元素分析計―同位体比質量分析計（EA-IRMS）によるうなぎ加工品試料の炭素・窒素・酸素安定同位体比分析の試験所間比較

抄録

In previous studies, stable carbon, nitrogen and oxygen isotope analyses were probably a useful tool for tracing the geographical origin of processed eels. However, the lack of a reliable technique for isotope ratio measurements is significantly regrettable, and should be improved immediately. Here, we present results of an inter-laboratory test on the EA-IRMS determination of stable carbon, nitrogen and oxygen isotopic compositions (δ¹³C, δ¹⁵N and δ¹⁸O) in processed eel samples. The processed eel samples were distributed and analyzed by a total of 5 laboratories. The variations of the standard deviations for δ¹³C (− 18.7‰ ± 0.2‰) and δ¹⁵N (+ 13.4‰ ± 0.3‰) among laboratories were not very large compared to the instrument uncertainties. The δ¹⁸O values (+ 16.5‰ ± 3.1‰) in processed eel samples showed a large variation among laboratories. This may have been caused by much the contamination of N₂ to the CO peak on the EA-IRMS chromatogram, and may be improved by using a longer GC column or Purge & trap columns for chromatographic separation.