Field M P, Sherrell R M
Institute of Marine and Coastal Sciences, Rutgers University, 71 Dudley Road, New Brunswick, New Jersey 08901-8521.
Anal Chem. 1998 Nov 1;70(21):4480-6. doi: 10.1021/ac980455v.
A new method has been developed combining desolvating micronebulization with magnetic sector inductively coupled plasma mass spectrometry (ICPMS) for the analysis of all 14 stable rare earth elements (REEs) in small samples of marine particulate matter. Application is demonstrated for REEs in suspended particles from a deep ocean hydrothermal vent plume and a geological reference material. A 100-fold reduction in oxide formation, relative to standard nebulizer-spray chamber sample introduction, makes oxide interference correction negligible, even for samples that are very enriched in Ba and light REEs. Enriched isotopes for one light and one heavy REE ((145)Nd and (171)Yb) are used as both isotope dilution and internal standards, providing determination of all the REEs in one analysis. This standardization scheme eliminates the need for multimass drift correction used previously to achieve acceptable accuracy with external standardization techniques. Instead, the method exploits capabilities for accurate and precise determination of isotope ratios, a principal strength of ICPMS, and the mass-independent sensitivity of electric field scans on our double-focusing instrument. We demonstrate overall precision of ≤2% (1σ) and accuracy better than 6% for all the REEs (except Er = 8.7%), based on comparison to recommended values for USGS certified reference material BHVO-1 (basalt). This performance is similar to that obtained by full isotope dilution mass spectrometric techniques, but the new method is far simpler, requires 5 min sample(-)(1), and avoids interferences introduced by complex mixtures of enriched isotopes. Sensitivity of (1.2-1.4) × 10(6) counts s(-)(1) ppb(-)(1) and background intensities of 2-60 counts s(-)(1) provide excellent detection limits of 1-40 ppq, a 100-fold improvement on established ICPMS methods. The low sample introduction rate (100 μL min(-)(1)) allows unprecedented absolute detection limits of 1-20 fg.
已开发出一种新方法，将去溶剂化微雾化与磁扇形电感耦合等离子体质谱法（ICPMS）相结合，用于分析海洋颗粒物小样本中的所有14种稳定稀土元素（REE）。该方法已应用于深海热液喷口羽流中的悬浮颗粒以及一种地质参考物质中的稀土元素分析。与标准雾化器 - 喷雾室进样方式相比，氧化物形成减少了100倍，使得氧化物干扰校正可忽略不计，即使对于钡和轻稀土元素含量非常高的样本也是如此。一种轻稀土元素和一种重稀土元素（（145）Nd和（171）Yb）的富集同位素用作同位素稀释剂和内标，一次分析即可测定所有稀土元素。这种标准化方案无需使用先前为通过外标技术达到可接受精度而采用的多质量漂移校正。相反，该方法利用了ICPMS准确精确测定同位素比率的能力以及我们双聚焦仪器上电场扫描的质量无关灵敏度。基于与美国地质调查局认证参考物质BHVO - 1（玄武岩）推荐值的比较，我们证明所有稀土元素（除铒的相对标准偏差为8.7%外）的总体精密度≤2%（1σ），准确度优于6%。此性能与通过全同位素稀释质谱技术获得的性能相似，但新方法要简单得多，每样本只需5分钟，且避免了富集同位素复杂混合物引入的干扰。灵敏度为（1.2 - 1.4）×10（6）计数·秒（-1）·ppb（-1），背景强度为2 - 60计数·秒（-1），提供了1 - 40 ppq的出色检测限，比现有ICPMS方法提高了100倍。低进样速率（100 μL·分钟（-1））实现了前所未有的1 - 20 fg绝对检测限。
