This second stopping point is used for the complete discharging of solutions from the plastic tip. Never go to the second stop when drawing liquid into the pipettor, as this will increase the volume taken up.

Never point a pipette up. This may cause liquid to run down into the pipette destroying it. When withdrawing liquids with the pipette, always release the plunger slowly. This prevents liquid from rushing into the end of the pipette and clogging it up.

Too much immersion will cause liquid to stick to the outside of the tip, and too little immersion will result in air bubbles. Minimize handling of the pipette and tip – The heat transferred from your hands to the pipette and/or the tips can affect delivery volumes.

5 Tips to Improve Your Pipetting Accuracy

1. Pre-rinse your new pipette tips before aspirating a sample for delivery.
2. Ensure the tips immersion depth is correct.
3. Ensure the micropipette is upright during pipetting.
4. Apply consistent plunger pressure and speed.
5. Good micropipette.

Pipetting is most accurate when the pipette is held vertically. Keep the angle less than 20° from vertical for best results.

volumetric pipette

volumetric pipet more accurate because its long size decreases error of misreading the meniscus and volumetric pipets are designed to measure specific volumes (such as 5ml). Also graduated cylinders are not calibrated during manufacture process.

A firm seal between tip and pipette is important, otherwise the amount of solution that you draw up will be inaccurate. If the tip falls off, throw it away. A sterile tip is necessary for experiments, otherwise contamination will ruin your result.

Never let the plunger snap up. This can cause air bubbles to fill the tip, destroying accuracy and may eventually lead to damage to the micropipette. Never the lay the micropipette down when liquid is in the tip. This may allow fluid to enter the pipette and ruin it.

Do not ever use your mouth to pull the liquid into a pipet. This is the most common method of becoming poisoned in a chemical laboratory or becoming infected in a clinical laboratory. Also, having the bulb attached to the pipet increases the risk of drawing the solution into the bulb. …

Replace the lid of the tip box to keep the remaining tips sterile. Avoid touching the tip (especially the thinner end), because the tips are sterile. Depress the plunger of the micropipette to the FIRST stop. than 20 ̊ from vertical for best results.

Why should you avoid submerging the micropipette tip too deep in the liquid? – We should avoid submerging the micropipette tip too deep in the liquid due to too much immersion will cause liquid stick to the outside of tip and more liquid will deliver than was desired.

He says that pushing to the second stop messes up the vacuum and causes you to draw in more liquid the next time you use it. If you don’t change tips, it’s better to leave a little liquid in the tip.

Immerse the tip to the proper depth during aspiration Too much immersion can cause samples to cling to the outside of the tip. Touching the container bottom with the tip may restrict aspiration.

When aspirating, two factors can influence the accuracy of your measurement — the aspiration angle and immersion depth. Prepare the micropipette by holding it in a nearly vertical position and depressing the plunger or push-button to the first stop position using your thumb.

When the operating button is pressed to the first stop, the piston expels the same volume of air as indicated on the volume setting. 3. After immersing the tip into the liquid, the operating button is released. This creates a partial vacuum and the specified volume of liquid is aspirated into the tip.

Before aspirating, immerse the tip adequately below the meniscus. Too little immersion, particularly with large volume pipettes, can lead to aspiration of air. Too much immersion can cause liquid to cling to the outside of the tip. Contacting the container bottom with the tip may restrict aspiration.

Many lab workers pipette for longer periods each day. Typical symptoms include pain in the thumb (De Quervain’s syndrome), forearm and elbow (tendonitis or tenosynovitis), trigger finger, finger pain (digital-nerve injury), and shoulder pain.

Best pipetting practices

• Pause after aspirating.
• Do not touch vessel wall during or after aspiration.
• Use consistent plunger speed and pressure.
• Minimize heat transfer from hands.
• Avoid tip wiping.
• Examine tip prior to dispensing.
• Use high-quality pipet tips.
• Use proper pipet size.

Filling the pipette using a Pi-pump Hold the pipette at the top and carefully insert it into the Pi-pump by pushing gently and rotating slightly. 2. Place the tip of the pipette in the solution. Use the thumbwheel to raise the level of liquid to above the graduation mark on the pipette.

Common pipetting errors include:

• Failure to Pre-Wet Pipette Tip.
• Disregarding Temperature.
• Tip Wiping.
• Choosing the Wrong Pipetting Mode.
• Working Too Quickly.
• Pipetting at an Angle.
• Using the Wrong Pipette Tips.

Many pipette types work by creating a partial vacuum above the liquid-holding chamber and selectively releasing this vacuum to draw up and dispense liquid. Measurement accuracy varies greatly depending on the instrument.

RNase

1. Rinse with a detergent solution.
2. Rinse well with distilled water.
3. Rinse in 95% ethanol.
4. Allow to dry.
5. Soak the parts in 3% hydrogen peroxide for 10 minutes.
6. Thoroughly rinse with distilled water.
7. Air dry as above.