Liquid chromatography Is an extremely accurate test instrument It has a wide range of applications in the environmental, food, biological, and pharmaceutical industries. This article briefly describes a few key points for the analysis of samples in a liquid chromatograph. The hydrogel Screen Protector has super ductility and shrinkage, has a strong and effective self-repair function, impact resistance, durability, better toughness, and has a certain buffering effect on sharp objects. The use of hydrogel film can adapt to the contours of any device, so it can be attached to curved screens and rounded edges. The full-coverage screen protector can perfectly fit your screen and provide maximum protection. Hd Clear Hydrogel Protector Sheet,Anti Blue-Ray Hydrogel Protector,Matte Hydrogel Film,Privacy Hydrogel Film Shenzhen TUOLI Electronic Technology Co., Ltd. , https://www.hydrogelprotectors.com
Flow ratio adjustment: China's drug standards do not specify the length of the column and the particle size of the filler. Therefore, the mobile phase must be readjusted each time a new sample is tested. Therefore, it is recommended to equip the sample with the appropriate amount of mobile phase for the first time. So as not to waste. For the preparation of mobile phase standards, the main peak should generally be adjusted to a retention time of 6 to 15 minutes. The reproducibility of the mobile phase of weak electrolytes is less likely to be achieved, and care should be taken to adequately equilibrate the column.
Sample preparation: After the sample solution is extracted from the sample material to be tested, it must be purified by crystallization by a nitrogen atomizer and then configured to a certain concentration of solution, and then filtered using a solvent filter before entering the instrument. In addition, the solvent used to hold the solution avoids the use of plastic materials. Plastic containers often contain high-boiling plasticizers, which may be released into the sample solution to cause contamination, and may also contain certain drugs, causing analysis errors. Some alkaline drugs are adsorbed on the surface of the glass container, which affects the quantitative recovery of the drug in the sample, so the glass container should be silanized if necessary.
Injection volume: The injection volume of the test sample is generally 10L, which is mainly determined by the specification of the loop. At present, most HPLC systems use 10L, 20L and 50L of the loop size, so it should be noted that the injection volume is consistent.
Recording time: After the sample enters the column, the first time, the blank solvent, the reference solution and the test solution should be injected into each shot, and the longer time spectrum (30 minutes or more) should be collected to determine. The position of the analyzed component peak in the sample, the resolution, the number of theoretical plates, and whether or not there are impurity peaks elute for a long time to determine whether it will affect the determination of the main peak.
Calculation: The calculation of the test results is mainly based on the chromatogram, which is the basis for the qualitative and quantitative analysis of the chromatograph. The horizontal axis of the chromatogram represents the retention time and can be used as a basis for qualitative analysis of the chromatographic instrument; the maximum value on the chromatographic peak is the basis for qualitative analysis, and the area covered by the chromatographic peak depends on the content of the corresponding component, quantitative analysis Basis. It should be noted that some of the reference materials are labeled with different amounts of sample, some are complex salts, some have different water content, some are different in salt base or some are marked with effective parts, so be careful when testing.
The precautions for the sample detection by liquid chromatography are as follows: 1 After filtering the mobile phase, observe whether there are particles or fibers that can be seen by the naked eye, and filter at least three times; when the column is online, increase the flow rate in steps of 0.1 ml/min. Carry out, generally no more than 1ml / min, and vice versa. Otherwise, the bed will collapse and cross the peak. When the column is not in line, it is necessary to increase the flow rate at a rate of 0.5ml/min (or down), and do not raise (lower) to avoid pump damage. 3 When installing the column, please pay attention to the flow direction, and do not leave any gap at the interface. 4 Please pay attention to the filtration of the sample solution (the injection can be filtered without filtration), and pay attention to the volatility of the sample solvent. 5 After the measurement is completed, please wash the column with water for 1 hour and methanol for 30 minutes. If it is still used the next day, rinse with water at a low flow rate (0.1~0.3ml/min) (note that the water is sufficient) without rinsing the methanol. In addition, special attention should be paid to the column with high carbon content and sufficient tailing, first rinse with water containing 5~10% methanol, then rinse with methanol. 6 Flush the column head with water at the same time (if there is automatic cleaning system, you should change the water).
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