CAJ | 학술논문

建立了应用多接收电感耦合等离子体质谱仪( MC-ICP-MS)测定稳定硅同位素比值的仪器分析方法。在干等离子体、中分辨率条件下,硅同位素高质量端受到C、N、O、H等元素形成的多原子离子的干扰。样品气流量对Si的灵敏度稳定性有重要影响,并且样品气流量增加会导致14 N16 O的强度增大。中分辨率条件下,低质量数端δ29 Si和δ30 Si在约9 milli-amu的质量范围内保持稳定,精度优于0.04‰(1σ)。采用“标准-样品”交叉法正校质量歧视时,为避免浓度效应对硅同位素测试的影响,要求标准和样品之间硅浓度差异低于20％。溶液酸度和Cl基体含量不会对同位素测量造成显著影响。通过优化数据采集参数,29 Si/28 Si和30 Si/28 Si的内精度(1σ)可达到8 ppm 以内。标准物质长期分析结果显示,δ29 Si 和δ30 Si 的长期稳定性可达到0.06‰~0.10‰(2σ,n=20),标准物质GBW04421和GBW04422的测量值与推荐值吻合,表明本方法精确可靠。对淡水(河水、湖水)、半咸水、海水的分析结果表明,应用硅同位素可以示踪天然水体中硅的生物地球化学过程。
건립료응용다접수전감우합등리자체질보의( MC-ICP-MS)측정은정규동위소비치적의기분석방법。재간등리자체、중분변솔조건하,규동위소고질량단수도C、N、O、H등원소형성적다원자리자적간우。양품기류량대Si적령민도은정성유중요영향,병차양품기류량증가회도치14 N16 O적강도증대。중분변솔조건하,저질량수단δ29 Si화δ30 Si재약9 milli-amu적질량범위내보지은정,정도우우0.04‰(1σ)。채용“표준-양품”교차법정교질량기시시,위피면농도효응대규동위소측시적영향,요구표준화양품지간규농도차이저우20％。용액산도화Cl기체함량불회대동위소측량조성현저영향。통과우화수거채집삼수,29 Si/28 Si화30 Si/28 Si적내정도(1σ)가체도8 ppm 이내。표준물질장기분석결과현시,δ29 Si 화δ30 Si 적장기은정성가체도0.06‰~0.10‰(2σ,n=20),표준물질GBW04421화GBW04422적측량치여추천치문합,표명본방법정학가고。대담수(하수、호수)、반함수、해수적분석결과표명,응용규동위소가이시종천연수체중규적생물지구화학과정。
An instrumental analysis method for the determination of stable silicon isotope ratio using multi-collector inductively coupled plasma mass spectrometry ( MC-ICP-MS) was established. In dry plasma mode, silicon isotopes suffered from the spectrum polyatomic interferences of C, N, O, H at medium resolution. The sample gas flow had significant effect on the silicon sensitivity and signal stability. Besides, higher sample gas flow lead to higher production of 14N16O. Consistent δ29Si and δ30Si within 0. 04‰ (1σ) could be obtained over a mass range of ca. 9 milli-amu at the lower mass side of silicon at medium resolution. The analyte concentrations of the sample and reference material were matched within 20% to avoid concentration effect on the determination of silicon isotopes using standard-sample-bracketing correction method. The measurements were not sensitive to the acid molarity and Cl matrix. An internal precision of less than 8×10-6(1σ) could be achieved for 29 Si/ 28 Si and 30 Si/ 28 Si by taking an integration time of 8 seconds. The long-term reproducibility of 0 . 06‰-0 . 10‰ ( 2σ, n=20 ) was obtained for δ29 Si and δ30 Si by repeating the analysis of the silicon reference materials, whilst the determined isotopic value for GBW04421 and GBW04422 were in good agreement with the recommended data, suggesting the precision and robustness of this method. The measured silicon isotopic values of fresh waters ( river and lake waters ) , saline waters and seawater demonstrated the capability of applying this method to trace the biogeochemical processes of silicon in natural waters.