I'm operating a Thermo electronics FAAS for Si analysis. As soon as the flame is ignited(before changing to N2O acetylene flame, it gives a high orangish flame which is not usual. Can someone explain why it happens and how to overcome?
It could be residue of NaCl from a previous sample. When was the last time the burner was cleaned in dilute Nitric Acid?
Hello, Sakalya. Can I ask a few questions? Does this orangish flame last, or is it just for a short period of time? Does it occur with your Air -Acetylene flame and with your NO2-Acetylene flame? Does it occur if you don't have any solvent flowing through your flame? Knowing these things would be helpful for troubleshooting.
Of course cleaning is always a quick thing to try. Because contaminants are virtually always soluble salts (this depends on what you use your AAS for - but the salts got there in solution so they should be soluble) I always clean our burner with DI water. I would only use a weak oxidizing acid if the DI water didn't clean it properly.
You have Na residual in the flame system or in the aspirated liquid
Dear all, thank you for answering. Bruce Neagle Mahmoud Ghuniem We have not analysed Na before. The last time I tried to measure Si and used a 100ppm solution. Burner hasn't been cleaned for some time. May be aroun 100 samples.
Daniel King Yes it lasts for some time, actually I turned it off even before 1 minute thinking that it is harmful for the machine.It occurred in air acetylene flame. It occured when igniting the flame and DI water is running.
So, should I clean the burner and check?
Na can be in your sample matrix. A low pressure Acetylene tank can also have an orangish flame (from the Acetone?).
You might see what the flame looks like when you don't have liquid flowing into the system. This will help you to determine if the cause is coming from your tubing and sample inlet. If the flame looks fine without the water, then it's probably your water or tubing may need cleaned. If the the flame looks odd without the water, too, then it could be the burner or acetylene that has some contamination.
As I recall sand and glass are Sodium Silicate (probably with other stuff too!). You may find this in all your Si samples.
Dear Bruce Neagle and Daniel King , what I tried to measure was a 100ppm standard Si solution diluted from a commercial 1000ppm standard. Do you think Na is included in that too?
Flame looks the same with and without water running in the system. Acetylene is also a new tank, so I don't know if it is contaminated. as Bruce Neagle wonders, can the acetylene tank has low pressure, without a warning sign from the software? It displayed all gasses (air, acetylene and N2O) to be OK
But the burner, might be contaminated right?
Your Si standard solution should be fine. If there's a problem with the acetylene then nothing you do should alter that. It sounds likely that it's the burner. Definitely worth cleaning it and seeing if anything changes.
Dear all, I hope you are having a great day!
Today, I rechecked the instrument with only air acetylene flame. Flame was not that high and not that orangish.
First picture is without aspiring water, which is blue but with some yellow in the flame
Second is when aspiring water, with more yellow in the flame
Third picture is when we had no problem (one month ago).
Flame didn't get to that level yet. Do you think the problem is with tubing and spray chamber?
Talking about cleaning the burner head, it is not encouraged in my lab as it might affect sensitivity??
Can you please let me know your opinion after seeing the pictures?
It is possible that the burner in your spectrometer has a slightly soiled slot. The slot must be perfectly smooth on the inner surface. Then the measurements will be better reproducible and without drift sensitivity.
I tend to agree that it looks like the burner needs cleaned. I don't think you have anything to be anxious about, though. The burner just pops off, invert it and run DI water through it, and spray across the top surface, and run the straight edge metal tool (that came with the burning) through the slot a few times. Dry it, light it up, and see how it looks. Best of luck.
Outside burner cleaning, try to purify the sample. Elements in impure samples complement each and give funny flame colours.
Red/Yellow Flame = Incomplete Combustion
The yellow color is due to incandescence of very fine soot particles that are produced in the flame.
Cleaning the burner and controlling the gas/air ratio would fix the problem
Hello!
Sorry for the long due update. Thank you for all your opinions. As most of you suggested, cleaning of the slot resolved the problem. There was a layer of carbon on the slot. so It has caused incomplete combustion. I'm glad it worked out and I so much appreciate your support.
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