根据GB/T 15000.3-2008设计了苯系物标准气体的时间稳定性研究方案,制备了4瓶苯系物标准气体,随着时间的推移进行测定并将结果制图,结果显示量值随时间没有显著的变化趋势.以线性关系为模型,计算线性直线的斜率和斜率的标准偏差,用t检验判断斜率是否显著来评价标准气体的稳定性.计算结果显示,所有斜率均不显著,因此该研究制备的苯系物标准气体能够稳定保存22个月.根据时间稳定性数据计算由不稳定性引起的不确定度,并讨论了这种计算不稳定性引起不确定度的方法对结果有放大的可能性.%The experiment design and data evaluation of long-stability is according to GB/T 15000.3-2008. Standards werernprepared using the gravimetric technique. A batch of 4 cylinders containing BTEX7 at a concentration of 9 μmol/mol level wasrnprepared. Under identical conditions, individual Sample was measured as time elapses over a period of 22 months. The analysisrnof BTEX7 was conducted using a gas chromatograph equipped with a hydrogen flame ionization detector. New primary standardsrnwere prepared before reanalyzing gas standards samples for long-term stability. The analytical data of four standards showed nornmeaningful trend, so the straight line is used as an empirical model. The slopes and the standard deviations in slopes of all fourrnstraight lines were computed, and the slope of the line can be tested for significance using an appropriate t-factor. Comparing therndeviations of the slopes, all slopes are insignificant. As a consequence, no instability was observed. BTEX7 gas standardrnreference material in nitrogen can be stable at least 22 months. The stability data were used as an estimation of the uncertaintyrndue to instability.
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