| Popis: |
The reproducibility as the standard deviation or standard error of analytical data is used to estimate the performance ability of the isotope ratio mass spectrometer (IRMS). The standard deviation of □^13C value of a sample is not supposed to be the same on a wide range of sample weights. In order to determine the suitable sample amounts required for high precision and accuracy and the factors required for optimal equipment conditions, certified reference materials were repeatedly measured with various weight ranges using an elemental analyzerisotope ratio mass spectrometer (EA-IRMS). The measured □^13C values of the standards EMA-P1 and EMAP2 fell within the certified value ±2σ with the minimum carbon contents of 102.107 μg and 116.879 μg, respectively. In addition, for the two standards, the peak height ratios calculated by the CO_2(^12C^16O^16O) peak height of the sample to the working standard were 62.8% and 66.8%, respectively. The isotopic composition change was also investigated by the fractionation factor □applied and did not show a large difference in a wide range of sample weight for the two standards. We suggest that carbon isotope composition needs to be determined by considering several factors such as element contents, standard deviation of □^13C value, peak height ratio(or peak height) and fractionation factor □applied. |
