RATIONALE A method for the determination of rare earth elements in carbonatite rocks by inductively coupled plasma mass spectrometry (ICP-MS) was developed. METHODS An alkaline rock, carbonatite, was submitted to ultrasound-assisted extraction (USAE) using an ultrasound bath, a cup horn system or an ultrasound probe. The main USAE parameters were evaluated, such as extraction time (1 to 30 min), extraction temperature (20 to 100°C) and ultrasound amplitude (10 to 100%). For ICP-MS, a desolvation system (APEX-Q) was used to reduce interference in lanthanide determination. To evaluate if the effect of ultrasound improved extraction, experiments were carried out using magnetic stirring (500 rpm) for comparison. RESULTS The temperature and ultrasound amplitude optimized for the method were 70°C and 40%, respectively, using dilute nitric acid (3% v/v). Quantitative analyte recoveries were obtained using an ultrasound bath (25 kHz/100 W) which allowed for the simultaneous extraction of twelve replicates. CONCLUSIONS All the results obtained with the use of ultrasound systems were better than those obtained with mechanical stirring. The extracts were suitable for ICP-MS analysis and the results were in agreement with those obtained by the reference method (using wet acid digestion). Based on the results, the use of USAE can be considered an alternative method for sample preparation of carbonatite rocks, under milder conditions, for further ICP-MS analysis.

中文翻译：

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一种超声辅助样品制备方法，用于电感耦合等离子体质谱法测定稀土元素。

原理建立了一种电感耦合等离子体质谱法（ICP-MS）测定碳酸盐岩中稀土元素的方法。方法使用超声浴，杯形喇叭系统或超声探头将碱性岩石碳酸盐岩进行超声辅助萃取（USAE）。评估了USAE的主要参数，例如提取时间（1至30分钟），提取温度（20至100°C）和超声振幅（10至100％）。对于ICP-MS，使用去溶剂化系统（APEX-Q）来减少镧系元素测定中的干扰。为了评估超声的提取效果是否得到改善，使用磁力搅拌（500 rpm）进行实验以进行比较。结果针对该方法优化的温度和超声幅度分别为70°C和40％，使用稀硝酸（3％v / v）。使用超声浴（25 kHz / 100 W）获得定量的分析物回收率，可同时提取十二个重复样品。结论使用超声系统获得的所有结果均优于通过机械搅拌获得的结果。提取物适用于ICP-MS分析，结果与参考方法（使用湿酸消解法）获得的结果一致。根据结果​​，可以认为使用USAE是在较温和的条件下制备碳酸盐岩样品以进行进一步ICP-MS分析的另一种方法。结论使用超声系统获得的所有结果均优于通过机械搅拌获得的结果。提取物适用于ICP-MS分析，结果与参考方法（使用湿酸消解法）获得的结果一致。根据结果​​，可以认为使用USAE是在较温和的条件下制备碳酸盐岩样品以进行进一步ICP-MS分析的另一种方法。结论使用超声系统获得的所有结果均优于通过机械搅拌获得的结果。提取物适用于ICP-MS分析，结果与参考方法（使用湿酸消解法）获得的结果一致。根据结果​​，可以认为使用USAE是在较温和的条件下制备碳酸盐岩样品以进行进一步ICP-MS分析的另一种方法。