多接收电感耦合等离子体质谱仪测定沉积物中Cu和Zn同位素

本文介绍了海洋沉积物中Cu和Zn同位素的化学预处理及测定方法，报道了冲绳海槽20件表层沉积物和5件柱状沉积物样品的Cu和Zn同位素组成。采用大孔径阴离子交换树脂AG MP-1M，分别以8.2 mol/L HCl+0.01%HF+0.001%H₂O₂、2 mol/L HCl+0.001%H₂O₂和0.5 mol/L HNO₃作为淋洗液，能有效分离海洋沉积物中的基质元素和Cu、Zn元素，且Cu和Zn的回收率均接近100%。以内标法和标准−样品−标准法联合校正多接收电感耦合等离子体质谱仪的质量歧视，δ⁶⁵Cu和δ⁶⁶Zn的分析精度分别为0.11‰和0.09‰（2SD）。冲绳海槽表层沉积物δ⁶⁶Zn分布范围为0.07‰～0.67‰，δ⁶⁶Zn平均值为0.31‰±0.32‰（2SD）；δ⁶⁵Cu的分布范围为−2.26‰～−0.52‰，δ⁶⁵Cu平均值为−1.21‰±0.55‰（2SD）。表层沉积物δ⁶⁶Zn和δ⁶⁵Cu分布范围较大，柱状沉积物样品δ⁶⁶Zn和δ⁶⁵Cu值随深度存在较显著变化。

Determination of Cu and Zn isotopes in sediments by multi-collector inductively coupled plasma mass spectrometer

We presented an optimized and purification procedure as well as an analytical method for Cu and Zn isotopes measurement in marine sediments. We reported Cu and Zn isotope of 5 samples in a sediment cores and 20 surface sediment samples in the northern and southern Okinawa Trough. Anion exchange resin (AG MP-1M) was applied to separate matrix elements of sediment samples from Cu, Fe and Zn using 8.2 mol/L HCl+0.01% HF+0.001% H2O2, 2 mol/L HCl+0.001% H2O2 and 0.5 mol/L HNO3 as eluents. The recoveries of Cu and Zn were both close to 100%. Cu and Zn isotopes were measured on a Nu Plasma multi-collector inductively coupled plasma mass spectrometer (MC-ICP-MS). Instrumental mass bias was corrected using a combination of sample-standard bracketing and internal spiking. The long-term reproducibilities were 0.11‰ (2SD) for Cu isotopes and 0.09‰ (2SD) for Zn isotopes. The δ66Zn of surface sediments varies from 0.07‰ to 0.67‰, with an average of 0.31‰ ± 0.32‰ (2SD); the δ65Cu of surface sediments ranges from −2.26‰ to −0.52‰, with an average of −1.21‰ ± 0.55‰ (2SD). The results show that Cu and Zn isotopes of surface sediments in the Okinawa Trough varies widely, meanwhile, Cu and Zn isotopes in sediment core varies with depth.