| 微量磷灰石中磷酸根氧同位素分析方法 |
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| 引用本文： | 杜勇,朱园园,宋虎跃,王宇航,宋海军,邱海鸥,童金南.微量磷灰石中磷酸根氧同位素分析方法[J].地球科学,2019,44(2):456-462. |
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| 作者姓名： | 杜勇 朱园园 宋虎跃 王宇航 宋海军 邱海鸥 童金南 |
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| 作者单位： | 1.中国地质大学生物地质与环境地质国家重点实验室, 湖北武汉 430074 |
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| 基金项目： | 中国地质大学大型仪器设备改造项目DY-201617生物地质与环境地质国家重点实验室自主课题GBL11603国家自然基金项目41530104生物地质与环境地质国家重点实验室自主课题GKZ14Y663国家自然基金项目41661134047国家自然基金项目41402302 |
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| 摘 要： | 生物磷灰石壳体的磷酸根氧同位素组成是重建古温度理想指标之一，在古环境研究中具有重要意义.针对牙形石等磷灰石量极少的情况，稳定可靠的前处理方法是分析其δ18OPO4的重要保障，目前仅有少数国外实验室已建立了相关提取分析方法.结合这些方法的优缺点对分析步骤进行改进优化，建立了微量磷灰石的磷酸根氧同位素分析方法，通过硝酸消解磷灰石并除去非磷酸根氧，利用KF溶液沉淀法分离Ca2+，采用氨缓冲溶液形式调节pH，并加入AgNO3溶液以氨挥发法将PO43-转化成Ag3PO4结晶分离，气体稳定同位素质谱仪在线测定Ag3PO4氧同位素组成.结果表明，方法全流程未产生明显的氧同位素分馏，样品最低仅需0.2 mg，标准偏差小于0.2‰（1σ），与目前国际报道的分析精度一致.
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| 关 键 词： | 磷灰石 磷酸根氧同位素 分析方法 生物地球化学 |
| 收稿时间： | 2018-12-08 |
Analytical Method for δ18O of Phosphate in Trace Apatite |
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| Abstract: | The oxygen isotope composition of phosphate (δ18OPO4) in bioapatite plays a significant role in paleo-environmental research as one of the ideal proxies for paleo-temperature reconstruction. However, for trace bioapatite(e.g., conodonts), a reliable pre-treatment technology is quite important and difficult for its δ18OPO4 analysis, resulting in analytical technique established only in several overseas laboratories. Here we combine the advantages of those methods and present a protocol on the analysis of δ18OPO4 as Ag3PO4 for bioapatite of total sample size as small as 0.2 mg using a thermal conversion elemental analyzer (TC/EA) coupled to a continuous flow isotope ratio mass spectrometer (CF-IRMS) via a helium stream. Ag3PO4 is precipitated by NH3 buffer method after apatite being dissolved with nitric acid, Ca2+ being removed with KF solution and the solution being neutralized with ammonia buffer solution. The results indicate that analysis of δ18OPO4 maintains an external precision of ±0.2‰(1σ), meeting the international analytical standards. This method for analyzing δ18OPO4 of phosphate extracted from bioapatite is robust to be used to reconstruct paleo-temperature. |
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