Why should you not use a pipette with a broken tip?

Why should you not use a pipette with a broken tip?

Allowing the tip of the pipet to rise above the liquid in the container usually causes the liquid to be sucked into the pipet bulb. A broken or chipped pipet can reduce the amount of liquid held after transfer. This causes too much liquid to be delivered.

How do you use a micropipette?

Steps to follow when using a micropipette

  1. Select the volume.
  2. Set the tip.
  3. Press and hold the plunger at the first stop.
  4. Place the tip in the liquid.
  5. Slowly release the plunger.
  6. Pause for a second and then move the tip.
  7. Insert the tip into the delivery vessel.
  8. Press the plunger to the second stop.

What are the common errors done by technicians while handling 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.

What would happen if the pipette was held at an angle while pulling liquid up?

Holding the pipette at an angle as it is removed from the sample alters the volume aspirated. Touching the sides of the container can cause wicking and a loss of volume due to the effects of surface tension.

What should you not do when using a micropipette?

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.

Why should you avoid submerging the micropipette tip too deep in the liquid?

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.

How do you reverse pipetting?

How to Reverse Pipette

  1. Set the pipette to the desired volume.
  2. Depress the plunger completely – past the first stop to the second (blowout) stop.
  3. Immerse the tip in the liquid, and slowly release the plunger to full extension.
  4. Dispense by pressing to the first stop.
  5. A small volume of liquid will remain in the tip.

What happens if you push the plunger to the second stop before drawing up the liquid?

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.

What precautions should be taken while using pipettes?

Take Care of Your Pipette

  • Have Your Pipette Serviced Every 6–12 Months.
  • Check Your Pipette for Damage Daily.
  • Clean Your Pipette Each Day Before Use.
  • Store Your Pipette Vertically, Using a Pipette Holder.
  • Never Put Your Pipette on Its Side With Liquid in the Tip.
  • Use Well-Fitting Tips.

What are three important precautions in micropipette use?


  • Never adjust the volume beyond the range of the micropipette.
  • Never force the volume adjustor dial.
  • Do not drop the micropipette.
  • Always use a smooth motion when using the micropipette.
  • Always keep pipettes upright.
  • Never lay a pipette with liquid in the tip on the bench.

How can I improve my pipetting accuracy?

  1. Pre-wet the pipette tip. Aspirate and fully expel an amount of the liquid at least three times before aspirating for delivery.
  2. Examine the pipette tip for droplets.
  3. Pause consistently.
  4. Minimize handling of pipette and tip.
  5. Use the correct pipette tip.

How can you tell if a pipette is dirty?

One sure sign that glassware is dirty is the formation of water droplets on the inside wall of the glassware. If after cleaning with soap, water and a brush, water droplets form you probably did not clean the glassware well enough and should repeat the washing until no droplets form when rinsed with distilled water.

Why should you never pipette by mouth?

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.

What is the largest source of pipetting problems?

Human error is the largest source of pipetting problems, followed by liquids sticking to the tips, and loss of accuracy when working with viscous liquids (multi-option select question, chart depicts the percent of survey respondents who experienced these various pipetting errors).

What are the effects of temperature in pipetting?

The warming of the pipette tip causes the captive air to expand and push liquid from the tip. Less liquid is aspirated and subsequently dispensed, leading to a variation between the target and delivered volumes. The opposite is true when a technician pipettes cold liquids.

How are pipettes being calibrated?

The calibration of pipette is carried out by gravimetric method. When determining the volume of water, the accuracy of measurements is effected by ambient temperature, atmospheric pressure and relative humidity. These factors are usually combined to give the Z factor, used in calculation of volume of water.

Can the heat of your hand affect pipetting accuracy?

Hand warming effects When pipetting for long periods, heat from your hand can warm the air inside the pipette, caus- ing it to expand and leading to inaccurate results.

Does room airflow affect pipetting accuracy?

The most important factor in pipetting accuracy is the liquid temperature. The figure below shows the change in volume when the liquid has a different temperature than the pipette and air. If the temperature of the liquid, pipette and air is the same, the accuracy is not significantly affected.

Is reverse pipetting more accurate?

Reverse pipetting is more precise in dispensing small volumes of liquids containing proteins and biological solutions compared to forward pipetting, which is mostly used for aqueous solutions, such as buffers, diluted acids or alkalis.

What are air displacement pipettes used for?

An air displacement pipette is a common laboratory tool used to handle a measured volume of liquid between 1 µl to 1000 µl (1 ml). Due to its high accuracy, this laboratory tool is commonly used in standard pipetting applications.

What stop do you go to in order to pipette the correct volume?

The first stop is the stop that changes; it is the amount that you set the pipette to in the previous step, and it is shown by the first picture. The second stop, shown in the second picture, is an extra ‘push’ that it sometimes needed to remove all of the liquid from the tip.

How do I know what pipette to use?

As a rule of thumb, always choose the smallest pipette capable of handling the required volume. This is important because accuracy decreases when the set volume is close to the pipette’s minimum capacity. For example, if you dispense 50 µl using a 5,000 µl pipette, you will get rather poor results.

How accurate are micropipettes?

Micropipettes are designed to operate with accuracies within a few percent (generally <3%) of the intended value. The accuracy of a micropipette decreases somewhat when micropipettes are set to deliver volumes close to the lowest values in their range.

What are the different types of micropipettes?

Air displacement micropipettes

Pipette type Volumes (μL) Tip color
P20 2–20 yellow
P200 20–200 yellow
P1000 200–1,000 blue
P5000 1,000–5,000 white

What are the two types of pipettes?

What are the Different Types of Pipettes Used in Dentistry?

  • Disposable Pipette. The disposable pipette is the most basic version of this tool.
  • Graduated Pipette.
  • Single-Channel Pipette.
  • Multichannel Pipette.
  • Repeat Dispensing Pipette.

Which type of pipette is more accurate?

volumetric pipette

Where are micropipettes used?

Micropipettes are generally used in microbiology, chemistry and medical testing laboratories for the accurate and precise transfer of samples.

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