甲基膦酸二甲庚酯(P_(350))色层分离-α谱测量^(234)U/^(238)U和^(230)Th/^(232)Th的活度比

A METHOD USING DI-(1-METHYLHEPTYL)METHYL-PHOSPHATE CHROMATOGRAPHIC SEPARATION FOR MEASURING THE ACTIVITY RATIOS OF ^(234)U/^(238)U AND ^(230)Th/^(232)Th BY ALPHA- SPECTROMETR Y

一、引言 放射性铀、钍同位素在环保领域、水文地质中判断找矿远景,考古中测定古生物的年代得到广泛应用。 对铀、钍与其他干扰元素分离以及铀、钍互相分离,一般方法较复杂,需对铀、钍进行多次纯化。本文采用大孔型树脂X-5(聚二乙烯苯)为支持体,用水溶性小、对铀、钍分离效果好的P_(350)为萃取色层的固定相。将分离后的铀、钍分别电沉积制备成无载体的α面源,用α谱仪测定^(234)U/^(238)U,^(230)Th/^(232)Th的同位素活度比值。 本分离体系对高铀低钍、高钍低铀以及铁含量高的样品,均能得到满意的结果。本方法测定下限水样为1—2μg/1,固体样为5μg/g。10μg以上的铀、钍测定误差为±5％。

After ammonium hydroxide is added into 5-10 litres of an aqueous sample containing ferric chloride as carrier, uranium and thorium are concentrated by coprecipitation with ferric hydroxide.The precipitate is dissolved in 20% nitric acid and 2% tartaric acid.The solid samples are dissolved with mixed ammonium salt and adjusted to the same acidity.The uranium and thorium are separated and purified on the di- (l-me'thyiheptyi) methylphosphate (com-merical name p350) -macroporous resin column.The purified samples are eleet-rodeposited on stainless steel disk and determined by alpha-spectrometry.This method can be used for determination of high content iron samples and high level uranium-low level 'thorium or high level thorium-low level uranium samples,The detection limit obtained from 5 litres of aqueous sample is 1-2μg/l, whereas that of solid samples is 5μg/g.