This Information Applies To: All Agilent Atomic Absorption Spectrometry Systems (AA50, AA55, AA240, AA280)
Issue: This article describes when and how to clean an AA burner.
For optimum and safe performance, burners (see Figure 1) should be cleaned after each day of use. Particularly if the solutions being analyzed have a high solids content or a rich nitrous oxide-acetylene flame has been used. If not cleaned regularly, hard deposits that are difficult to remove may build up and inhibit performance.
Hot Surface and Explosion Hazard
Parts in and near the burner compartment become very hot during operation. To prevent severe burns, always allow parts to cool down, or wear heat-resistant gloves before touching.
The burner is correctly assembled, sealed, and pressure-tested during manufacture. To prevent gas leaks and flashbacks, which may cause death, injury or property damage, the burner must never be disassembled, modified, or mistreated.
The correct procedure must always be used to clean the burner slot because the use of a burner with an oversized slot can cause a flashback.
Tip: It is impossible to determine with the naked eye whether a burner is clean. Even a low-power inspection lens will fail to show low levels of contamination. The best way is to use a binocular microscope, which allows you to look down inside the burner slot.
|Figure 1 - Burner
Steps to follow:
|Figure 2 - 1. Chimney 2. Flame Shield 3. Front panel
To clean the burner
Warning: Always wear Personal Protective Equipment when cleaning the burner
Tip: To speed up drying, dry the burner with a paper or lint-free towel, and then use compressed oil-free or inert gas.
Soaking the burner in nitric acid and using an ultrasonic bath effectively removes soft chemical deposits inside the slot. The removal of hard carbon deposits usually requires more significant physical effort.
If the width of the slot exceeds 0.47 mm (0.0185 in) for a nitrous-oxide/acetylene burner or 0.54 mm (0.021 in) for an air/acetylene burner, the burner cannot be refurbished and must be replaced with a new one.
The damage or corrosion on the internal burner surface and slot can be caused prolonged exposure to high acid concentration solutions and/or acid vapor, because often, after the analysis is completed the flame is immediately turned off. Then, small drops from the last sample/solution will remain on the internal burner surface.
In addition to the preceding cleaning procedure, the following extra step can improve burner life time: After the last sample has been completed and before turning off the flame, aspirate a blank or cleaning solution (2–5% HNO3) for 2–3 minutes. This will remove all excess of sample/standard solutions remaining on the burner surface in the form of small drops.
The burner is now ready to use.
Learn how to effectively maintain your Agilent Atomic Absorption Spectrometry System: Guidelines for Troubleshooting and Maintenance of AA Systems