The Study on Accuracy and Precision of Nitrogen Isotope Measurement Using Elemental Analyzer-Isotope Ratio Mass Spectrometer (EA-IRMS) |
원소분석기와 연계된 동위원소질량분석기(EA-IRMS)를 이용한 질소안정동위원소비 측정의 정확도·정밀도 연구 |
김보경, 이상욱, 김민섭, 이원석, 황종연 |
국립환경과학원 |
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Abstract |
To estimate the performance ability of an elemental analyzer-isotope ratio mass spectrometer (EA-IRMS),the reproducibility of analytical data on a standard material was evaluated. In order to determine the suitable sample amounts required for high precision and accuracy and the factors required for optimal equipment con-ditions, a certified reference material EMA-P2 was repeatedly measured with varying sample weights. The δ15N values were measured about 1‰ higher than the certified value. The copper reagent reducing an excess of oxygen and removing oxygen from NO xin reduction tube of elemental analyzer (EA) was replaced with new copper material. Consequently, the measured δ15N values of the EMA-P2 fell within the certified value ±2σ with the minimum nitrogen contents of 18.650 µg and minimum peak height ratio of 14.820%. The factor εapplied calculated with nitrogen isotope ratio (15N/14N) of the sample to the working standard had a wide range within the certified value ±2σ. However, the factor εapplied showed the narrow range from 0.3130 to 0.7344within the certified value ±1σ. We suggest that nitrogen isotope composition needs to be determined by con-sidering several factors such as nitrogen contents, standard deviation of δ15N value, peak height ratio (or peak height) and factor εapplied. |
Key Words:
EA, IRMS, δ15N value, Nitrogen isotope, Precision, Accuracy, Element contents, Peak height,Factor εapplied |
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