注射称量法配气中的称量线性研究及不确定度评定

Weighing Linearity and Uncertainty Evaluation for Gravimetric Preparation of Reference Gas Mixture Using Injection Method

采用称量法制备混合气体,当加入的原料组分为微量液体时,需要使用气密性良好的注射器进行液体组分的转移。通过准确称量注射器转移前后的质量差来计算加入液体组分的质量,因此需要使用高灵敏度、低载荷的天平。选择称量重复性好的质量比较器,使用标准砝码研究了质量比较器的称量线性关系,建立了注射法加入液体质量的数学模型,评定了该方法的不确定度。使用该方法制备了两瓶氮中苯的混合气体,通过气相色谱进行了一致性分析,对称量过程中引入的不确定度进行了验证。

As the gas mixtures are prepared gravimetrically and the mass of liquid is normally small,using a gas-tight syringe to inject liquid components into gas mixtures is considered to be a delicate introduction method. The mass difference between the syringe with and without liquid is the introduced liquid mass,so a highly sensitive and low capacity balance is required. In this work,a mass-comparator with brilliant repeatability was chosen to do the weighing process,the weighing linearity was checked using standard mass pieces,and a mathematical description of the injection method was established and its uncertainty was evaluated.Then two binary gas mixture of benzene in nitrogen were prepared and verification was done by GC analyzing.