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How to clean the gas chromatograph FID detector

Source:未知 Posted:2015-08-12 23:30 Browse:

FID detector in use, good stability, the requirements are relatively low, the use of common, but in the long process, it is easy to detect nozzle and collector coke and other problems, or organic matter deposited at the nozzle or collector and so on.
 
       FID organic deposition of coke or other issues, can be detected and collector nozzle with acetone, toluene, methanol and other organic solvents for cleaning. When coke thicker can not be cleaned, they can of coke thicker portion detector careful sanding with fine sandpaper. Note sanding process should not damage the detector. After the initial grinding is completed, the pollution section further wipe with a soft cloth, and finally washed with an organic solvent, usually can be removed.
 
   Agilent TCD detector of thermal cleaning methods can be used, as follows: Turn off the detector, the detector is removed from the column header, the column header box detector blocked with dead block, with reference to gas flow settings to 20 ~ 30 ml / min, set the detector temperature was 400 ℃, thermal cleaning 4 ~ 8 h, it can be used after cooling.
 
Domestic or Nissan TCD detector contamination using the following method:
        After the instrument downtime, the gas path imported TCD dismounted, followed by 50 ml syringe Acetone (or toluene, can choose different solvents depending on the chemical nature of the sample) of anhydrous ethanol, distilled from the intake port repeated injection of 5 to 10 times with suction Seoul ball slowly blowing from the air inlet, blow impurities and residual liquid, then reinstall inlet connector, power will rise Column 200 ℃, the detector temperature rose to 250 ℃, through the ratio analysis Operation flow is large 1 to 2 times the carrier gas, until the baseline is stable.
 
        For serious pollution, the outlet may be blocked by blocking the death, from the intake port filled with acetone (or toluene, can choose different solvents depending on the chemical nature of the sample), holding about 8 h, discharging waste, then as above deal with. Although the universal FID detector, but some material on this detector response with little or no response, these substances include permanent gases, halogenated silanes, water, ammonia, carbon monoxide, carbon dioxide and so on. Therefore, the detection of these substances should not be used when the FID.
 
        FID flame is burning hydrogen and air disturbs the measured substances ionized, so pay attention to security issues. When not connected to the column, do not open hydrogen valve, in order to avoid hydrogen into the oven. When measuring flow, it must not allow the hydrogen and air mixture, that is measured when hydrogen to close the air valve, and vice versa. FID sensitivity with hydrogen, the ratio of air and nitrogen have a direct relationship, so pay attention to optimization. Usually the proportion of the three should be close or equal to 1: 10: 1. Moreover, some instruments designed with different nozzles are used for packed and capillary columns, used to pay attention to see a description he said.
       Prevent contamination detector, the detector temperature should be below the maximum temperature of the column set practical work in general should be higher than the column temperature was 10-20 degrees, once the detector is contaminated, ranging from noise sensitivity decreased or increased, while point not on fire. Decontamination approach is clean, mainly cleaning the nozzle surface and a gas pipeline. The specific method is to remove the nozzle, followed by different polar solvents such as acetone, chloroform and ethanol immersion and ultrasonic bath ultrasonic 10min or more, you can also use a fine stainless steel wire through the hole in the middle of the nozzle, or with an alcohol lamp burning nozzle within the oil, in order to achieve thorough cleaning. After washing and drying of the nozzle, and then loaded on the detector measurement.