The periodic verification of imported gas chromatographs is a quality management method required for laboratory accreditation and metrological certification. It refers to the regular inspection of the gas chromatograph by the laboratory itself, which is used to check whether it can always maintain the accuracy of the calibration timing, timely detect and correct instrument and equipment errors caused by drift, aging, damage, sample contamination or other unknown reasons, ensure that the instrument remains in good condition during use, and maintain the credibility of the test results. The main content of gas chromatograph verification during operation is to check the stability, accuracy, and reproducibility of the chromatograph, mainly by detecting key performance parameters such as baseline noise and drift, minimum detection limit, and relative standard deviation.

Baseline noise and drift refer to the detection of whether the entire gas chromatography system, including the gas path, circuit, injection system, column system, detector, etc., is in good operating condition before injection. Imported gas chromatography is two basic comprehensive indicators that reflect whether the instrument is running normally. On the basis of normal baseline noise and drift, the separation method, separation condition selection, and operator proficiency are verified by injecting standard substance samples. Based on the detection results, the lowest detection limit and relative standard deviation of the chromatograph are calculated to test its sensitivity and reproducibility.

After the verification of the imported gas chromatograph is completed, the content of the verification and the results of the detection and calculation should be recorded in the form of a written report for future maintenance work to proceed normally.

When encountering baseline problems while operating a gas chromatograph, we first check whether the instrument conditions have been changed, whether the gas cylinder or other instrument accessories have been replaced. If there is no such situation, we need to further check whether the injection pad has aged. We should regularly replace the injection pad and develop good habits. If it is not an injection pad problem, we need to check whether the quartz wool needs to be replaced. In normal situations, we need to check whether the liner is clean. If the liner is confirmed to be clean, it may be a baseline problem caused by detector contamination, which can be solved by cleaning or hot cleaning methods.