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质量平衡法分析1,2,3,4-四氯苯的纯度分析与不确定度评定

Analysis of Purity and Uncertainty for 1, 2, 3, 4-Tetrachlorobenzene with the Mass Balance Method

  • 摘要: 采用可溯源的质量平衡法对1,2,3,4-四氯苯标准物质纯度定值,评价了此方法的不确定度。其中非挥发性杂质用气相色谱串联质谱(GC-MS)进行定性,经标准添加的方式确认杂质为1,2,3,5-四氯苯,并用气相色谱电子捕获检测器(GC-ECD)对杂质准确定量;水分含量和灰分含量分别采用卡尔费休库伦法和马弗炉灼烧的方法测量,溶剂残留采用顶空GC-MS分析,确认1,2,3,4-四氯苯中的残留溶剂是乙醚。纯度定值结果为98.79%,扩展不确定度为0.20%(k=2)。同时对分装的500瓶样品抽取10瓶进行均匀性检验,F检验和T检验结果表明在95%置信范围内样品均匀性良好;按短期稳定性(1个月)和长期稳定性(12个月)分别进行稳定性检验,结果表明在20℃条件下1,2,3,4-四氯苯的稳定期不少于12个月。

     

    Abstract: A traceable method is presented, to study the purities of certified reference material of 1,2,3,4-tetrachlorobenzene with the assessment of uncertainties. The purities of 1,2,3,4-tetrachlorobenzene were determined by the mass balance method. The qualitative analysis of main non-volatile impurities was identified as 1,2,3,5-tetrachlorobenzene with Gas Chromatography-Mass Spectrometry (GC-MS) and standard addition. The quantitative analysis for the impurities was measured by Gas Chromatography-Flame Ionization Detector (GC-FID). The content of water and ash in 1,2,3,4-tetrachlorobenzene were respectively measured by Karl-Fischer titrator and ignited at 900℃ in a muffler roaster. The residuals of solvent were confirmed as ethyl ether by Headspace Gas Chromatography-Mass Spectrometry. The certified result with the mass balance method was 98.79% and the expanded uncertainty was 0.20% (k=2). The good homogeneity result in the 95% confidence interval was validated by F-test and t-test statistical methods with samples from 500 different bottles. The stability inspection was carried out on short-term (one month) and long-term (12 months) tests, and the results indicate that the stability period for 1,2,3,4-tetrachlorobenzene of storage is no less than 12 months at 20℃.

     

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