1. Ensure the airtightness of the seal of the vaporization chamber

a. The service life of the silicone rubber pad of the inlet is related to the temperature of the vaporization chamber. Generally, it can be used for dozens of times. When the silicone rubber pad leaks, it will cause the baseline to fluctuate. .

b. Due to the excessive puncture of the injector, the silicon rubber pad debris enters the vaporization chamber. If there is too much debris, high temperature will affect the stability of the baseline or form ghost peaks.

Therefore, in order to ensure the normal operation of the analysis, please replace the seals frequently and check the gas tightness of the vaporization chamber frequently.

2. Regularly clean the vaporization chamber or liner

a. Due to long-term use, a large amount of high-boiling substances are often accumulated in the vaporization chamber and the liner. If a high-boiling point analysis occurs in a certain analysis, excess peaks will escape and affect the analysis. Therefore, the vaporization chamber should be cleaned with organic solvents frequently And liner.

b. Cleaning the vaporization chamber: remove the chromatographic column, and under the condition of heating and ventilation, inject absolute ethanol or acetone from the inlet, repeat several times, and finally heat and ventilate to dry.

3. Frequent leak detection of the gas circuit

a. Under normal circumstances, the leak detection has been carried out when purchasing a new instrument, but if the sensitivity is reduced, the retention time is prolonged, and the wavy baseline is found during use, the leak should be re-checked, especially the hydrogen gas circuit. Leaks should be checked frequently to avoid danger.

b. Some control valves use "O" shaped rubber rings, which may leak due to long-term wear; the silicone pad at the inlet is not changed frequently, and the chromatographic column is not properly connected ... all may leak. Therefore, leaks must be checked frequently!

4. Cleaning of Thermal Conductivity Detector (TCD)

a. Remove the chromatographic column, replace it with an empty short chromatographic column, pass the carrier gas, raise the temperature of the column oven and the detection chamber to 200-250 degrees, inject 2ml of organic solvent from the inlet, repeat several times, Ventilate to dryness.

b. Never use bridge current during cleaning. Otherwise it will damage the detector !!!!

5. Cleaning of Electron Capture Detector (ECD)

a. The cleaning method is the same as the thermal conductivity detector.

b. For cleaning organic solvents, electronegative organic solvents such as chloroform and carbon tetrachloride cannot be used, and benzene and n-hexane can be used. At 250 degrees.

c. For the radioactive source, the temperature of the Ni63 detector is between 250-300, and the temperature of the tritium scandium source should not be high

d. Do personal protection when necessary when cleaning ECD !!

6. Cleaning of hydrogen flame detector (FID)

a. The purpose of cleaning is to improve the insulation of the detector.

b. When the pollution is serious, the collector, polarizer and nozzle can be removed. The collecting pole and polarized pole can be scrubbed with absolute ethanol. The base and nozzle are repeatedly washed with organic solvent. The vent line should also be thoroughly cleaned. The nozzle mouth should be smooth and smooth. If there are burrs, use oil stone or assorted files and sandpaper to polish it. Rinse repeatedly with ethanol, and then dry alternately with hot and cold air.

c. The insulators fixing these electrodes can be soaked in absolute ethanol for 10-15 minutes, and wiped clean with silk or gauze. Dry to be installed.

d. When assembling, it should be restored to its original state, so that the top view of the nozzle, the polarized pole and the collector pole are concentric, and the side-view polarized pole and the nozzle mouth are at the same level.

e. Note: After cleaning, all accessories are forbidden to touch by hand, wear clean gloves when installing, and clean and dry all tools before use.

7. Cleaning of nitrogen phosphorus detector (NPD) and flame photometric detector (FPD)

Since the above two detectors are basically similar in structure to the FID, the cleaning method refers to the cleaning of the FID. NPD pays attention to the cleaning of rubidium baht; FPD should pay attention to the cleaning of light windows, but be careful not to expose the photocell to strong light

How to prevent fouling on FID collector

When removing the scale of the collecting electrode and disassembling and cleaning the FID, the nozzle is often disassembled, causing irreparable loss. According to the working principle of FID, the collector is high impedance to ground, generally above 107 ohms, so the general pollution of the collector or the poor connection between the collector and the electrometer will not cause serious noise unless the sensitivity operation is restricted. Therefore, when the FID is encountered with spike noise (baseline glitch), it is not recommended to disassemble and clean the FID detector first, but to find other causes of noise such as:

1. Whether the air flow ratio is appropriate;

2. The vaporization chamber is seriously polluted;

3. Severe column loss (not enough aging);

4. The electrostatic amplifier is unstable;

5. Polarization voltage is unstable;

6. Poor connection of signal connection;

7. Unstable utility power;

8. Incorrect grounding;

9. The data processor is faulty or the parameter setting is unreasonable;

10. Poor gas purity (especially when using various gas generators);

11. After the column is connected, there is a serious leak in each connector.

We often see that the detector, especially the white powdery material deposited in the electrode, is caused by the loss of silica generated by the silicone-based stationary phase after burning in the FID. To prevent the accumulation of silica in the detector, pay attention to the following points:

â‘ The spectrum column is fully aged before connecting to the detector.

â‘¡ It is better to use the stationary phase OV-101 with higher purity (such as chromatographic grade purity); less use of DC-200 with poor purity.

â‘¢ In the case of satisfying the FID sensitivity requirements of the analysis, try to select a larger air flow rate in order to expel various combustibles from the FID. After confirming that FID pollution may cause some kind of pulse spike interference noise.

There are three methods for removing scales for your reference.

â‘ : Inject a few microliters of freon, burn to form hydrogen fluoride, and the hydrogen fluoride and silica react to form volatile substances.

â‘¡: Remove the relevant parts of the detector such as: collector, nozzle, housing, insulator, etc. Wash for two hours in an ultrasonic bath and rinse with distilled water. Before loading the detector, rinse it with acetone again.

â‘¢: If there are too many dirt deposits on the collecting part, it is also a good method to use fine-grained sandpaper for cleaning

5 Pairs Lashes

5 Pairs Lashes,Classic Lashes,5 Pairs Eyelashes,Natural False Eyelashes

Zhengzhou Cuka Electronic Commerce Co., Ltd. , https://www.cukeyelashes.com