摘要:
基于具有程序升温气相色谱 (GC) 的元素分析-稳定同位素比率质谱仪 (EA-IRMS) 联机系统, 初步建立了总氮、总碳和总硫稳定同位素比率的快速分析方法.分析结果表明:EA-IRMS联机系统运行状态良好, δ (15 ) N、δ (13 ) C和δ34S标准曲线在时间上无显著漂移, 质量控制标准的长时间测量精度优于0.3‰, 准确度优于0.1‰.在18mm的反应管内不存在34S记忆效应, 25mm的反应管在加入空锡囊燃烧后可基本消除34S记忆效应.利用该联机系统分析了不同类型的食品和环境样品.对于C/N、C/S质量比都小于200的样品, δ (15 ) N、δ (13 ) C和δ34S的测定精度均优于0.15‰, 能够满足实验室测试要求.对于C/N或C/S质量比极高的木材和琥珀样品, 在N2和SO2信号强度都小于0.5V的情况下, δ (15 ) N和δ34S也获得了较好的重现性, 其测定精度分别优于0.6‰和0.2‰.该研究可为EA-IRMS技术的应用与发展提供基础数据和科学依据.
Abstract:
Measurements of the bulkδ (15 ) N, δ13C andδ34S were conducted by an element analysis-isotope ratio mass spectrometry (EA-IRMS) , which was equipped with a temperature-ramped gas chromatography (GC) .A fast analysis method was established for the EA-IRMS equipped with temperature-ramped GC.The results indicated that EA-IRMS had a satisfactory running state.The correction curves were set up forδ (15 ) N, δ (13 ) C andδ34S, which had no significant time drifts during the study period (May 2017to October 2017) .The long time precision and accuracy for the EA-IRMS were better than0.3‰and 0.1‰, respectively.There was no 34S memory effect for the 18mm reactor tube.After adding the tin capsules into the EA-IRMS, the 34S memory effect could be eliminated for the 25 mm reactor tube.Different kinds of food and environmental samples (i.e., subabdominal mutton, triceps brachii mutton, longissimus dorsi mutton, biceps femoris mutton, wild sea cucumber, artificial breeding sea cucumber, honeysuckle, kerogen, wood, and amber) were analyzed through EA-IRMS equipped with temperature-ramped GC.The measurement precisions ofδ (15 ) N, δ (13 ) C andδ34S were better than0.15‰for the most part of samples, which could meet the practical demands in laboratory.As for the wood and amber samples, the samples commonly had high C/N or C/S ratio that would influence the analytical precision.Though the ion current intensities of N2and SO (2 ) were less than 0.5 V, the precisions forδ (15 ) N andδ (34 ) S were better than0.6‰and 0.2‰, respectively.The reproducibility of these measurement results had good consistency.Equipped with the temperature-ramped GC, the testing results of this study indicated that the improved EA-IRMS could meet the laboratory's demands.
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