Among the common analytical instruments in the analysis and testing laboratory, there is one instrument that we have mentioned, that is, the pocket colorimeter and the most common colorimeter is mainly the ultraviolet colorimeter, which is mainly used to measure the measured absorbance of a substance under irradiation of a certain wavelength. This kind of analysis can effectively quantitatively or qualitatively analyze the substance itself, but in the daily use process, some people have more or less doubts about the use of the colorimeter, and the use also there are some irregularities. Therefore, in the process of using the colorimeter and the problems that cannot be ignored, and some targeted solutions are taken, it is important to make it better to qualitatively or quantitatively determine the substance.
The problems in preheating of colorimeter
Using a colorimeter—generally requires preheating, which is usually explained in the instruction manual. Generally, the preheating time is about 20 minutes. However, if the colorimetric is a microprocessor, after turning it on, the machine will enter the automatic detection stage, which is what we often call the initialization state 0. This process takes about 10 minutes. When preheating the colorimeter, some users have certain problems. For example, it stops at the thermal circuit system after turning on the colorimeter, that is to say, the wavelength is not adjusted, and the absorption is not turned on. The battery box cover is preheated, and some people even think that the process of initialization is the process of preheating. This kind of mistake is very serious. The purpose of preheating the colorimeter is mainly to promote it to achieve the best use state, thereby effectively ensuring that the measured data is more stable and correct. The preheating of the colorimeter is not only for the stability of the electronic components of the circuit system, but also to ensure that the optical path system is in a stable state, so it needs to be preheated correctly.
The Problems of Using Absorbing Cells in colorimeter
Regarding the use of the absorption cell of the colorimeter, it must be rinsed with the solution to be filled before the absorption cell is filled with liquid, and it is generally rinsed 2 to 3 times. Whether it is necessary to use pure water for rinsing before rinsing requires a specific analysis of specific issues. If the liquid to be tested in the absorption cell is used for the first time, in order to better maintain and maintain the absorption cell, and to reduce the color adsorption capacity of the dry glass surface to a greater extent, so as to facilitate the absorption cell after use. For cleaning, you need to rinse it with pure water first, and then rinse it with the solution to be installed 2~3 times. If after that, use this absorption tank to install a concentration similar to the previous one, or higher than the previous concentration. When the solution is used, then you can directly use the solution to be loaded to rinse 2~3 times. The standard curve method is used for measurement. If the absorbance of the standard solution is measured first, then when the sample solution is measured, the concentration of the sample solution is lower than that of the last standard solution, or the concentration of the sample solution is lower. If it is unknown, then it is recommended to use pure water for rinsing first, and then rinse with the solution to be installed 2~3 times.
About the disposal of the colorimeter absorption cell after use
After the absorption cell of the colorimeter is used, its disposal problem is relatively simple. It needs to be rinsed immediately with tap water to ensure that it is clean, then rinsed with distilled water, and then placed. After the absorption cell is dried, it is placed the stored in the absorbing cell box. In the actual use process, many operators often just pour out the liquid to be tested, and then use distilled water for rinsing. In fact, this approach is very impossible.
About the repeatability of colorimeterabsorbance measurement problems.
When using a colorimeter for measurement, if it is found that the same solution has different results at different times, this can only mean that the repeatability of the measurement is not good, and analyze the reasons for the poor repeatability. There may be a factor of measurement error, but of course, there are other factors. Because the preheating time of the instrument is not enough, this problem may be caused, so the solution to this problem is to extend the reservation time, or use the correct preheating method to preheat it, and at the same time, if the photoelectric converter has been used for a long time, its photoelectric conversion efficiency has changed, which can also lead to the repeatability of the colorimeter absorbance measurement. In this case, the absorbance of the standard solution and the solution to be tested will be equally low, so when performing relative quantification, the results are not affected.
The impact will be minimal. For this type of instrument, it is recommended that the continuous use time should not exceed 3 hours. If it needs to be used for a long time, it needs to be intermittently used for 30 minutes.
The colorimeter is an instrument often used in the laboratory. In reality, many operators are not proficient in operating the colorimeter, and there are even erroneous operations. On the one hand, this will cause test results. The inaccuracy of the colorimeter, on the other hand, also greatly reduces the life of the colorimeter, so it is necessary to master the use of the colorimeterproficiently and clarify the related problems in the use process. Only in this way can we better. The application of the colorimeter to practice can better guide the actual work.