Measurement uncertainty is the prime requirement of any calibration standard which is indented to use for the calibration of any instrument. In this study, uncertainty evaluation for the gravimetric prepared binary component calibration gas mixtures (CGMs) of propane in nitrogen has been performed in a practical way. CGMs are the key for accurate and consistent results in gas analysis. Three CGMs of propane in nitrogen in the range of 5000–11,000 µmol/mol were prepared using gravimetric method according to ISO 6142. Uncertainty estimation of these prepared gas mixture standards is done following the bottom up approach of ISO Guide to the Expression of Uncertainty in Measurement” (ISO/GUM) in which individual contribution of every step of preparation process contributes to the overall uncertainty estimation. According to ISO/GUM guidelines, four main stages are involved for the estimation of uncertainty in any method such as specification of measurand, identification of sources of uncertainty, quantification of these sources of uncertainty and then combining all uncertainty estimates. In this paper, magnitude of all probable uncertainty components is evaluated for the preparation of CGMs. The uncertainty component of the gravimetrically prepared CGMs of propane is found to be 0.34% relative (k = 2) at 95% confidence interval. The purity of components gas and weighing process are found to be the major sources in uncertainty contribution of preparation of calibration gas mixture. The composition of gravimetrically prepared calibration gas mixtures is verified by gas chromatography technique following ISO 6143 standard. The final estimated uncertainty associated with the certified value of CGM is found to be 0.68% relative, which includes both gravimetric and analytical uncertainty components out of which the gravimetric component of measurement uncertainly is estimated in detail in this paper.

测量不确定度是任何用于校准任何仪器的校准标准的主要要求。在这项研究中，以实际方式对丙烷在氮气中的重量法制备的二元组分校准气体混合物 (CGM) 进行了不确定性评估。CGM 是气体分析中获得准确和一致结果的关键。根据 ISO 6142，使用重量法制备了 5000–11,000 µmol/mol 范围内的三种丙烷在氮气中的 CGM。这些制备的气体混合物标准品的不确定度估计是按照 ISO 不确定度表达指南的自下而上的方法进行的。测量”（ISO/GUM），其中制备过程的每个步骤的个人贡献都有助于整体不确定性估计。根据 ISO/GUM 指南，任何方法中的不确定性估计都涉及四个主要阶段，例如指定被测量、确定不确定性来源、量化这些不确定性来源，然后合并所有不确定性估计。在本文中，评估所有可能的不确定性分量的大小以准备 CGM。发现重量法制备的丙烷 CGM 的不确定性成分为 0.34% 相对（k  = 2) 在 95% 的置信区间。发现组分气体的纯度和称量过程是校准气体混合物制备不确定度贡献的主要来源。重量法制备的校准气体混合物的组成通过气相色谱技术按照 ISO 6143 标准进行验证。与 CGM 认证值相关的最终估计不确定度为 0.68% 相对，其中包括重量和分析不确定度分量，本文详细估计了测量不确定度的重量分量。