Four key factors that must be noted when using liquid chromatographs

As one of the high-end instruments necessary for the analytical laboratory, the liquid chromatograph is a high-frequency instrument for laboratory analysts. Even if the experienced old driver who is often used in the process is inevitable, it is often neglected. This causes some instrument failures. The convenient and fast analysis process is important, but it is always wrong to ignore some of the detailed steps for multiple samples. This article takes four key factors in the use of the liquid chromatograph and is extremely important for proper use.

1. The liquid chromatograph itself:

There is generally no problem with the instrument itself, especially the new instrument that has just been bought. The most important thing for the instrument itself is the calibration of the instrument. The instrument that has just been bought is generally confirmed by the seller (including IQ, PQ, OQ). After confirming the smooth passage, please ask the national or provincial level. The calibration of the instrument verification bureau can be used with confidence after the verification. In addition, some well-doing companies will perform internal verification of the instrument once every six months, in order to ensure the normal operation state of the instrument. .

2. Chromatographic conditions:

Chromatographic conditions generally include mobile phase, column, detection wavelength, flow rate, and injection volume.

The mobile phase involves the water and reagent test solution used to prepare the mobile phase. The water generally requires ultra-pure water or other water to have a resistivity of not more than 18.2 megohms. The reagent test solution requires chromatographic grades because the water is prevented. Interference with impurities in the reagent solution to the chromatographic results.

Columns will have different requirements for different varieties, but each column has its cleaning requirements. This can be found in the column manual. It must be done according to the above requirements, otherwise the column efficiency will be reduced. The service life of the column is shortened, and the detection wavelength will also have different requirements depending on the variety. It should be noted here that the change of the xenon lamp energy of the detector should be observed. For example, the baseline fluctuation is large, and the response value of the active component suddenly becomes small. Etc., it may be caused by insufficient energy of the xenon lamp. It is generally recommended to use 800 hours, but in fact, the use time is not limited, and can be replaced according to actual conditions.

The flow rate also varies from species to species, typically 1.0 ml/min. The flow rate is not arbitrarily changeable, especially as a QC person, but as a researcher, sometimes the flow rate is changed in order to explore conditions or perform method durability verification. To applicability of the evaluation method. For the injection volume, there are different regulations for different varieties. If the six-port valve is used for automatic injection, the precision of the injection is very good, and no need to emphasize anything.

3. Operator:

First of all, as a liquid chromatograph operator, you must carefully study the night vision instructions, master the operation of liquid phase hardware and software, master daily maintenance, and master the troubleshooting and maintenance of the most basic faults.

The operating procedures of the general liquid chromatograph are also drafted by the operator, so as long as the operation is strictly in accordance with the operation requirements, there is generally no problem. Of course, the gel needs to be specially pointed out to be important for the daily maintenance of the liquid phase, such as mobile phase. Filtration, degassing, cleaning of pump seals, cleaning of system piping, cleaning of solvent filter heads, etc., if not adhered, can easily lead to unnecessary malfunctions such as blockage of the column, excessive system pressure, abnormal chromatographic peaks, etc. waste time.

Secondly, when the operator prepares the liquid chromatograph for the sample solution to be tested, it is best to be completed by the same person alone, so as to avoid unnecessary accidental errors and cause analysis failure or error.

4. Liquid phase installation environment:

The liquid chromatograph should be installed on the countertop of the house horizontally and away from vibration and electromagnetic interference. If possible, separate the liquid phase data processing system. One is to prevent the baseline noise of the chromatogram from being too large, and the baseline is unstable. It is to reduce the harm to the human body.

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