偏硼酸锂碱熔-电感耦合等离子体质谱法同时测定海洋沉积物中48种元素

海洋沉积物常用的分析方法如敞开消解或高压密闭消解结合电感耦合等离子体质谱(ICP-MS)或电感耦合等离子体发射光谱(ICP-OES)测定,粉末压片或熔片结合X射线荧光光谱法(XRF)测定,分别存在消解不完全、速度慢、检出限高等缺点,导致样品前处理效率低、待测元素少。针对上述问题,本文采用偏硼酸锂为熔剂分解样品,5%硝酸浸取,用ICP-MS法进行测定,建立了一种快速分析海洋沉积物中48种元素的方法。使用海洋沉积物国家标准物质作为高点绘制标准工作曲线,确定了助熔剂偏硼酸锂用量、稀释倍数、各待测元素的分析同位素及内标元素、仪器测定模式及个别元素的干扰校正方程等,得到最佳分解条件及测定条件。结果表明:由于高温损失,P、As、Se、Cd、Hg等元素无法得到准确结果,可改用微波消解等方式前处理后再进行测定;Cu、Zn、Cr、Ni、Co等共计48种元素使用本法均能得到准确结果,各元素方法精密度(RSD)均小于9.7%。本方法应用于分析海洋沉积物国家标准物质GBW07333、GBW07314、GBW07335、GBW07336,测定值和认定值相符;分析海洋沉积物实际样品,各元素加标回收率介于83.6%~118.6%。本方法可测定元素多,极大提高了分析效率,适合大批量样品分析。

Simultaneous Determination of 48 Elements in Marine Sediments by ICP-MS with Lithium Metaborate Fusion

BACKGROUND: The common analysis methods of marine sediments, such as open digestion or high-pressure closed digestion combined with inductively coupled plasma-mass spectrometry (ICP-MS) or inductively coupled plasma-optical emission spectroscopy (ICP-OES) determination, and pressed powder pellet or fusion tablets combined with XRF determination, have a low efficiency of sample pretreatment and less detectable elements. The disadvantages of incomplete digestion, slow speed and high detection limit contribute to the inefficiency of the method.
OBJECTIVES: To develop a rapid method for the determination of 48 elements in marine sediments by ICP-MS.
METHODS: Lithium metaborate was used as a flux to decompose the sample. The obtained sample was leached with 5% nitric acid and determined by ICP-MS. An analytical method for the rapid determination of 48 elements in marine sediments was established. Using the national standard references materials of marine sediment as the high point, the standard working curve was drawn. The amount of flux LiBO₂, dilution ratio, analytical isotope and internal standard elements of each element to be measured, instrument measurement mode and interference correction equation of individual elements were determined, an optimal decomposition conditions and measurement conditions were obtained.
RESULTS: The results showed that the accurate results of P, As, Se, Cd, Hg cannot be obtained due to high temperature loss, yet microwave digestion or other methods could be used for pretreatment to avoid loss before determination. The accurate results of 48 elements may be obtained by this method, the relative standard deviation (RSD) of each element was less than 9.7%. The measured values of the national standard references of marine sediments GBW07333, GBW07314, GBW07335 and GBW07336 were consistent with the certified values. The recoveries of each element in marine sediment samples ranged from 83.6% to 118.6%.
CONCLUSIONS: This method greatly improves the analysis efficiency, and can analyze more elements, suitable for the analysis of large numbers of samples.