Sakalya, you can't use dry ashing technique. When you use it, Silicon convert insoluble Silicon Dioxide. You should use wet digestion or microwave digestion with HF acid.Then you can get Silicon soluble form and can analyse using AAS or other method.

Dear Sakalya,

In addition to Herath, if you hope to analyse Si by wet digestion with HF, make sure that you have to use Si free containers such AsTeflon for the digestion.

Piyal

I assume that it is about high silicon content, at the level of even a few%. If you perform the incineration of a plant sample in a vessel made of platinum, then use fluoric acid (and then excess boric acid) or use fluoroboric acid from the beginning and after adding a small amount of hydrochloric acid and diluting with water, the silicon will be in a solution suitable for FAAS measurements. The quality of measurements of silicon concentrations with the help of FAAS will mainly depend on the stability of the flows of both gases - acetylene and nitrous oxide, and the smoothness of the internal surface of the burner slot. Also, the method of preparation of calibration solutions is important, preferably as a source of silicon use commercially available solution. You can find a detailed recipe in ancient chemical analysis textbooks, such as M.Pinta, "Atomic Absorption Spectrometry. Applications in Chemical Analysis", 1974 (?).

Probably, however, it will be easier to use modern wet method and ICP-AES measurements.

ZJ

To add to Dr. Jonca's excellent answer you should use the method of known addition since the matrix is quite complex following fluoborate digestion. I agree as to the ease; ICP is much easier and you can use conventional digestions with a touch of HF added.

Dear all, thank you very much for all your answers. I understand that wet digestion and ICP would be much easier approach, but as is not available in my lab, I was focusing more on dry ashing and FAAS. I was able to get a rough understanding about the concept, thanks to all your answers. I will read more on the topic.

Dear Zbigniew Jonca,

I tried to find the text you mentioned; "M.Pinta, "Atomic Absorption Spectrometry. Applications in Chemical Analysis", 1974 " but couldn't find. If you could provide a link, I'm extremely greatful. Thanks

Dear Sakalya Rajapakse,

AOAC method given in this link may be useful for your analysis.

Piyal Aravinna,

https://student.cc.uoc.gr/uploadFiles/184-%CE%A7%CE%97%CE%9C-068/Compositional%20Analysis%20of%20foods%20-%20Food%20Analysis%20-%20S.S.%20Nielsen.pdf

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A lot of important information on how to perform the analysis of plant materials, starting from the incineration of several gram test quantities, you will find in: - Maurice Pinta (et al.) "Spectrometrie d'Absorption Atomique. Applications a L'Analyze Chimique", Masson Editeurs, Paris 1971. Application of HF + H3BO3, in: - W.J.Price "Analytical Atomic Absorption Spectrometry", Heyden & Son, London 1972. There are a lot of newer and quite contemporary items of professional literature on the subject of preparing plant samples for spectrometric measurements. If you do not have the possibility to analyze such samples, as dry mineralization and FAAS measurements, you have very limited possibilities of action. I do not know what I could advise you, except that you can find a lot of useful tips in older publications, also in previous and current publications of the standards of various state services and public institutions. Long time ago, I made such analyzes of plant samples, but after wet mineralization with nitric acid (with the addition of perchloric acid), but also specialist equipment is needed for this. It is necessary to invest in modern laboratory equipment and measuring instruments, otherwise our work is more difficult and less effective, than it could be. Greetings.

I seem to recall (long ago) the AOAC had a method for Silicon in plants.

Hi!

Maybe this book will help you:

http://lux.e-reading.bz/bookreader.php/136339/SL1248_CH23.pdf

ZJ

In this book there are links to more recent work on the determination of silicon:

https://www.google.pl/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=2ahUKEwjd6p3Ct8reAhVQ3aQKHbmXDQQQFjAAegQICRAC&url=https%3A%2F%2Fwww.springer.com%2Fcda%2Fcontent%2Fdocument%2Fcda_downloaddocument%2F9783319229294-c2.pdf%3FSGWID%3D0-0-45-1544438-p177646737&usg=AOvVaw2qQ9BmiTVKRKuLvM0mbzan

Dear A. G. Piyal Aravinna , Zbigniew Jońca , Bruce Neagle , Thank you very much for the links. I will go through them.

Recently, the book "Microwave-Assisted Sample Preparation for Trace Element Determination" appeared. It is a very good introduction and a guide to this issue. Just in case you do not have access to it, I attach the file. Greetings.