IR Laser Extraction Technique Applied to Oxygen Isotope Analysis of Small Biogenic Silica Samples

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• 作者：Julien Crespin ; Anne Alexandre ; Florence Sylvestre ; Corinne Sonzogni ; Christine Paill&egrave ; s ; Vincent Garreta
• 刊名：Analytical Chemistry
• 出版年：2008
• 出版时间：April 1, 2008
• 年：2008
• 卷：80
• 期：7
• 页码：2372 - 2378
• 全文大小：102K
• 年卷期：v.80,no.7(April 1, 2008)
• ISSN：1520-6882

文摘

An IR-laser fluorination technique is reported here foranalyzing the oxygen isotope composition (ages/gifchars/delta.gif" BORDER=0 >¹⁸O) of microscopic biogenic silica grains (phytoliths and diatoms).Performed after a controlled isotopic exchanged (CIE)procedure, the laser fluorination technique that allows oneto visually check the success of the fluorination reactionis faster than the conventional fluorination technique andallows analyzing ages/gifchars/delta.gif" BORDER=0 >¹⁸O of small to minute samples (1.6-0.3 mg) as required for high-resolution paleoenvironmental reconstructions. The long-term reproducibility achievedwith the IR laser-heating fluorination/O₂ ages/gifchars/delta.gif" BORDER=0 >¹⁸O analysis islower than or equal to ±0.26” (1 SD; n = 99) forphytoliths and ±0.17” (1 SD; n = 47) for diatoms. Whenseveral CIE are taken into account in the SD calculation,the resulting reproducibility is lower than or equal to±0.51” for phytoliths (1 SD; n = 99; CIE > 5) and±0.54” (1 SD; n = 47; CIE = 13) for diatoms. Aminimum reproducibility of ±0.5” leads to an estimateduncertainty on ages/gifchars/delta.gif" BORDER=0 >¹⁸O_silica close to ±0.5”. Resulting uncertainties on reconstructed temperature and ages/gifchars/delta.gif" BORDER=0 >¹⁸O_formingwater are, respectively, ±2ages/entities/deg.gif">C and ±0.5” and fit in theprecisions required for intertropical paleoenvironmentalreconstructions. Several methodological points such asoptimal extraction protocols and the necessity or not ofperforming two CIE prior to oxygen extraction are assessed.