How to quickly troubleshoot the problem of gas chromatograph peak

Have you ever had a moment when the Labsolar-6A all-glass Automated online Trace gas analysis system, which is clearly a photocatalytic material with photocatalytic activity, did not peak in the gas chromatograph for a long time? On the correction curve, the gas chromatograph couldn't detect the target. 

 In view of the above gas chromatography problems, what should we do to make the experiment work properly?

First, the target gas generated by the photocatalytic reaction or the target gas used for calibration curve (hereinafter referred to as the target gas) is fed into the LabSOLAR-6A all-glass automatic online trace gas analysis system, and the target gas is fed into the gas chromatography through the all-glass online sampling/injection valve (A valve). The process of feeding into the gas chromatography is that the carrier gas of the gas chromatography will purge the target gas from the quantitative ring of the A valve into the chromatographic column, and then enter the detector for detection after separation. At this time, the peak of the target can be seen on the gas chromatography. So the reason why we can't see the peak of the target may be in 6A or gas chromatography, how to quickly troubleshoot, one by one. In view of the above gas chromatography problems, what should we do to make the experiment work properly? 

Figure 1 connection diagram of LabSOLAR-6A all-glass automatic on-line trace gas analysis system with gas chromatography. 

1. Check the operation of gas chromatography 

 1.1 Check the carrier gas of gas chromatography First confirm whether the partial pressure of the carrier gas cylinder connected to the gas chromatography reaches 0.4~ 0.5mpa, and then check whether the pre-column pressure on the gas chromatography reaches the set value. 

 The gas chromatographic column front pressure refers to the working pressure of the gas chromatography. Only after the working pressure reaches a predetermined value, the gas chromatography can work normally. Therefore, after determining the partial pressure of the carrier gas cylinder, the situation of the gas chromatographic column front pressure still needs to be determined. 

 As for the display of specific values, there are differences between different manufacturers or different types of gas chromatography. The display position can be divided into pressure gauge, display screen on the gas chromatography host, or gas chromatography workstation. For specific viewing methods and pressure requirements, please consult the corresponding gas chromatography engineer if you have any questions. 

Note at this point: 

 (1) After adjusting the carrier gas flow rate, if the pressure decreases significantly after half an hour, it is recommended to replace the new pressure reducing valve; 

 (2) Gas chromatography produced by different manufacturers, the partial pressure of the carrier gas cylinder will be different, are subject to the pressure of the field gas chromatography engineer after debugging, daily experiment use do not adjust the partial pressure valve of the carrier gas cylinder. 

 1.2 Check the detector of gas chromatography 

 The signal value of the detector can be used to judge whether the detector works normally, check whether the current of TCD is loaded, and whether the flame of FID burns (see Figure 1). 

FIG. 2 Signal fluctuation after loading current on TCD (left) and signal fluctuation after successful ignition of FID (right) 

1.3 Check the temperature of each module of gas chromatography Most of the gas chromatography with fault protection function, when the gas chromatography detection failure, gas chromatography will automatically turn off the temperature of each module, through automatic cooling to protect the gas chromatography, so before using the gas chromatography module temperature has reached the set temperature. 

2. Check the operation of labsolar-6A all-glass automatic online trace gas analysis system.

  The Labsolar-6A all-glass automatic on-line trace gas analysis system can be tested by injecting a certain amount of target gas into the gas chromatographic injector if the gas chromatographic status is normal. If the gas chromatography still does not peak after driving into the target gas, it can be determined that the gas chromatography is damaged, and the corresponding gas chromatography manufacturer needs to be contacted in time for maintenance; If the peak is normal, it may be the LabSOLAR-6A All-glass Automatic on-line trace gas analysis system that needs maintenance. 

 2.1 Check whether the quantitative ring is blocked 

 Disconnect the gc carrier gas from the labsolar-6A all-glass automatic online trace gas analysis system, and then remove the A valve to check for vacuum grease blockage in the quantitative ring (Figure 2). If the quantitative ring is blocked, it should be cleaned up in time to ensure that the quantitative ring can get the target gas normally, so that the experiment can be carried out normally. Note that it is important to perform proper instrument maintenance regularly! 

Figure 3. (a) quantitative ring (b) plug status (c) unobstructed status 

 Through the above investigation partners can quickly solve more than 90% of the peak problem, through the above method is still unable to solve the partners remember to contact Pofil technology after-sales service.