Porteous N C, Walsh J N, Jarvis K E
Geology Department, Royal Holloway College, University of London, Egham, Surrey, UK.
Analyst. 1995 May;120(5):1397-400. doi: 10.1039/an9952001397.
Boron is present at low levels in groundwater and rainfall in the UK, ranging between 2 and 200 ng ml-1. A sensitive technique has been developed using inductively coupled plasma mass spectrometry (ICP-MS) to measure boron isotope ratios at low concentrations with a precision (Sr) of between 0.1 and 0.2%. Samples were evaporated to increase elemental boron concentrations to 200 ng ml-1 and interfering matrix elements were removed by an adapted cation-exchange separation procedure. The validity of measuring boron isotopic ratios by ICP-MS at this concentration level is discussed in relation the theoretical instrument precision attainable based on counting statistics. Using the developed procedure it is possible to use ICP-MS to establish a reliable database documenting the natural variation in boron isotope compositions in aquifers and rain water in the UK. Preliminary results demonstrate a trend in boron isotopic compositions with increasing boron concentration. The method may be used to evaluate possible levels of boron pollution from anthropogenic inputs into natural aqueous systems.
在英国，地下水中和降雨中的硼含量较低，范围在2至200纳克/毫升之间。已经开发出一种灵敏的技术，利用电感耦合等离子体质谱法（ICP-MS）在低浓度下测量硼同位素比率，其精密度（δ¹¹B）在0.1%至0.2%之间。将样品蒸发以提高元素硼浓度至200纳克/毫升，并通过改进的阳离子交换分离程序去除干扰基体元素。基于计数统计所达到的理论仪器精密度，讨论了在此浓度水平下用ICP-MS测量硼同位素比率的有效性。利用所开发的程序，有可能使用ICP-MS建立一个可靠的数据库，记录英国含水层和雨水中硼同位素组成的自然变化。初步结果表明，硼同位素组成随硼浓度增加呈现出一种趋势。该方法可用于评估人为输入到天然水系统中硼污染的可能水平。
