Excerpt of pipette selection (purchasing)
2020-10-10 14:18:42
Pipette selection (1)
I used to write a similar stuff, which was posted on a website. Afterwards, it was quoted by some websites in whole or in part. (I wrote that Dongdong is basically not suitable for being quoted in all. It is a pity that quite a few people quoted. Did not take a serious look), this is far beyond my expectation! Seriously, my understanding of the pipette at that time was probably only equivalent to the level of the kindergarten. Now, looking at this stuff at the level of primary school, there are still many flaws in writing, which really makes me blush. Therefore, there is an impulse to rewrite.
The topic of "the choice of pipettes" should be said to be more relevant, but it is still a bit difficult to avoid the useless use of nonsense. Just open the bow without turning back, I can only write down the scalp.
The choice of pipettes is related to many factors, which can be classified as follows: First, the factors of pipettes, such as accuracy, range, material, design and price, etc. In recent years, the concept of ergonomics has also entered people's sight; Second, supplier factors, such as partnerships and services; third, user factors, such as usage habits and application areas. We will expand one by one later.
Pipette selection (2) accuracy
The accuracy of the pipette that the deaf says is accuracy and repeatability. In this regard, the expressions of various brands are not consistent, some say accuracy and precision, and some say system errors and accidental errors. But since it is my own stuff, no matter what others say, always prevail.
The so-called accuracy refers to the degree to which the measured value matches the true value (set value), that is, the difference between the measured value and the true value. In actual calculation, we often use the set value as the true value (for the absolute value) Most pipettes have a maximum range accuracy of about ±1%. The so-called repeatability refers to the degree to which a single measurement corresponds to the average. As for the specific calculation method, it is not very useful for the user, and I will further expand it later when discussing "calibration of the pipette".
For the vast majority of users, the accuracy of the product being tested before purchase is both difficult and unnecessary. Therefore, it is mainly based on technical data provided by the manufacturer. But here is a point to make it clear: don't easily trust the supplier's verbal commitment, be sure to check the manufacturer's brochure. Of course, although the pipettes of each brand will have relevant accuracy data in their brochures, the sources of these data are quite different. First of all, the original data is generated in the same way: randomly select a certain number of pipettes of the same type, take three spans (usually the maximum range of the pipette, 50% range and 10% range), repeat After the number of measurements, the accuracy value of each pipette is calculated. Secondly, the principle of data screening is different: a more cautious brand will select the data of a pipette with the lowest accuracy as the data in its brochure. The brand that rules the rules will select the average of the accuracy of each pipette, and the brand of the individual slick will select the data of a pipette with better precision or even the best! Therefore, "black and white" is not always credible, or we need to have eyes that can distinguish between true and false.
Generally speaking, the following two points are helpful for us to recognize the accuracy data in the brochure: First, the accuracy data on the manufacturer's Chinese version of the manual should be exactly the same as its English version. If it is inconsistent, there will be “cheatingâ€. Suspect; second, the brands that have a greater impact on the global pipette market, the technical data provided by them is more credible.
It is also necessary to mention that there are relevant metrological verification standards (JJG 646-2006: Pipettes of the People's Republic of China), which elaborates on the accuracy standards of the country. For this document, I would like to explain two shortcomings: First, the accuracy requirements of its small-range pipettes are too low. Currently, the factory standards of various brands on the market are much higher than the national standards. Second, the large-scale process The accuracy of the 10% range of pipettes (1000 ul and above) is too high. Currently, no brand's factory data can meet its standards.
See my blog for more content: http://pipettes.blog.163.com
Kn95 Face Mask,Disposable Kn95 Face Mask,Kn95 Respirator,Kn95 Particulate Respirator
Jiangyin Huashi Medical Equipment Co.,Ltd , https://www.medicalwellcare.com