Dear Bassel,

I suggest you read the work published by the GEMAS group on the concentration of elements in agricultural and grazing soil, among which Albanese et al., 2015, "GEMAS: Cobalt, Cr, Cu and Ni distribution in agricultural and grazing land soil of Europe", Journal of Geochemical Exploration, vol. 154, pp. 81-93.

Alessandro

Dear Alessandro, thanks for your suggestion. In this work they used WD-XRF which is, unfortunately, not available to me. the second choice "Aqua regia" which is not suitable to my samples since it is unable to completely dissolve the siliceous materials in soil.

Aqua regia + HF should work, as well as HNO3 + H2O2 + HF

This will help you:

Article Wet digestion methods

Kind regards,

Michał

Agree with Michal Filipiak. Hydrofluoric acid should do the job. If your sample has carbonate and oxides phase, then you may also need aqua-regia. Extra care should be taken if you are using this strong acids such as gloves, buddy system, special fume hood, and the use of teflon/HDPE vials.

Please have a look at enclosed article:

Article Digestion Methods for Total Heavy Metals in Sediments and Soils

Please have a look at enclosed link:

http://www.cengage.com/resource_uploads/downloads/0495558281_371363.pdf

Thank you all for valuable suggestions

Years back I digested sand samples for the glass industry. Sand was ground very fine using an Agate Mortar Pestle. Add 0.1 g to a 30 ml Platinum beaker and fill with HF. Boil to dryness. Perhaps you can determine Silica by change in weight with, perhaps using a pre-carbonate determination to account for any carbonates(?). Memory is a bit sketchy but would fuse using LiCarbonate and Na-borate mix ((?) making a glass. Heat over bunsen burner and roll the glass bead produced around until all was fused. Then would dissolve the glass using dilute HCl. Test using AA (now it would be ICP.).

Our group is facing studies on the origin of As in groundwaters and in order to identify the provision source of natural arsenic we applied mineralogical analyses together with studies of total content of macro and oligoelements. In our case we preferred total content analysis without digestion of the solid phase and applied Instrumental Neutron Activation Analysis (INAA) to quantify elements in soils and sediments. The samples were processed in ACTLABS (Canada) and you may have information of the content of a pool of 40 macro and microelements. Hope this information helps you.