Preparation of Graphite Targets from Small Marine Samples for AMS Radiocarbon Measurements
| Autor: | Pavel P. Povinec, A. J. Timothy Jull, Laval Liong Wee Kwong |
|---|---|
| Rok vydání: | 2004 |
| Předmět: |
010506 paleontology
Archeology 060102 archaeology Analytical chemistry chemistry.chemical_element Hydrochloric acid 06 humanities and the arts 01 natural sciences Nitrogen chemistry.chemical_compound chemistry General Earth and Planetary Sciences Gravimetric analysis 0601 history and archaeology Sample preparation Seawater Graphite Carbon 0105 earth and related environmental sciences Accelerator mass spectrometry |
| Zdroj: | Radiocarbon. 46:133-139 |
| ISSN: | 1945-5755 0033-8222 |
| DOI: | 10.1017/s0033822200039448 |
| Popis: | A vacuum sample processing line was set up and methods were developed for the determination of radiocarbon in small-volume seawater and biota samples. Seawater samples (500 mL per borosilicate glass bottle and poisoned with HgCl2) were acidified with 5 mL concentrated hydrochloric acid. Pure N2 was used as a carrier gas to strip CO2 from the samples for 10 min in a circulation mode. After purification through several water traps, the CO2 was isolated cryogenically. Using Na2CO3 standard solutions, recovery yields were calculated superior to 95 ± 5%. Freeze-dried marine biota samples were thoroughly mixed with Cu(II)O and combusted at 900°. The CO2 was purified by passing through Ag wool and Cu granules at 450° before reduction to graphite. Finally, graphite was synthesized using Zn dust heated to 450° in the presence of an Fe catalyst at 550°. Although this method takes about 8 hr (synthesis done overnight), the advantage is that no water vapor by-product is formed to hinder the reaction. The graphite yields, measured both by gravimetric methods and by pressure readings, were 95 ± 5%. Accelerator mass spectrometry (AMS) measurements were carried out at the NSF-Arizona AMS Facility. Results for water samples from the northwest Pacific Ocean are reported which are in agreement with data reported elsewhere. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|