ID common failure analysis and troubleshooting
2.1 Analysis of the causes of chromatographic peak failures after sampling and troubleshooting methods
2.1.1 No fire
The prerequisite for the previous work that we are not FID is ionization under the action of hydrogen flame, and the color of the fire will not be damaged after the injection. If there is a small drop of water on the vent lamp of the iron plate or glass glass detector, it proves that the fire has been lit; otherwise, it proves that the fire is not lit. Whether there is electron leakage or soap bubbles. Second, whether the gas flow is normal, whether the ratio of air to air is appropriate, whether there are dynamics of the gas that can be generated when there are bubbles, whether there is air flow and air flow, and adjust the various flow rates after ignition. To the optimal flow rate.
2.1.2 Signal output interrupt
The signal line is the channel for conveying the detection signal. If the signal line is damaged or short-circuited, the signal cannot be sent from the camera to the cake, and the nutrition cannot display the peak. Therefore, we must first check the connection of the signal line from the instrument to the workstation, and observe whether there is any poor contact or damage. In addition, you can use a multimeter to measure the spectral signal output after the sample is injected, and observe whether there is a signal output. If there is no signal output, it proves that the fault is introduced by the chromatograph. It is necessary to find the fault point in the chromatographic signal amplification part and deal with it.
2.1.3 Poor insulation of collector
The detection method is to collect the results of the pole and the instrument shell, and the result should be greater than 1kΩ. Otherwise, it is necessary to clean the collector individually.
2.1.4 Other reasons
Mainly include damage to the injection pad, failure of the column failure (capillary column is more common), damage to the micro-injector, etc.
2.2 Loud noise
2.2.1 Electrical reasons
The inspection method is to disconnect the detector's signal line and observe the running status in the acquisition state. If an emergency occurs or is clear, it means that the fault comes from the FID detector. You can change the detector and replace minor faults to eliminate the fault. Or other circuit reasons (such as damage to the power supply, whether the circuit board and various plug-ins are loose, or the instrument is poorly grounded, etc.), the way to check whether the grounding of the instrument is good is to measure the grounding resistance of the instrument with a multimeter to be less than 5Ω.
2.2.2 Measurement system pollution
Disconnect the signal line and check the operating conditions under the acquisition status. If the system is operating normally, prove whether the detection column is invalid (need to be processed), whether the chromatographic column is contaminated (glass filament, glass liner, etc.), and the detector is contaminated. The main cause is the contamination of the ion head, because there are a large amount of carbon compounds, and the detector needs to be carefully disassembled and cleaned with a neutral solvent.
2.3 Abstract peak of air peak
When analyzing trace amounts, such as the analysis of total hydrocarbons in acne, the oxygen signal peak retention time is shorter, which may be irritation, irritation, ethylene, etc. If the adjustment is not good, it will be cool or misinterpreted as a boast peak. In an instant, the energy expansion is gradually reduced, and a gradual peak can be observed when entering the sample, until the adjustment is relaxed until it is reduced.
3. Prevention of contamination of FID detector
When we detect and detect the detector, we often collect the collection in the detection instrument and the collector to form the collector and the collector to detect, especially the white powder substance deposited in the collector to form the substance. The type of stationary phase fault is diagnosed after the combustion in the FID. Deposits usually reduce and cause noise and spikes, and even affect the characteristics of the detector. To prevent accumulation in the detector, the following should be paid attention to:
(1) The front pillar should be equipped with equipment before connecting the detector to use;
(2) The best application purity accuracy (such as chromatographically pure stationary phase OV-101; less use of poor purity D-200;
(3) In the case of meeting the possible requirements of the analysis for FID, try to choose a larger air flow rate. Various combustion products leaving FID are confirmed to be FID pollution introduced.
4. FID detector removal method
(1) The formation of a few microliters of Freon will heat hydrogen fluoride to form hydrogen fluoride and cause substances after reaction;
(2) Remove the relevant information of the detector, such as: collecting electrode, sample part, shell, privacy body, etc.
In summary, FID is a high-precision detector in gas chromatograph, which affects the abnormal factors of the entire spectrum. To accurately determine the location of the abnormal phenomenon, it is necessary to fully understand the components and working principles of the FID detector. In the face of different failure phenomena, it is necessary to consider both the part and the whole. If there is a "result", there must be a "cause". Gradually eliminate the "cause" of the failure, avoid the failure and narrow the scope, and quickly eliminate the failure.