How to choose the pipette tip

The tip, like the bullet of a gun, is an indispensable accessory for pipettes. In theory, the quality of the tip has a great influence on the accuracy of pipetting, and its importance is no less than that of a Pipette. However, the position of the tip in China is very embarrassing - most users prefer to buy high-quality pipettes at high prices, and are not willing to use better tips (this phenomenon has government in universities, research institutes, hospitals, etc.) The units of the background are very common). Therefore, the credibility of the data made in this case will inevitably require a discount - of course, this is also a Chinese characteristic.

Material. Currently, the tips on the market are basically made of polypropylene plastic (a colorless transparent plastic with a high chemical inertness and a wide temperature range). However, the same polypropylene, the quality difference will be great: high-quality tips are generally made of natural polypropylene, and cheap tips are likely to use recycled polypropylene plastic (in this case, we can Said that its main ingredient is polypropylene). In addition, most of the tips will be added with a small amount of additives during the manufacturing process. Common ones are: 1. Color-developing materials. The blue gun head (1000ul) and the yellow gun head (200ul), commonly known in the market, add corresponding chromogenic materials to polypropylene (we hope to be high-quality masterbatch, not cheap industrial pigments); 2, release agent. Help the tip quickly disengage from the mold after forming. Of course, the more additives, the higher the probability of an undesirable chemical reaction taking place during pipetting. So it is best not to add additives! However, due to the relatively high requirements on the production process, the tips without additives are rare in the market.

package. The packaging of the tips is mainly in bags and boxes. In relatively mature markets, boxed products account for the majority; in China, bagging is currently the absolute mainstream – mainly in bags. The so-called bag is to put the tip in a plastic ziplock bag, 500 or 1000 per bag (the number of bags per lot will be much less). Most users will buy the bagged tip and then manually put the tip into the tip box. Although China's labor force is relatively cheap, it also increases the chance of pollution! In addition, in recent years, a new form of packaging has emerged, which is a refill (8 or 10 plate tips stacked in a tower shape, which can be quickly loaded into the tip box without touching the tip). This type of tip requires less storage space and significantly reduces the use of plastic to achieve environmental protection. Although the domestic share of this form is still very small, it must be the general trend in the long run.

price. We first discuss the bagged tips (based on 10ul, 200ul and 1000ul, 1000 bags per bag) - the teacher told us that we must catch the main contradiction. The bag tip is mainly divided into three grades: one, the imported tip. According to the deaf people, the most expensive is EPPENDORF, a bag of 400-500 yuan, and sales slightly larger, such as BRAND, RAININ, etc., generally 100-150 yuan; Second, imported brands, domestic production (that is The so-called "fake foreign devil"). The representative brand of this grade is Axygen, its price is generally 60-80 yuan; three, domestic tips. The price range of domestic tips is generally 30-60 yuan. There are two representative products, one is the tip of Gongdong (it is better in domestic tips), and the other is the tip of Haimen (Haimen is a very important production base of plastic consumables in China. There are many tips in this place. Manufacturers, these manufacturers are usually characterized by small scale, poor production environment, poor quality control or no, but the price of their products is very low). The second is the boxed tip and the refilling tip. The price of the boxed tip is 1.5-2.5 times that of the bag tip, and the refill tip is 10-20% cheaper than the box tip.

In addition to the materials, packaging, and pricing discussed above, there are some things that are not usually mentioned but are equally important.

Special tips. The so-called special tips are specially designed for special samples or special applications. There are mainly the following categories: First, the gel tip (spotted tip). The tip of the tip is flat or very thin, mainly used for electrophoresis experiments; second, wide mouth tips. The tip of the tip is larger than usual, and is mainly used to remove macromolecular solutions such as proteins; third, low adsorption tips. The inner wall of the tip is specially treated to reduce the surface adsorption force and is used to remove the viscous liquid. Fourth, the tip is lengthened. Used for taking liquid in a container such as a volumetric flask; five, an external piston type tip. Mainly used on special pipettes, such as external piston pipettes and continuous distributors.

Adaptability. Not all tips can be used on pipettes of any range of the same range, so we have to remind the user to pay attention to the fit of the tip. In this regard, we can interpret the problem of adaptability from the following aspects: First, the specificity of the tip. Some brands of pipettes of some brands can only use their own tips, and other tips cannot be used at all. For example, RAININ's multichannel pipettes must use RAININ's LTS tips; second, the degree of adaptation. The most common situation is that a pipette can use a variety of tips, but the effect of pipetting is uneven. For example, the multi-channel pipette of EPPENDORF uses the tip of EPPENDORF, which is the first-class stick for both the feeling of pipetting and the accuracy of pipetting, but the multi-channel pipette of EPPENDORF is not satisfactory with Axygen's tip; Third, the range is adapted. Generally speaking, the maximum range of the pipette is less than or equal to the volume of the tip. For example, a pipette with a maximum range of 1000 ul uses a 1000 ul tip, while a 200 ul tip has a larger fitting range and can be used for a maximum range. 20ul, 100ul and 200ul pipettes; 4, the speciality of the large-scale pipettes (5ml, 10ml and 20ml) tips. Large-scale pipettes of various brands often require their own tips, making it difficult to find alternatives. Therefore, if you need to purchase a tip, we recommend that you tell the supplier the model of the tip you are using or at least the brand and range of the pipette you are using.

Biological pollution. Now, more and more users will ask for no RNase, no DNase, no DNA, no pyrogen and ATP contamination. This is a good phenomenon, but I have to remind two points: First, the high temperature sterilized tip does not guarantee no biological pollution, and it is necessary to carry out gamma ray to ensure no biological pollution.