원소분석기와 연계된 동위원소질량분석기(EA-IRMS)를 이용한
질소안정동위원소비 측정의 정확도·정밀도 연구
김보경·황종연·이상욱·김민섭·이원석†
국립환경과학원 환경측정분석센터

The Study on Accuracy and Precision of Nitrogen Isotope Measurement
Using Elemental Analyzer-Isotope Ratio Mass Spectrometer (EA-IRMS)
Bo-kyong Kim, Jong-yeon Hwang, Sang-uk Lee, Min-seob Kim, and Won-seok Lee†
Environmental Measurement & Analysis Center, National Institute of Environmental Research,
Environment Research Complex, Incheon 404-708, Korea
Received January 18, 2013/Revised February 5, 2013/Accepted March 11, 2013

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 conditions,
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 NOx in 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 0.7344
within the certified value ±1σ. We suggest that nitrogen isotope composition needs to be determined by considering
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