Manual single-channel adjustable pipette use and precautions
Pipette use and maintenance procedures
1. Purpose: To ensure the accuracy of pipetting. Ensure the accuracy and accuracy of pipetting.
Second, the principle: suitable for accurate sampling and transfer of liquids. Adopt the principle of air replacement, and use a detachable disposable nozzle to transfer liquid. The pipette is composed of positioning parts, capacity adjustment indication part, ejector device, piston sleeve and liquid suction nozzle.
3. Main operating regulations
1. Set the volume value: when adjusting the knob of the liquid intake, each time <1 turn, do not use too much force, and pay attention to the value displayed by the counter not to exceed its adjustable range.
2. Aspirate and dispense: First select a suitable nozzle to place on the pipette sleeve. Slightly twist the suction head so that there is no air gap between it and the sleeve. Press to the first gear, enter the liquid surface 2-4 mm vertically, slowly release the control button, and draw slowly and evenly when drawing liquid. Avoid liquid splashing on the pipette head and reduced suction volume.
2.1 Suction and discharge (replace the suction nozzle when changing to a different liquid)
2.1.1 Aspiration: Press the button to the first stop point; hold the pipette vertically to immerse the suction nozzle in the liquid sample. The immersion liquid depth depends on the model: 100 mL and 1000 mL 2-4 mm. Release the button steadily, aspirate the sample, wait for one second after the pipette is full of liquid, then lift the nozzle away from the liquid surface, adhere to the wall and stay for 2-3 seconds, so that the droplet outside the tip of the tube slides down.
2.2.2 Dispensing: Stick the suction nozzle to the inner wall of the container and keep it inclined at 10-40 degrees. Press the button steadily to the first stop point to drain the liquid, wait 1-2 seconds and press the button to the second stop point to drain the remaining liquid. Hold the button for 1-2 seconds, lift the pipette, and release the button. Press the nozzle ejector to remove the nozzle.
2.2.3 Nozzle cleaning. After use, put it in a beaker, add the washing solution, sonicate for 2 minutes, rinse with tap water, pure water, ethanol or methanol, and put it in a special box.
4. Dense and viscous liquid:
a) For liquids with a density lower than water, you can compensate by adjusting the reading of the volume meter below the required value. For example: use a pipette to transfer 10 mL of serum. First adjust the reading to 10 mL, and measure it gravimetrically after aspiration.
b) If the measured volume is 9.5 mL, that is, the deviation is 0.5 mL, then adjust the reading to 10.5 mL and repeat once. If the second time is still not accurate enough, adjust according to the deviation.
c) When discharging dense or viscous liquid, it is advisable to wait an additional one or two seconds at the first stop point before pressing to the second stop point.
5. Matters needing attention
5.1 The liquid taken before taking the liquid should be balanced at room temperature (15-25 ° C); if the liquid suction temperature is different from the room temperature, pre-wash the pipette tip multiple times before use. Note that the pipetting temperature must not exceed 70 ° C.
5.2 The depth of the tip immersed in the liquid should be appropriate, and the process of aspiration should be kept as constant as possible.
5.3 When aspirating liquid, it should be aspirated slowly and uniformly to avoid liquid splashing on the pipette head.
5.4 When adjusting the knob of the liquid volume, each time <1 turn, do not use excessive force, and pay attention to the value displayed by the counter not to exceed its adjustable range.
5.5 During the sampling process, the adjustable pipette should be careful not to touch the nozzles to avoid contamination; the nozzle box (shelf), waste bottle, reagents and sample tubes should be placed reasonably. , In order to facilitate the operation process and avoid pollution as the principle.
5.6 Change the nozzle before changing different liquids, samples or reagents; if there is residual liquid in the nozzle, replace it with a new nozzle.
5.7 Pre-wash the new nozzle before use. Inhale the liquid sample once and drain it back to the original container, repeat 2-3 times. This is because the liquid sucked for the first time will form a liquid film on the inner wall of the suction nozzle, resulting in measurement error. The liquid film remains relatively unchanged during the continuous operation of the same suction nozzle, so the second suction can eliminate the error. When the liquid volume is less than 10 mL, only when there is no pre-washing, at the same time, the sucked liquid should be repeatedly beaten in the liquid to be transferred several times, the liquid is emptied, and then the nozzle is lifted and stuck to the wall for 1-2 seconds In order to ensure the precision and accuracy of taking liquid.
5.8 Do not lay the pipette upside down or upside down when there is liquid in the nozzle to prevent the liquid from entering the pipette sleeve.
5.9 After using acid or corrosive vapor solution, it is best to remove the sleeve and clean the piston and seal ring with distilled water; do not lubricate the piston and seal ring with grease or the like. Pipettes that have been disassembled and washed must be calibrated before use.
5.10 Continuously adjustable pipettes should be placed on the pipette rack after use, away from moisture and corrosive substances.
5.11 Professionals should be regularly calibrated and commissioned, and not disassembled by themselves.
6. Troubleshooting
6.1 The possible causes and solutions for gas leakage or inaccurate measurement are:
Sleeve nut loose? ——Tighten the nut by hand.
The sleeve is scratched or broken? ——Remove the catapult and check the sleeve. When installing the sleeve, hand tighten the nut.
Is the piston or seal chemically corroded? ——Replace the piston and sealing ring. Wash the inner wall of the sleeve with distilled water.
6.2 If there is liquid in the sleeve, it can be cleaned according to the following method: remove the ejector, unscrew the nut and wash the sleeve, piston, seal ring and O-ring with distilled water, and reassemble after completely dry.
6.3 If bubbles are found during suction: drain the liquid back to the original container, check whether the suction nozzle is suitable for immersion in the liquid, and then suck the liquid more slowly; if there are still bubbles, the suction nozzle should be replaced.
6.4 All pipettes with replaced pistons or joysticks must be fully adjusted
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