In modern analytical laboratories, the automatic sampler is like a precise and efficient "ingredient master", orderly feeding various samples into the analytical instrument. However, if the cleaning and maintenance of the sample are ignored, residual samples may quietly infiltrate the subsequent analysis process like invisible killers, seriously interfering with the accuracy and reliability of experimental results. Therefore, it is of great significance to do a good job in cleaning and maintaining equipment.

Sample residue isautosamplerOne of the main challenges faced. After each injection, trace amounts of samples inevitably adhere to the injection needle, flow cell, and inner walls of connecting pipelines. These residual substances gradually accumulate over time, and not only will they mix into the new sample during the next injection, causing abnormal peak shapes and worsening tailing phenomena, but they may also breed microorganisms and further contaminate the entire system. Especially after processing high concentration samples or complex matrix samples, residual issues become more prominent.

For the key component of the injection needle, its cleaning needs to be particularly meticulous. Specialized organic solvents can be used for ultrasonic cleaning. First, remove the injection needle and soak it in an ultrasonic cleaner containing a suitable solvent (such as methanol, acetonitrile, etc.). Set the appropriate time and temperature parameters, and use the cavitation effect of ultrasound to strongly remove the sample residue attached to it. After cleaning, rinse off the solvent with pure water and blow dry with nitrogen to ensure that there is no residual moisture and the needle body is unobstructed. For stubborn stains, you can also try using a cotton swab dipped in a small amount of weak acidic or weak alkaline solution to gently wipe, but be careful not to damage the needle tip.

The circulation pool is also prone to accumulating dirt and grime. Due to its complex internal structure, ordinary flushing is difficult to remove dirt. At this point, the reverse flushing method can be used, which allows the cleaning solution to flow in from the outlet and out from the inlet, using the force of liquid flow to remove particles and dissolved impurities from the pool. At the same time, the use of surfactant solutions for cyclic cleaning can effectively decompose oily pollutants and improve cleaning effectiveness. After cleaning, rinse thoroughly with a large amount of deionized water and check for any bubbles. If there are, it indicates that there are still impurities that have not been removed, and continue cleaning until there are no more bubbles.

The connecting pipeline should not be overlooked either. Although regular replacement of pipelines is an ideal measure to prevent residue, the cost is relatively high in practical operation. A more economical and practical method is to use a high-pressure pump to push cleaning solution to flush the pipeline. Choose a cleaning solution that is compatible with the sample, set a higher pressure and flow rate to create turbulence in the pipeline, and vigorously wash away residual substances inside the pipe wall. In addition, online filters can be used to intercept larger particulate impurities and reduce their deposition in pipelines.

In addition to the cleaning of the local components mentioned above, the maintenance of the overall system cannot be ignored. After each experiment, the automatic sampler should be allowed to idle for a period of time to try to empty the remaining sample solution in the system. At the same time, regularly calibrate the various parameters of the instrument according to the requirements of the instrument manual, such as injection volume, injection speed, etc., to ensure that it operates in the best working condition.

Establishing a comprehensive cleaning record system helps track the cleanliness status and maintenance history of equipment. Record the time of each cleaning, the reagents used, the problems encountered and their solutions, etc., in order to promptly identify potential problems and take corresponding measures. Through continuous and effective cleaning and maintenance work, we can minimize the impact of sample residue on analysis results, ensure the accuracy of experimental data, and make the automatic sampler always a powerful assistant in the laboratory, providing strong support for scientific research and quality control.