Atomic absorption spectrophotometer with low ion concentration can stabilize readings.

In fact, the design principle and working principle of atomic absorption spectrophotometer allow the absorbance to vary within a certain range, that is, the instrument has a certain degree of accuracy and accuracy. For example, the accuracy of EppendorfBiophotometer is less than 1% (1A). The result of such repeated tests is normal in the range of about 1%. In addition, the physicochemical properties of nucleic acid itself and the pH value and ion concentration of the buffer solution for dissolving nucleic acid should be taken into account. In the test, too high ion concentration will also lead to reading drift. Therefore, it is recommended to use a buffer solution with a certain pH value and low ion concentration, such as TE, which can greatly stabilize the reading. The dilution concentration of the sample is also an important factor: because there are inevitably some fine particles in the sample, especially nucleic acid samples. The presence of these small particles disturb the test results. In order to minimize the impact of particles on the test results, the absorbance value of nucleic acid should be at least 0.1A, and the absorbance value should be at least 0.1-1.5A. Within this range, the interference of particles is relatively small, and the results are stable. This means that the concentration of the sample should not be too low or too high (over the scope of the photometer). Finally, the operation factors, such as mixing to be sufficient, otherwise the absorbance value is too low, or even negative; mixing liquid can not exist bubbles, blank liquid without suspended matter, otherwise the reading drift is intense; must use the same colorimetric cup test blank liquid and sample, otherwise the concentration difference is too big; conversion coefficient and sample concentration unit choose one As a result, the colorimetric cup can not be used for window wear; the volume of the sample must reach the minimum volume required by the colorimetric cup and so on.

An important accessory of spectrophotometer -- colorimetric cup

The colorimetric cup can be roughly divided into quartz cup, glass and plastic cup. According to different measuring volumes, there are colorimetric cups and capillary colorimetric cups. Quartz cup or glass is generally used for nucleic acid and UV quantitative protein testing, but it is not suitable for colorimetric determination. Because reactive dyes (such as Coomassie Brilliant Blue) can stain quartz and glass, disposable plastic cups must be used. Plastic cups are generally not suitable for testing samples in the ultraviolet range.

Due to the different sample size, the general spectrophotometer manufacturers provide different volumes of colorimetric cups to meet the different needs of users. At present, there is a kind of plastic cup which can be used not only for nucleic acid and ultraviolet protein quantification, but also for protein colorimetric determination. The sample dosage is only 50 ml. The cup can be packed in a single aseptic package and the sample can be recovered. For example, EppendorfUVette® the plastic colorimetric cup is an innovation in the market of colorimetric cups. With the development of life sciences and related disciplines, higher requirements have been put forward for the experimental research of such sciences. Spectrophotometer will be an indispensable instrument in molecular biology laboratory, and also become one of the necessary equipment in microorganism, food, pharmaceutical and other related laboratories.

With the development of technology, colorimetric cups are no longer necessary for spectrophotometric timing. Compared with the old spectrophotometer, the ND1000 spectrophotometer produced by the foreign Nanodrop Company (which has been acquired by ThermoFisher Company) can be used without diluting the sample, without using the colorimetric cup, and only 1-2 ml sample is needed for each measurement.

Manufacturers of atomic absorption spectrophotometer