RESUMO
Due to its high analysis speed and acceptable accuracy, the Spark Atomic Emission Spectroscopy method has been used widely in steel production factories. Since the accuracy of the results dramatically impacts the quality of the final product, the measurement uncertainty must be calculated and presented along with the analysis results. The primary purpose of this paper is to present a method for estimating the measurement uncertainty of carbon determination in carbon and low alloy steel by spark atomic emission spectroscopy. After identifying the factors influencing the test results, we presented a method for quantification and calculation of each source contribution to the combined uncertainty using mathematical and statistical methods. Finally, the amount of expanded uncertainty is determined for a 95% of confidence level. It was found that the measurement uncertainty is mainly affected by the calibration curve, while the analyst error has no significant effect on the measurement uncertainty. The extended relative uncertainty of 0.01 was determined at the 95% confidence level with a coverage factor k = 2.