Measurements of Natural Carbonate Rare Earth Elements in Femtogram Quantities by Inductive Coupled Plasma Sector Field Mass Spectrometry

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• 作者：Chuan-Chou Shen ; Chung-Che Wu ; Yi Liu ; Jimin Yu ; Ching-Chih Chang ; Doan Dinh Lam ; Chien-Ju Chou ; Li Lo ; Kuo-Yen Wei
• 刊名：Analytical Chemistry
• 出版年：2011
• 出版时间：September 1, 2011
• 年：2011
• 卷：83
• 期：17
• 页码：6842-6848
• 全文大小：983K
• 年卷期：v.83,no.17(September 1, 2011)
• ISSN：1520-6882

文摘

A rapid and precise standard-bracketing method has been developed for measuring femtogram quantity rare earth element (REE) levels in natural carbonate samples by inductively coupled plasma sector field mass spectrometry that does not require chemical separation steps. A desolvation nebulization system was used to effectively reduce polyatomic interference and enhance sensitivity. REE/Ca ratios are calculated directly from the intensities of the ion beams of ⁴⁶Ca, ¹³⁹La, ¹⁴⁰Ce, ¹⁴¹Pr, ¹⁴⁶Nd, ¹⁴⁷Sm, ¹⁵³Eu, ¹⁶⁰Gd, ¹⁵⁹Tb, ¹⁶³Dy, ¹⁶⁵Ho, ¹⁶⁶Er, ¹⁶⁹Tm, ¹⁷²Yb, and ¹⁷⁵Lu using external matrix-matched synthetic standards to correct for instrumental ratio drifting and mass discrimination. A routine measurement time of 3 min is typical for one sample containing 20鈥?0 ppm Ca. Replicate measurements made on natural coral and foraminiferal samples with REE/Ca ratios of 2鈥?42 nmol/mol show that external precisions of 1.9鈥?.5% (2 RSD) can be achieved with only 10鈥?000 fg of REEs in 10鈥?0 渭g of carbonate. We show that different sources for monthly resolved coral ultratrace REE variability can be distinguished using this method. For natural slow growth-rate carbonate materials, such as sclerosponges, tufa, and speleothems, the high sample throughput, high precision, and high temporal resolution REE records that can be produced with this procedure have the potential to provide valuable time-series records to advance our understanding of paleoclimatic and paleoenvironmental dynamics on different time scales.