有机化学物质碳氮稳定同位素系列标准物质研制

Preparation of Reference Materials for Carbon and Nitrogen Isotopes of Organic Materials

实验室和研究人员所使用的碳、氮同位素标准物质一般由国际原子能机构(IAEA)获得,然而近年来,随着碳氮同位素在实验室质量监控、方法评价、仪器校准等方面的广泛应用,市场需求量不断增加,IAEA研制的碳、氮同位素标准物质的种类与数量逐渐不能满足科学研究快速发展的需求。我国急需研制适应当今分析技术水平的有机质碳氮同位素国家标准物质用以进行质量监控、方法评价、仪器校准。为保证量值传递精度,本文研制了4个有机化学物质的碳氮稳定同位素标准物质,其中3个为尿素样品,1个为L-谷氨酸。经检验4种标准物质的均匀性通过F值检验,标准物质的δ13 C和δ15 N值经过一年的稳定性检验,特征量值变化在测量方法允许的不确定度范围内,由此判定δ13 C和δ15 N值稳定性良好。由包括研制单位实验室在内的12家实验室协同定值,采用高温燃烧-气体同位素质谱法测定了δ13 C和δ15 N值,系列标准物质δ13 C和δ15 N认定值区间呈梯度分布,δ13 C值为-40‰~0‰,δ15 N值为-10‰~30‰,涵盖了我国天然样品中有机质碳氮稳定同位素组成范围;研制的系列标准物质δ13 C的定值扩展不确定度不大于0.08‰,δ15 N的定值扩展不确定度不大于0.09‰,定值水平与国际标准物质相当。该系列标准物质已被国家质检总局批准为国家一级标准物质,批准号为GBW04494~GBW04497。可被用于地质、生态、环境等多种样品δ13 C和δ15 N比值测定时的分析监控、仪器校准、方法评价、质量保证和质量监控。

BACKGROUND:The carbon and nitrogen isotope reference materials used by laboratories and researchers are generally obtained by the International Atomic Energy Agency(IAEA).However,in recent years,with the widespread use of carbon and nitrogen isotopes in laboratory quality control,method evaluation,and instrument calibration,the market demand continues to increase,and the types and quantities of carbon and nitrogen isotope reference materials developed by IAEA are gradually unable to meet the rapid development of scientific research.The development of national standard materials for carbon and nitrogen isotopes of organic matter that are suitable for the current analytical technology level for quality control,method evaluation,and instrument calibration are urgently needed in China.OBJECTIVES:To prepare carbon and nitrogen isotope reference materials for organic matter.METHODS:In order to ensure the accuracy of the transmission of the value,4 stable carbon and nitrogen isotope reference materials of organic chemical materials were developed,of which 3 were urea samples and 1 was L-glutamic acid.RESULTS:According to the homogeneity test results,no statistically significant heterogeneity was found based on F test.The verified results by variance analysis for four samples showed very good homogeneity for the series.Nearly one-year stability analysis ofδ13 C andδ15 N values confirmed that no statistically significant instability was found.The certified values of the reference materials were determined by an interlaboratory comparison of 12 participating laboratories.Carbon and nitrogen stable isotope ratios were measured using an elemental analyzer coupled with an isotope ratio mass spectrometer.Theδ13 C andδ15 N values of the series of reference materials had a gradient distribution.Theδ13 C values ranged from-40‰to 0‰,and theδ15 N value from-10‰to 30‰,covering the range of organic carbon and nitrogen stable isotope composition in natural samples in China.The extended uncertainty of the series of standard materials was not greater than 0.08‰forδ13 C and not greater than 0.09‰forδ15 N,and the fixed value level was equivalent to that of the international standard materials.This series of reference materials had been approved by the General Administration of Quality Supervision,Inspection and Quarantine of the People’s Republic of China as the national first-level reference materials(GBW04494-GBW04497).CONCLUSIONS:The series of reference materials can be used for analysis and monitoring,instrument calibration,method evaluation,quality assurance and quality monitoring in the determination ofδ13 C andδ15 N ratios of various samples in geology,ecology and environment.