Pipettes are commonly used liquid handling tools in laboratories and need to be calibrated regularly to ensure their accuracy and consistency. Here's a detailed explanation of the pipette calibration steps:
1. Prepare tools and materials.
The following tools and materials are required before performing pipette calibration:
1.Pipettes.
2.Weight.
3.Laboratory balances.
4.Sterile water or saline.
5.Marker.
6.Paper towels or clean cloths.
2. Calibration steps.
1.Visual inspection.
First, check the appearance of the pipette to make sure there is no visible damage or wear. At the same time, check whether the tip and the barrel are tightly connected and there is no loosening.
2.Prepare weights.
Depending on the capacity of the pipette, select the weight of the appropriate mass. For example, if the pipette has a volume of 1000 l, choose a weight with a mass of 1000 l. If you don't have a weight of the corresponding quality, you can use a combination of several small weights.
3.Calibrate the tips.
Remove the tip of the pipette and wipe it clean with a paper towel or a clean cloth. Then, place the tip on the balance and use a marker to record the weight in g. This mass value will be used as a reference value for calibration.
4.Calibrate the capacity.
Remove the tip of the pipette and insert the barrel vertically into the holder of the balance to ensure the balance of the pipette. Then, attach the tip back to the pipette and place the pipette on the balance. Record the mass of the pipette on the balance (in g). This mass value will be used as a reference value for calibration.
5.Calculation error.
The error is calculated according to the following formula: Error = (Actual Mass - Reference Value) 100% of the Reference Value. If the error is greater than 1%, it needs to be adjusted. Otherwise, you can continue to use it.
6.Adjust the error.
If the error is greater than 1%, it needs to be adjusted. First, place the pipette on the balance and record the actual mass with a marker. Then, adjust the quality of the pipette according to the error value. For example, if the error is +15%, you need to increase the mass of the pipette by 15% weight mass. After adjustment, the error value is measured again until the error is within 1%.
7.Repeat calibration.
In order to ensure the accuracy of the calibration, it is recommended to perform multiple calibrations of the same pipette. Each calibration is spaced apart for a period of time (e.g., 1 month) to better detect the stability of the pipette. If the results are similar and within the margin of error, the pipette's performance is stable and reliable. Otherwise, it may be necessary to replace the pipette with a new one.
In conclusion, regular calibration of the pipette guarantees its accuracy and consistency, thus ensuring the reliability of the experimental results. When performing calibration, you need to follow the above steps and take care to keep the laboratory environment clean and dry to avoid factors that can affect the calibration results.