When the liner or injection port of a gas chromatograph is contaminated, it often causes changes in the chromatographic characteristics of the sample, such as peak asymmetry (tailing or protrusion), spectral distortion, and so on. To ensure the separation efficiency of the instrument and the precision and accuracy of the analysis results, it is necessary to regularly maintain the liner and injection port. So, how to maintain the liner and injection port of a gas chromatograph?!

Why do gas chromatograph liners and injection ports need regular maintenance?

① The inner wall of the lining tube is contaminated or there is debris from the injection spacer, which can easily lead to poor reproducibility of the analysis results (such as retention time, peak area, etc.) or the appearance of ghost peaks;

② Improper filling of quartz glass wool and other fillers in the lining tube, or the presence of active spots on the inner wall of the fillers and lining tube, can easily lead to repeated and poor experimental results.

③ After prolonged operation of the gas chromatograph, solidified samples often remain at the injection port. When there is sample residue at the injection port:

a、 If the solidified sample remains on or under the injection pad, it is easy to cause difficulty in inserting the sharp tip of the injector during injection;

b、 If the solidified sample remains inside the diversion pipeline, it will cause the inner diameter of the pipeline to become thinner or even blocked; c. When the inlet temperature is much higher than the usual operating temperature, the previously solidified sample may exhibit ghost peaks, which can affect the reproducibility of the analysis results.

How to maintain the liner and injection port of a gas chromatograph?

Although the requirements for the structure of the liner are different for split/non split injection ports, packed column injection ports, and large-diameter capillary column injection ports, the maintenance methods for liners with different structures are basically the same. To reduce the impact of contamination of the liner and injection port on the measurement results, it is necessary to regularly inspect and clean the interior of the liner and injection port, as well as the transition joints of the injection port. If necessary, the liner should be replaced. For the maintenance of liner and injection port, it is generally divided into daily maintenance and regular maintenance.

1. Maintenance of lining tube:

① Daily maintenance of lining pipes

Cleaning the liner is a common maintenance method, which is suitable for situations where the inner wall of the liner is contaminated or there is debris from the injection pad.

1) Carefully remove the liner from the instrument, use tweezers or other small tools to carefully remove residual debris and fillers such as glass wool inside the liner, and do not scratch the surface of the liner during the removal process. First, remove the graphite pressure ring (or silicone rubber ring) on the upper end of the lining tube, which is prone to solvent attachment and can cause ghosting. Soak the liner in an organic solvent (such as acetone).

2) Wipe the inner wall of the lining tube with gauze dipped in solvent (such as acetone, etc.). If the severe dirt on the inner wall of the liner cannot be wiped off, the liner can be immersed in organic solvents (such as acetone, etc.) and left for several hours until the inner wall can be wiped clean with a gauze dipped in the solvent.

3) Dry (or blow dry) the lining tube, insert new filling material, and install the lining tube.

② Regular maintenance of the injection port

Replace the spacer; Clean or replace the injection needle; Conduct leak testing and repair; Clean or replace the lining tube/insert; Replace the O-ring; Clean or replace the splitter plate and metal gasket (SSI), etc.