Podcast
Questions and Answers
What is the purpose of zeroing the scale?
What is the purpose of zeroing the scale?
- To subtract the weight of the plastic boat and measure the weight of the substance (correct)
- To measure the weight of the plastic boat
- To calibrate the pipette
- To add the weight of the plastic boat to the weight of the substance
Why is it necessary to wipe down the pipette with ethanol?
Why is it necessary to wipe down the pipette with ethanol?
- To sterilize the pipette
- To clean the pipette
- To calibrate the pipette
- To kill any contaminants (correct)
What is the purpose of recording multiple readings of the same volume?
What is the purpose of recording multiple readings of the same volume?
- To get a single accurate reading
- To discard the outliers and keep the rest
- To average them all together and get a more accurate result (correct)
- To repeat the experiment multiple times
What is the purpose of pre-rinsing the pipette tip?
What is the purpose of pre-rinsing the pipette tip?
Why is it important to immerse the pipette tip completely during aspiration?
Why is it important to immerse the pipette tip completely during aspiration?
What should you do after aspirating the same volume of water?
What should you do after aspirating the same volume of water?
How many times should the pipette tip be pre-rinsed?
How many times should the pipette tip be pre-rinsed?
Why is it important to wait until the number has stabilized on the balance?
Why is it important to wait until the number has stabilized on the balance?
What is the purpose of pre-rinsing the tip?
What is the purpose of pre-rinsing the tip?
What should be done after aspirating the calibration volume?
What should be done after aspirating the calibration volume?
What is the variable Z based on?
What is the variable Z based on?
What is the purpose of testing both the smallest and largest volumes of the pipette?
What is the purpose of testing both the smallest and largest volumes of the pipette?
Why should you keep the tip on the pipette?
Why should you keep the tip on the pipette?
What should be used to wipe down the pipette?
What should be used to wipe down the pipette?
What should you do with the tip after dispensing the liquid?
What should you do with the tip after dispensing the liquid?
What is the formula for calculating the volume dispensed by the pipette?
What is the formula for calculating the volume dispensed by the pipette?
What is the purpose of averaging the replicate weights together?
What is the purpose of averaging the replicate weights together?
What is the formula to calculate the accuracy of the pipette?
What is the formula to calculate the accuracy of the pipette?
What is the acceptable range for the accuracy of the pipette?
What is the acceptable range for the accuracy of the pipette?
What is the purpose of using the Z value in the calculation?
What is the purpose of using the Z value in the calculation?
How many replicates are recommended to ensure accurate results?
How many replicates are recommended to ensure accurate results?
What is the formula to calculate the calculated volume?
What is the formula to calculate the calculated volume?
What is the purpose of calculating the calculated volume?
What is the purpose of calculating the calculated volume?
What is the unit of the Z value?
What is the unit of the Z value?
What is the department involved in preparing working standard solutions from stock standards?
What is the department involved in preparing working standard solutions from stock standards?
What year of study is this practical guide intended for?
What year of study is this practical guide intended for?
What is the title of the practical guide?
What is the title of the practical guide?
What is the purpose of Practical No. 9?
What is the purpose of Practical No. 9?
What is the page number of Practical No. 9?
What is the page number of Practical No. 9?
What is the title of Practical No. 10?
What is the title of Practical No. 10?
What should you do with a pipette that does not pass the calibration test?
What should you do with a pipette that does not pass the calibration test?
Who should you contact for servicing if your pipette needs to be calibrated?
Who should you contact for servicing if your pipette needs to be calibrated?
What is the purpose of the comment section in the practical guide?
What is the purpose of the comment section in the practical guide?
What is the purpose of the date section in the practical guide?
What is the purpose of the date section in the practical guide?
Why is it important to have your pipette calibrated?
Why is it important to have your pipette calibrated?
What happens if you try to fix a pipette's calibration issue yourself?
What happens if you try to fix a pipette's calibration issue yourself?
Why are pipettes considered delicate?
Why are pipettes considered delicate?
Can some companies come to your lab to calibrate your pipettes?
Can some companies come to your lab to calibrate your pipettes?
What is the consequence of using a pipette that has not been properly calibrated?
What is the consequence of using a pipette that has not been properly calibrated?
Why is it important to stop using a pipette that does not pass the calibration test?
Why is it important to stop using a pipette that does not pass the calibration test?
What is the purpose of calibrating a pipette?
What is the purpose of calibrating a pipette?
Who typically performs pipette calibration services?
Who typically performs pipette calibration services?
Study Notes
Pipette Calibration
Preparing the Balance
- Use a balance with doors (isolated chamber) or place the weigh boat directly on the balance.
- Close the doors (if using a chamber balance) and zero the scale by pressing the "Zero" or "Tare" button.
Preparing the Pipette
- Wipe down the pipette with ethanol to kill contaminants.
- Ensure the pipette tip is not clogged.
- Place the appropriate tip on the end and set the desired volume to test.
Calibrating the Pipette
- Test both the smallest and largest volumes the pipette can dispense.
- Pre-rinse the tip by aspirating and dispensing distilled water three times.
- Aspirate the calibration volume by immersing the tip 2 mm in distilled water and releasing the button.
- Dispense the liquid into the weigh boat on the scale.
Recording and Repeating the Process
- Record the weight on the balance after the liquid has been dispensed.
- Repeat the process at least 10 times to take multiple readings of the same volume.
- Average the replicates together by adding the values and dividing by the total number of trials.
Calculating the Results
Calculating the Volume
- Use the formula: V = w * Z, where V is the calculated volume, w is the weight of water, and Z is the conversion factor based on the density of water.
Averaging the Replicates
- Add up the weights recorded for each trial and divide by the total number of trials.
- For example, if the weights recorded are 9.89, 10.01, 10.02, ..., the average would be (9.89 + 10.01 + 10.02 + ...)/10 = 9.984.
Calculating the Accuracy
- Use the formula: A = 100 x Vavg/V0, where A is the accuracy of the pipette, Vavg is the average calculated volume, and V0 is the value set on the pipette.
- For example, if Vavg = 10.019 and V0 = 10, then A = 100 x 10.019/10 = 100.19%.
What to Do if the Pipette Fails Calibration
- If the pipette does not pass the calibration test, stop using it immediately and send it for proper servicing.
- Contact the company that makes the pipette for servicing.
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Description
Learn how to properly calibrate a balance and pipette for accurate measurements in a laboratory setting. This quiz covers the steps to zero a balance and prepare a pipette for calibration.
