting and vortexing,
• Centrifuge in a benchtop microcentrifuge,
• Divide into two equal tubes,
• Note observations.

Exercise 2: Adding Small Volumes

• Label a 1.5 ml tube,
• Add 200 µl of sucrose solution,
• Add 3 µl of green dye,
• Add 3 µl of SDS detergent,
• Mix.
• Describe the procedure for adding small volumes using a pipette.

Exercise 3: Full Volume Transfer

• Label a 1.5 ml tube,
• Add 400 µl of sucrose, 10 µl of dye, and 10 µl of SDS detergent,
• Mix,
• Transfer solution to a 1.5 ml tube already containing 5 µl of dye,
• Mix,
• Observe and note if there's a risk of foaming.

Exercise 4: Performing a Serial 1:1 Dilution

• Add 30 µl of sucrose solution to each of 8 tubes,
• Add 30 µl of dye to the first tube,
• Transfer 30 µl to the next tube, repeating until all tubes are filled,
• Note the dilution level in each tube (1:1 dilution),
• Add 2 µl of dye to each tube,
• Specify the method for accurate dilutions (slow, controlled pipetting, consistent pressure).

Exercise 5: Centrifugation of Suspensions

• Prepare a 1.5 ml tube containing 300 µl of suspension,
• Add 50 µl of prepared solution,
• Centrifuge at 12,000 xg for 5 minutes,
• Pipette the liquid without disturbing the sediment,
• Suspend sediment in 150 µl of solution.

Basic Principles of Working with an Electronic Analytical Balance

• Analytical balances are precise instruments requiring specific handling & conditions,
• Place on a stable, level surface,
• Turn the balance on,
• Use dry, clean containers for accurate measurements,
• Close the door while weighing to avoid disturbance,
• Perform operations smoothly to avoid destabilization,
• Clean after usage and turn off.

Exercise 6: Weighing

• Weigh a 1.5 ml tube on an electronic analytical balance, record the measurement,
• Add 500 µl + 50 µl + 5 µl of water to the tube,
• Weigh again,
• Record results and conclusions,
• Attempt volume estimation using a 1000µl pipette.

Automatic Pipettes

• Automatic pipettes are used for quick measurement of small volumes (typically under 1 ml),
• Mechanism includes a piston, spring, handle, regulator, replaceable tip,
• Teflon or polyethylene tips are commonly used,
• Regulator precisely controls piston movement, regulating volume,
• Adjustment range is color-coded,
• Some models have automatic tip removal,
• Color-coded set points: Blue (100-1000 µl), Yellow (10-100 µl), Red (0.5-10 µl).

Pipetting Techniques

• Wetting the tip: Rinse the tip with the liquid being measured, crucial for viscous liquids.
• Holding the pipette: Hold upright, limiting angle to 20 degrees; avoid touching container walls.
• Immersion depth: Adjust immersion depth based on volume: large-volume pipettes (1-5 ml) ~5-6 mm, smaller volume pipettes ~2-3 mm.
• Operation: Use slow, even pressure when drawing/dispensing to avoid air bubbles.
• Choosing the correct pipette: Select with a volume slightly larger than desired for accuracy.