How to prepare and analyze asbestos by ICP-OES

I have another challenging preparation question for you. I’ve been given a sample of asbestos to prepare and analyze by ICP-OES. I’ve tried two different fusions at 1100C. A sodium carbonate one and a sodium peroxide one and neither have worked. Any help would be much appreciated.

Asbestos is a hydrous magnesium silicate formula Mg3Si2O5(OH)4. The first step is to make sure the sample is a fine powder. When mixed with sodium carbonate at a 20:1 ratio it should be opened out at 1000 deg C using a Pt dish/muffle furnace. Let it go for ~ 15 minutes. Dissolve the fuseate in 10% v/v HCl making sure to keep the concentration of the Si < 10 mg/L and measure the same day. Do not try adding HF. This preparation is tricky in that the silicic acid will be soluble and stable at low concentrations for a while but will slowly polymerize (takes a good while). Normally the fuseate would be taken up in nitric/HF but this does not work for this sample (if the nitric/HF ratio is 20:1 it will go into solution but then will drop MgF2 when diluted with water (I have used EDTA/TEA/TETA/Boric acid mixture to keep in solution but this is more work than the simple fusion/dilution with HCl). It is also important that the sample be finely ground and the fusion allowed to go for a few minutes.

Serving you in chemistry,

Paul R. Gaines, Ph.D.
CEO of Inorganic Ventures & Fellow Chemist

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