Determination of radium-226 microimpurities by radon-222 in liquid organometallic compounds

A method for natural radium-226 microimpurity determination in liquid organometallic compounds, based on the measurement of internal filling of radon-222, extracted from the substance investigated by helium flow, using low-background proportional counter, has been developed. Radium mass determination limit and the lower boundary of the mass determined constituted 2.3x10-16 and 7.3x10-16 g respectively for four measurements of sample and background. Under the conditions when the sample mass is 500 g radium content of 4.8x10-19 g/g can be determined in the determination limit with relative standard deviation 0.33. On the lower boundary of radium mass determined the relative error of measurement equals 0.16 at fiducial proability 0.9. The content of radium - 226 in tetraethyllead, tripropylaluminium, diethylmercury, commercial - grade mercury and mercury produced from diethylmercury is measured