Precautions for pipette tips
Pipette tips on the market today are basically made of polypropylene plastic (a colorless, transparent plastic with a high chemical inertness and a wide temperature range). However, the same polypropylene can vary greatly in quality: high quality tips are generally made of natural polypropylene, while cheap tips are most likely made of recycled polypropylene plastic (in this case, the most we can say is that it is mainly polypropylene). In addition, most of the tips in the manufacturing process will also add a small amount of additives, the more common additives are:
1, color development materials. The market is commonly known as blue tips (1000ul) and yellow tips (200ul), is the polypropylene added to the corresponding color materials (as the user, then certainly hope that it is high-quality masterbatches, rather than cheap industrial pigments).
2. Release agent. Mainly used to help the tip quickly detach from the mold after forming. In this case clear, the more additives, the higher the probability that undesired chemical reactions may occur during the pipetting process. So the safest thing is to have no additives. But also due to the high demands on the production process, pipette tips with no additives at all are really rare on the market, so we users can only try to choose pipette tips with less additives.
Pipette tips are mainly packaged in bags and boxes. In the relatively mature market, boxed pouches are the majority; in the Chinese market, pouches are now the absolute mainstream - mainly because they are cheaper. The so-called bagged, is to put the suction head in a plastic self-sealing bag, 500 or 1000 pieces per bag (the number of large-range suction head per bag will be much less). Most users will buy the bagged tips and then manually place the tips into the Pipette Tip Box, secondarily increasing the chance of contaminating the tips in the process! In addition, a new form of tip packaging has emerged in recent years, the refill (8 or 10 plates of tips stacked in a tower, allowing the tips to be quickly loaded into the tip box without touching the tips). This type of pipette tip requires less storage space and reduces the use of plastic for environmental purposes.
In the previous article we discussed pipette tip materials and packaging, but there are also some things that are not usually mentioned by our users but are equally important: special pipette tips, pipette tip adaptability, pipette tip bio-contamination, and pipette tips with cartridges.
First, special tips.
Special tips are specially designed tips for special samples or special applications. There are mainly the following categories: the first category is gel tips (also known as spot tips): the tip of the tip is either flat or very thin, mainly used for electrophoresis experiments; the second category is wide mouth tips: the tip tip aperture is larger than the general tip, mainly used for pipetting large molecule solutions such as proteins; the third category is low adsorption tips: the inner wall of these tips is specially treated to reduce the surface adsorption, which can be used for pipetting viscous liquids; the fourth category is the extended tip: mainly used to take liquid in containers such as volumetric flasks; the fifth category is the external piston tip: mainly used on special pipettes such as external piston pipettes and continuous dispensers.
Second, the adaptability of pipette tips.
This point about the adaptability of pipette tips is a point of increasing concern to users nowadays, why? Because not all pipette tips can be used on any brand of pipette with the corresponding range, so once again, we remind our users to pay attention to the adaptability of the tips when purchasing them. There are several ways to understand the suitability of the tips: First, the specificity of the tips. Some brands can only use their own standard pipette tips, but no other tips are available. For example, Rainin's multichannel pipettes must use their own LTS tips; second, the degree of tip adaptation. The most common scenario is that a pipette can be used with multiple tips, but the pipetting results vary from tip to tip. In general, the standard pipette tips are the best, but some brands have good tips, such as Axygen. Third, the pipette tip and the pipette range should be adapted. In general, the volume of the tip should be greater than or equal to the maximum range of the pipette, for example, a 200ul tip can be used for pipettes with a maximum range of 20ul, 100ul and 200ul; fourth, a large range of pipettes (5ml, 10ml and 20ml) tip specificity. All major pipette brands tend to require their standard pipette tips for large volume pipettes, and it is more difficult to find a replacement. Therefore, if we need to purchase a pipette tip, it is recommended that we tell the supplier the type of tip we are using or at least provide the brand and range of pipette we are using.
Third, biological contamination.
Nowadays, more and more users are asking for pipette tips free of RNase, DNase, DNA, pyrogen and ATP contamination. This is a good phenomenon, but Yongyue has to remind two points again: First, autoclaved tips are not completely guaranteed to be free of biological contamination, and steps such as gamma ray processing are required to ensure that they are free of biological contamination. Therefore, it is almost impossible for users to process universal pipette tips into bio-contamination-free tips by themselves, and the bio-contamination-free boxed tips purchased should be provided with the corresponding certificate indicating the testing data of the corresponding items. No data on the certificate or even no certificate on the tip is not proof that it is completely free of contamination; secondly, the bagged tip is even more impossible to guarantee no biological contamination. As long as the suction tip is in contact with air, there is a possibility of biological contamination, and ordinary self-sealing bags cannot guarantee that the suction tip is completely free of air during the storage and transportation process; in addition, the self-sealing bags are punctured by the suction tip from time to time. Therefore, if you have high requirements for the suction head, then you must ask the supplier to understand whether the suction head comes with a certificate indicating the testing data of the corresponding items.
Fourth, Filter Pipette Tips.
With cartridge suction head is in the upper end of the suction head has a cartridge (usually white). This cartridge is generally made of polypropylene, similar to the cigarette filter structure. Thanks to this cartridge, the sample cannot enter the pipette, thus protecting the pipette components from contamination and corrosion and, more importantly, ensuring that there is no cross-contamination between samples. Therefore, cartridge tips are also an important tool for pipetting volatile and corrosive samples.
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