Dear Hadi Maghsoudiganjeh ,

Na ionization energy is too low, therefore, ICP, AAS have very high temperatures, so they are not adequate. XRF will bring some problems due to low wt%, as stated.

Flame photometry would give you the best result.

There are were chemistry methods, nevertheless, the problem would be the sensitivity at low concentrations.

Best regards,

WNM

Hi!

If results are needed almost immediately, then only with the XRF technique. Another thing is the accuracy of these results and this depends mainly on the accuracy of the calibration values ​​in the calibration samples. The remaining techniques are solution techniques, then they are the most accurate. In terms of possible measurement precision and detectability, F-AAS, F-AES, ICP-AES are similar. But it also depends on what instruments are at your disposal and who will be taking the measurements. Measurements using either of these techniques require matrix calibration solutions, i.e. with an aluminum concentration similar to the sample solutions. The method of transferring the samples into solution is also crucial. For example, whether to use hydrochloric acid alone, possibly with the addition of hydrogen peroxide, or also with the addition of fluorides, but this complicates the spectrometric measurements, because fluoride-resistant equipment must be used. The first two techniques are single-element techniques. So, if you need data on other impurity elements as well, it's rather just ICP-AES. It would be best to use the XRF technique and its derivatives, eg TXRF, as much as possible. It would be very advisable for you to get in touch with laboratories that specialize in the analysis of aluminum and its alloys.

ZJ

As always, the question has to be asked: What do you mean by "best"?

• Fastest?
• Cheapest?
• Quickest preparation?
• Most accurate?
• Least prone to error?
• Least waste?

My expertise is with ICP, so can't comment so much on the other techniques. XRF is perhaps what you are looking for, but at 1000ppm, in an Al matrix, Na might be hard to detect accurately. The grain size of the powder can make a significant difference, so there may be some method development you need to work on at first.

Perhaps a simple flame photometer would be the most practical solution as Wagner Da Nova Mussel suggests. but not because ICP is not adequate for Na analysis: Na is easily ionised and therefore readily detected by ICP instruments. An Al matrix would potentially create quite a few spectral issues for ICP analysis, but there is always some chemistry that can solve(!) the problem.

Dear Hadi,

I agree with both Wagner Da Noca, and Mathew Wheal for suggesting the use of Flame Photometry.

Good Luck to You.

Thanks everybody for your great comments.

AAS and ICP-MS are good method for determining the sodium.

Dear Hadi

At the concentration levels you are dealing with (0.1% Na), sensitivity would hardly be an issue. First, you have to define your problem: Are you looking for Na impurities (a) coated on the surface of the Alumina particles, or (b) Na impurities embedded inside the alumina matrix (total impurities).

If it is (a), which I suspect is the case, then a simple acid leaching (without total dissolution) may be sufficient. However, if it is (b), you need to dissolve alumina matrix, which is not easy. In this case, commonly used dissolution in NaOH is out of the question, as Na is your analyte. You may consider following options (among others) for total dissolution:

- Phosphoric acid

- high-purity grade KOH

- Citric acid

Following dissolution, you may dilute the solution as needed to match the optimum calibration range (and acidity) of the technique available to you. Any of the techniques, ICP-MS, ICP-ES, FAA, Photmetry, etc.. will do the job.

Best wishes!

Nimal

Thanks Nimal

Please look at the following below links which may help you in your analysis:

https://nvlpubs.nist.gov/nistpubs/jres/34/jresv34n2p129_A1b.pdf

https://www.osti.gov/servlets/purl/4335618

https://patents.google.com/patent/US5700652A/en

Thanks

Dear Friend Isam Eldin Hussein Elgailani!

Your links are for documents that are not applicable for metallic aluminum analyzes or for measurement techniques no longer used today.

ZJ