al-Masri M S, Blackburn R
Department of Chemistry and Applied Chemistry, University of Salford, UK.
Sci Total Environ. 1995 Dec 1;173-174:53-9. doi: 10.1016/0048-9697(95)04747-6.
A Cerenkov based method has been developed for the determination of 226Ra via its beta-emitting daughters, 214Bi and 214Pb. Radium isotopes are separated from interfering elements by coprecipitation on barium sulphate. The precipitate is dissolved in an alkaline solution of EDTA and the Cerenkov signal produced by the build-up of daughter beta activities is counted after 25 days using the tritium channel of a liquid scintillation counter. To correct for any contribution from the daughters of the radium isotopes 224Ra and 228Ra present in the sample, the barium(radium) sulphate is reprecipitated, dissolved in EDTA, and counted 2 days later. Using this procedure, 228Ra can be determined in the same sample. Cerenkov counting efficiency was found to be 77.25%. A lower limit of detection of 17.4 mBq l-1 (based on 3 sigma of the background with 500 min counting time) was achieved. Any liquid scintillation counter can be used. Chemical recoveries in the range 75-95% were determined gravimetrically. Data from both artificial spiked samples and natural samples are presented.
已开发出一种基于切伦科夫效应的方法，用于通过其β发射子体214Bi和214Pb测定226Ra。镭同位素通过在硫酸钡上共沉淀与干扰元素分离。沉淀物溶解在EDTA碱性溶液中，25天后，使用液体闪烁计数器的氚通道对由子体β活度积累产生的切伦科夫信号进行计数。为校正样品中存在的镭同位素224Ra和228Ra子体的任何贡献，将硫酸钡（镭）重新沉淀，溶解在EDTA中，并在2天后进行计数。使用此程序，可以在同一样品中测定228Ra。发现切伦科夫计数效率为77.25%。实现了17.4 mBq l-1的检测下限（基于500分钟计数时间的背景3σ）。任何液体闪烁计数器均可使用。通过重量法测定化学回收率在75-95%范围内。给出了人工加标样品和天然样品的数据。
