Abstract: The δ13C and δ15N of specific compounds can be determined successfully by gas chromatography-combustion-isotope ratio mass spectrometer (GCCIRMS). Precision and accuracy of the measurement processes are two key indicators for evaluating the performance of GCCIRMS, which are also of great significance for defining the detection ability of GCCIRMS. However, the uncertainty of the detection capability of GCCIRMS limits the application of isotopic tracing technology for specific compounds. Therefore, there is an urgent need to comprehensively evaluate the effects of sample size and signal intensity on the δ13C and δ15N measurements by GCCIRMS. In this study, δ13C and δ15N of caffeine compounds and specific amino acids were analyzed under the premise of ensuring high determination precision and accuracy based on GCCIRMS. The results showed that GCCIRMS had good accuracy in determination of δ13C and δ15N under the condition of extremely small sample size and extremely low signal intensity. Specifically, the carbon and nitrogen isotope compositions of caffeine could be determined successful when m/z 44 and m/z 28 signals were higher than 100 mV. The recommended sample size of GCCIRMS should be more than 1 ng C and 5 ng N for caffeine δ13C and δ15N measurements, respectively. The measurement precision and accuracy were better than 03‰ and 02‰ for both caffeine δ13C and δ15N, which could meet the practical demands in the laboratory. Meanwhile, GCCIRMS could ensure sufficient m/z 44 and m/z 28 signals for amino acids, and avoid peaktopeak interference during the determination of amino acids δ13C and δ15N in the mixed systems. For the δ13C and δ15N measurements of amino acids in a complex compound, the chromatographic peaks acquired by GCCIRMS were well separated and presented under minimal injection amounts. The δ13C measured values of 12 specific amino acids ranged from -2956% to -689‰ with a mean measurement accuracy of 056‰. For the δ15N of specific amino acids, the measurement results of GC-C-IRMS were further compared with those of elemental analyzer-isotope ratio mass spectrometry (EA-IRMS) to explore the performance of GCCIRMS in determination of compounds δ15N in the complex system. The measurement results of GCCIRMS had good compatibility with EAIRMS of an average deviation around (077±034)‰. In addition, there was no significant time drift (4 days) for the amino acid δ15N measurement in both systems. Taking into account the advantages of GCCIRMS, such as high sensitivity, wide detection range, and extremely low sample consumption, it will play an important role in the application of compoundspecific isotope technology in the fields of geochemistry and life sciences.