1. Two points should be noted when pipetting volatile samples.
a. Be sure to rinse twice before pipetting.
b. Drain the liquid as soon as possible after aspiration is completed.
2. Pipetting high viscosity samples
Use the reverse pipetting mode: press the aspiration/discharge button to the second position (second stop) when aspirating and to the first position (first stop) when discharging. Also, a dwell time of 3-5 seconds is required for both suction and discharge.
3. Pipetting high density/low density samples
The accuracy values of the pipette are based on transferring pure water. If the density of the sample differs significantly from the density of the water, then the accuracy will be correspondingly much worse. Therefore, it is necessary to find out the density of the sample before pipetting, and then adjust the range to the product of the volume of the sample to be transferred and the density.
For example, if the density of a sample is 1.2 g/cm3 and you need to transfer 300 ul, you should set the range to 360 ul. This is only a rough adjustment method, but a strict adjustment method requires the use of a gauge or balance as an auxiliary tool for accurate calculations.
4. Removing high and low temperature samples
Three points need to be noted when pipetting high/low temperature samples.
Firstly, never wet the pipette tips before pipetting.
Secondly, a new pipette tip should be used for each pipette.
Thirdly, aspirate and drain as quickly as possible.
Tips for pipette use
1. Use the right pipette tip: To ensure better accuracy and precision, it is recommended that the pipetting volume is within 35% to 100% of the range of the pipette tip.
2. Pipette tip installation: With most brands of pipettes, especially multichannel pipettes, fitting the tips is not an easy task: to achieve a good seal, the pipette sleeve handle needs to be inserted into the tip and then tightened by turning it left and right or rocking it back and forth. Some people also use the pipette to tighten the tips by repeatedly hitting them, but this can lead to distortion of the tips and affect accuracy, or in severe cases damage the pipette, so it should be avoided.
3. Tip immersion angle and depth: The tip immersion angle should be kept within a 20 degree tilt and should be kept upright; the tip immersion depth is recommended as follows: Pipette size Tip immersion depth 2 µL and 10 µL 1 mm 20 uL and 100 uL 2-3 mm 200 uL and 1000 uL 3-6 mm 5000 µL and 10 mL 6-10 mm
4. Tip rinsing: For normal temperature samples, tip rinsing helps to improve accuracy; however, for high or low temperature samples, tip rinsing may reduce accuracy and users should take special care.
5. Pipetting speed: Pipetting should be carried out at a smooth and appropriate speed; too fast an aspiration speed may result in the sample entering the sleeve, causing damage to the piston and seal and cross-contamination of the sample.
6. Recommendations for pipette use
1) Maintain a correct posture when pipetting; do not hold the pipette tightly at all times, use a pipette with finger hooks to help relieve hand fatigue; change hands frequently if possible.
2) Check the seal of the pipette regularly and replace the seal if it is found to be deteriorating or leaking.
3) Calibrate the pipette 1-2 times a year (depending on frequency of use).
4) For most pipettes, the piston should be lubricated before and after use to maintain the seal; for regular range pipettes, the seal is also ideal without lubricant.
Post time: Jun-03-2019