Analytical Method for δ18O of Phosphate in Trace Apatite
Du Yong
Zhu Yunayuan
Song Huyue
Wang Yuhang
Song Haijun
Qiu Haiou
Tong Jinnan
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.
Keywords：bioapatiteoxygen isotope of phosphateanalytical methodbiogeochemistry
Publication Date：2019-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：7( 456-462 )