Pipette tips, like gun bullets, are accessories for pipettes. In theory, the quality of the tip also has a great influence on the accuracy of pipetting, and its importance is no less than the pipette itself.
First, the special suction head.
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 spotting tips): the tips of the tips are either flat or very thin, and are mainly used for electrophoresis experiments; the second category is wide-mouth tips: suction tips The diameter of the tip of the tip is larger than that of ordinary tips, and it is mainly used to remove macromolecular solutions such as proteins; the third type is low-adsorption tips: the inner wall of these tips has been specially treated to reduce the surface adsorption force and can be used to remove viscous Liquid; the fourth category is the extension tip: mainly used for taking liquid in containers such as volumetric flasks; the fifth category is the external piston tip: mainly used for special external piston pipettes and continuous dispensers on the pipette.
Second, the adaptability of pipette tips.
The adaptability of pipette tips is a point that users are paying more and more attention to. Why? Because not all tips can be used on pipettes of any brand and corresponding range, the editor reminds us again that users must pay attention to the adaptability of tips when purchasing tips. Mainly we can understand the adaptability of the tip from the following aspects: First, the speciality of the tip. Some series of pipettes of some brands can only use their own standard tips, and other tips cannot be used. Second, the degree of tip fit. A common situation is that a pipette can use multiple tips, but the effect of pipetting varies with different tips. In general, the standard tip is still the best. Third, the tip and 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; 10ml and 20ml) tip specificity. Large-scale pipettes of major pipette brands often require their standard tips, and it is difficult to find alternatives. Therefore, if we need to buy tips, it is recommended to tell the supplier the model of our applicable tips or at least the brand and volume of the pipette we use.
Third, biological pollution.
Now, more and more users will require that the tips are free of RNase, DNase, DNA, pyrogen and ATP contamination. This is a good phenomenon, but the editor has to remind two more points: First, the high-temperature sterilized tips cannot completely guarantee no biological contamination. To ensure no biological contamination, steps such as gamma ray treatment are required. Therefore, it is almost impossible for users to process ordinary tips into non-biological contamination tips, and the purchased non-biological pollution-free boxed tips should provide corresponding certificates to indicate the test data of the corresponding items. No data on the certificate or even a tip without a certificate can be proven to be completely free of contamination; secondly, bagged tips are even less guaranteed to be free of biological contamination. As long as the suction head comes into contact with the air, there is a possibility of biological contamination, and the ordinary ziplock bag cannot guarantee that the suction head will not touch the air at all during storage and transportation; in addition, the ziplock bag is sometimes punctured by the suction head. occur. Therefore, if you have high requirements for tips, be sure to check with the supplier whether the tips have a certificate indicating the test data of the corresponding item when purchasing.
Fourth, the suction head with filter element.
The filter tip is a filter (usually white) on the upper end of the tip. This filter element is generally made of polypropylene, similar to the filter structure of a cigarette. Due to the existence of this filter element, the pipetted sample cannot enter the inside of the pipette, thereby protecting the parts of the pipette from contamination and corrosion, and more importantly, it can also ensure that there will be no cross-contamination between samples. Therefore, filter tips are also an important tool for pipetting volatile and corrosive samples. Of course, the price of filter tips is relatively high compared to general tips, and the price in China is very low. In addition, there are very few domestically produced suction heads with filter elements, and its filtering effect is also unsatisfactory.