Selection criteria for the measurement of Radium-226 in environmental samples

Radium-226 is routinely analysed in variety of environmental samples for many investigation and specific studies like dating sediments, water quality measurements, estimation of age of fish etc. Radium-226 is a α-emitters which has the half life of 1620 years. Alpha spectrometry and high resolution gamma spectrometry are some available techniques for the measurement of 226Ra. The properties of each technique are studied. Each technique has different background levels, geometric efficiency, preparation procedure and recoveries of 226Ra. This gives wide range of options with some restrictions imposed on sample size and activity. The paper discusses the selection criteria, optimum procedure and its dependency on sensitivity, precision and lower limit of detection of each technique. The process of method selection is illustrated here with reference to sediments. (author)