standard
1. Product performance, that is, the accuracy and repeatability of the pipette. For the vast majority of users, it is difficult and unnecessary to test product performance before purchasing. Therefore, it is mainly based on the technical data provided by the manufacturer. But still don't easily believe the seller's verbal promise, be sure to consult the written materials provided by the manufacturer.
2. The reliability and durability of the product mainly depends on the material used in the pipette. For the shell, it should have higher impact resistance, corrosion resistance and lower thermal conductivity (such as PVDF material); for the piston, there are mainly three materials in the market: stainless steel, ceramic and plastic. Stainless steel has good mechanical properties and long life, but it is not suitable for pipetting strong acids and alkalis; ceramics have high corrosion resistance but poor mechanical properties. Of course, high-quality materials often mean higher prices, so you need to consider the factors of purchase price and life span.
3. The ergonomic design of the product can mainly consider the following points:
First, the short moving distance of the thumb to complete a pipetting cycle means higher comfort;
Second, compare the thumb force required for a pipette of the same volume to complete a discharge (must be pressed to the end). This is the key to comfort. Less force means less risk of finger injury caused by long-term use;
Third, when loading and unloading the suction head, the less effort the better;
Fourth, the weight of the pipette is moderate, too heavy will increase the burden on the hand, but too light also often means that the material may be slightly worse;
Fifth, other auxiliary designs, such as the frosted design of the shell and the finger hook design, help to further improve the comfort.
use
Range adjustment
When adjusting the range, if you want to adjust the volume from a large volume to a small volume, follow the normal adjustment method and turn the knob counterclockwise; but if you want to adjust the volume from a small volume to a large volume, you can first turn the scale knob clockwise to over The scale of the measuring range is adjusted back to the set volume, so that the highest accuracy of measurement can be ensured.
During this process, do not turn the button out of the range, otherwise the internal mechanical device will be stuck and the pipette gun will be damaged.
Assembly of the pipette tip (suction nozzle)
When putting the pipette tips on the pipette gun, many people will knock on the pipette tip box a few times. This is a wrong approach, because this will cause the internal parts (such as springs) of the pipette tips to be damaged. The instantaneous impact force generated by the percussion becomes loose, and even causes the scale adjustment knob to jam. The correct method is to insert the pipette gun (apparatus) vertically into the tip of the pipette, and turn it left and right with a little force to make it tightly combined. If it is a multi-channel (such as 8-channel or 12-channel) pipette, you can align the first pipe of the pipette with the first pipette tip, then insert it obliquely, and shake it forward and backward to lock it. The sign that the gun tip is clamped is slightly beyond the O-ring, and you can see that the connecting part forms a clear sealing ring.
Method of pipetting
Before pipetting, make sure that the pipette, pipette tip, and liquid are at the same temperature. When sucking liquid, keep the pipette upright and insert the pipette tip 2-3 mm below the liquid surface. Before sucking the liquid, you can suck and put the liquid several times to wet the suction nozzle (especially when sucking the liquid with viscosity or density different from water). At this time, two pipetting methods can be adopted.
One is the forward pipetting method. Press the button with your thumb to the first stop, then slowly release the button to return to the origin. Then press the button to the first stop to discharge the liquid, pause for a while and continue to press the button to the second stop to blow out the remaining liquid. Finally release the button.
The second is the reverse pipetting method. This method is generally used to transfer high-viscosity liquids, biologically active liquids, easily foaming liquids or very small amounts of liquids. The principle is to suck in more liquid than the set range first, without blowing out the remaining liquid when transferring the liquid. First press the button to the second stop, and slowly release the button to the origin. Then press the button to the first stop to discharge the liquid with the set range, continue to hold the button at the first stop (don't press it down again), remove the tip with residual liquid, and discard it.
Correct placement of the pipette
After use, you can hang it upright on the pipette holder, but be careful not to fall off. When there is liquid in the pipette tip, do not place the pipette horizontally or upside down, so as to prevent the liquid from flowing back and corroding the piston spring.
maintenance
If not in use, adjust the range of the pipette gun to the maximum scale, so that the spring is in a relaxed state to protect the spring.
It is best to clean the pipette regularly, you can use soapy water or 60% isopropanol, then use distilled water to clean it, and let it dry naturally.
Before autoclaving, make sure that the pipette can adapt to high temperatures.
Calibration can be performed by repeating the method of weighing distilled water several times in an environment of 20-25 degrees.
Check if there is any leakage when using it. In the method, suck the liquid and place it vertically in the air for a few seconds to see if the liquid level drops. If the liquid leaks, the reasons are roughly as follows:
1. Whether the tip of the gun matches;
2. Whether the spring piston is normal;
3. If it is a volatile liquid (as many organic solvents are), it may be a problem of saturated vapor pressure. The liquid can be pipetted several times before pipetting.
