Application of Temperature-Ramped GC on δ¹⁵N, δ¹³C and δ³⁴S Measurements Using EA-IRMS System

Measurements of the bulk δ¹⁵N, δ¹³C and δ³⁴S 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 for δ¹⁵N, δ¹³C and δ³⁴S, which had no significant time drifts during the study period (May 2017 to October 2017). The long time precision and accuracy for the EA-IRMS were better than 0.3‰ and 0.1‰, respectively. There was no ³⁴S memory effect for the 18 mm 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 of δ¹⁵N, δ¹³C and δ³⁴S were better than 0.15‰ 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 N₂ and SO₂ were less than 0.5 V, the precisions for δ¹⁵N and δ³⁴S were better than 0.6‰ 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.