To improve the accuracy of the analysis results,
Various errors that may arise during the analysis must be considered,
take effective action,
Minimize these errors.
1. Sources of Errors During Sample Processing
The processing of the sample includes steps such as weighing, solubilizing, and labeling dilution. The sample processing should minimize the errors caused by the operator’s technical problems. The dilution times of the samples and the dilution tools are the sources of errors.
2. Source of manual injection error
As the main force of injection, it is still the manual injector. If used incorrectly, it can cause chromatographic problems, lack of linearity in standard curves, and poor repeatability. Regular cleaning and maintenance of the injection valve can avoid pollution and blockage caused by the injection valve, eliminate interference peaks, and improve accuracy. The injection volume should be more than 3 times larger than that of the quantitative loop, so as to prevent part of the sample from overflowing from the overflow tube and cause errors in quantitative analysis.
3. Sources of instrument systematic errors
Inaccuracies in the analysis results due to the failure of the infusion pump are common. Such as dust, garbage and other pollutants enter the infusion channel, causing pipe blockage, one-way valve pollution causing pressure instability, sealing gasket damage causing system leakage, and plunger rod damage causing no mobile phase to flow out and pressure fluctuations. It is very important to ensure the stability and normal operation of the infusion pump to the accuracy of the analysis results and to reduce errors.
Mobile phase causes changes in mobile phase composition
Error caused by configuration, proportional error caused by failure of online mixing pump, change of composition after placement. For example, with volatile solvents, vacuum degassing causes loss of volatile components; mobile phase absorption of carbon dioxide in the air causes pH changes. Changes in mobile phase composition have the greatest impact on components with large tR values. Small changes in reversed-phase solvent can cause considerable changes in retention times.
Change in temperature
There is no constant temperature device on the column, and the retention time usually changes due to temperature. A column oven should be used, and the minimum temperature difference in the room should be maintained.
After flushing the column for 30 minutes with the mobile phase, repeat the same sample every 10 to 20 minutes. If the retention time remains unchanged, it means that it has been balanced. It should be noted that the column may be equilibrated for one component and not yet equilibrated for other components. Therefore, the sample can only be formally analyzed if all components are equilibrated.
Improve operating skills, work carefully, carefully observe controllable errors, try to minimize controllable errors, and the accuracy of the analysis results will be higher.