Audible noise, random ghost peaks, low sensitivity. These are typical characteristics of dirty FID detector.
The most common cause contamination sulfide is bleeding from the column. Burned stationary phase may be deposited on the nozzle surface of the detector and cause problems. However, the nozzle napalují and other contaminants.
You need to clean your detector?
The above-described problems, however, may not only be caused by contamination of the detector. The steps outlined below will help rule out other potential causes.
The carrier gas and the stationary phase bleeding
Possible source of contamination can be found not only in the detector itself, but also in front of him. Bleeding stationary phase column, septum, inlet contaminated, contaminated carrier gas ... To eliminate this source Blind FIDU corresponding input plug and turn the FID. If the problem ceases, search problem outside detector. No need to replace the liner? Septum? Clean inlet? What is the state column? Do you have a pure carrier gas? You do not have a leak in the system?
Hydrogen and air
Even hydrogen and air used in the sulfide can be a source of contamination. Attention: especially when problems emerged after replacing the cylinder.
Also improper flow / pressure of the two gases can be a source of increased noise and reduced sensitivity to ignition problems sulfide. Make flows through the meter.
I electrical interference may exhibit similar symptoms dirty FID. There may be a defect electrometer, poor contact or interference by other devices in the lab.
Make sure to unplug the power cord!
Remember that the detector may be hot!
When dismantling FIDU pay attention insulating parts. Use tweezers, whether these parts do not transfer dirt from your hands or gloves. Beware of possible scratches.
Remember that sometimes it may be easier to change the nozzle before it is cleaned. This is particularly true when the nozzle is heavily contaminated and sharply increases the risk of scratches during nozzle cleaning.
Remove the nozzle from the sulfide.
Place it in an ultrasonic bath with water and detergent and ultrazvukujte about 5-10min.
Use a tool or a suitable thin wire purge nozzle. Be careful. Any scratches may change the shape of the flame, increasing noise or loss of sensitivity.
Re-insert the nozzle into the ultrasonic bath and ultrazvukujte other 5-10min. From now handling the nozzle use only tweezers.
Rinse the nozzle with clean water.
Rinse nozzle small amount of methanol.
Blow nozzle stream of air or nitrogen.
Let dry nozzle.
Seskládejte FID. Pay attention to tightening. When you drag nozzle may cause its deformation!
After seskládání can connect column. It is appropriate to heat the FID temperature 10 ° C-40 ° C higher than the normal operating temperature of the detector. Note maximum temperature limit FIDU! Note the maximum operating temperature of the column!
How to keep your detector FIT
A new column is bleeding most. Install the column and into the inlet, as usual, but let the detector end freely in the furnace and condition the column. Then install the column and into the detector.
Use a good quality, low column bleed.
Moisture and oxygen in the carrier gas deplete the stationary phase of the column and cause a bleeding. Wear high-purity gases, molecular sieves, traps ... Check the tightness of the gas circuit.
Use appropriate septa with low bleed and change them often enough.
ECD is a specific and sensitive detector. Inappropriate behavior, however, can sharply reduce its lifespan. The gradual increase in signal at this detector normal. However, if an increase occurs abruptly or adding more of the symptoms worsening-noise desensitization search problem.
ECD contains radioactive material, therefore, mandated regular wear tests. It is forbidden to open or to interfere in any way.
ECD can be cleaned only thermally. Generally, cleaning is performed so that the ECD detector heated to a temperature close to its maximum operating temperature and impurities are burned. Before cleaning, be sure there are no leaks. Raising the temperature takes place gradually. Track signal. Increase the temperature by 10-20 ° C, the signal starts to grow. Wait for the signal to stabilize and begin to decline, then you can again increase the temperature. Upon reaching the desired temperature, wait for the signal to decrease the expected values.
Follow the instructions of your manufacturer, the procedure may vary.
If you heat detector installed column exceed the maximum operating temperature of the column or column Deinstall detector and replace the plug.
Do not ruin your detector!
Use good quality gas intended for ECD.
Use molecular sieves, traps for purification of gases.
When potížích- increase in signal noise worse, desensitizing like. Check system for leaks.