autosamplerThe reason for the unstable baseline and increased ghost peaks
　　
Phenomenon: Fig1a and Fig1b analyze the same standard. Fig1a Unstable baseline and increased ghost peaks; And Fig1b has a stable baseline and is a normal graph.
　　
Fig1a is a graph of unstable baseline and increased ghost peaks
　　
Fig1b is a normal chart and also a cleaned chart
　　
Reason: After excluding issues with the pump, mobile phase, and detector, this phenomenon indicates contamination of the injection system.
　　
Solution: Replace the original with a 5% aqueous solution of perchloric acidautosamplerDraw about 100mL of the cleaning solution with a syringe, fill the sample bottle with the above cleaning solution, replace the chromatographic column with a plastic damping tube, and connect the outlet of the damping tube to the waste liquid without connecting to the detector. Turn on the pump and set a regular flow rate. Set up an automatic injection program with an injection volume of 200 μ L and an analysis time of 1 minute for 20 consecutive times. After the end, replace the cleaning solution with pure water, fill the sample bottles with pure water, and follow the same procedure as above (considering the large amount of injection and repeated times, prepare 5 sample bottles containing appropriate amounts of liquid, place them in the sample tray, set the automatic injection program, draw 4 times continuously from each bottle, and draw a total of 20 times from 5 sample bottles to avoid emptying).
　　
Explanation: A 5% perchloric acid aqueous solution can effectively remove dirt from the system. If there is no perchloric acid, methanol or pure water can be injected multiple times for cleaning, which can also achieve the same effect.