For LSC have a look at chapter 8 from the attached booklet

Radu's suggestion is a good one. Also, if you want to talk with someone with experience--I'd contact Svetlana Nour or Jerome (Jerry) LaRosa at NIST. Both make and measure radionuclide-doped natural matrix standards and performance testing (PT) materials. Just Google their names and "NIST" and you should be able to get their contact info. If they haven't experience in what you are trying to do, they should know who does.

Dear Radu,

Thank you so much for your help and your valuable booklet.

My big problem is how to extract total 226Ra from the soil (soil sample preparation) for counting by LSC, now. I was looking for a simple and rapid method. I have found some papers in this field but all of them are time consuming and  complicated. My field study is soil science (agriculture) and don't have any expertise in this area.This subject is one the section of my PhD program. 

Sincerely,

Sareh.

I see... well this is a matter of radiochemistry and I am afraid there is no simple solution for that. But I cannot help you with that, it is out of my field of expertise.

Dear M. A. Tyra,

Thank you so much for your help and guidance.

I will contact with guys that you have introduced in this field.

Hope i could find anyone to help me solve this problem.

Thank you again.

sincerely,

sareh.

I attach a rapid LSC method for 226Ra by LSC, and a sequential extraction application for 210Pb. Good luck!

Hello Dear Joan -Albert,

I  appreciate so much for your valuable papers.

They were so useful for me. I want to ask you some questions about your paper "in the section of 210Pb sequential extraction Method 2", you have mentioned that the supernatant  were evaporated on a hot plate and the 210Pb analysis of the dry residues were performed following the methodology described in sect. 2.3.2.

Where is this section (2.3.2) in the text?

Should i use internal tracer to each supernatant for 226Ra, too?

What was the speed of centrifuge and how long ?

And did you use any filter paper for filtering the supernatant in each fraction? 

Thank you so much,again.

Dear Colleaque! We used Geiger counter to put Ra containing medium

  inside and measure radon decay product alfa-particles /Best regards

See our publications  Borexino experiment

Try ASTM standard D5072-98 extraction of Rn into mineral oil based cocktail. Combined with portable Hidex Triathler can be very efficient screening tool.

You could read this document (IAEA):

https://nucleus.iaea.org/rpst/referenceproducts/analytical_methods/aq-19.pdf

Bets Regards