丙体六六六纯度标准物质的研制与定值分析

Development and Characterization for the Purity of Gamma-hexachlorocyclohexane

建立丙体六六六纯度标准物质的定值及不确定度评定方法,成功研制了丙体六六六纯度标准物质。原料成分采用气相色谱-质谱法(GC-MS)、红外光谱法(IR)和核磁共振法(1H和13CNMR)进行准确定性。通过均匀性及稳定性考察并检验合格后,采用两种不同原理和精度的方法,即质量平衡法和差示扫描量热法(DSC)进行有机纯度定值。原料中的水分和灰分杂质分别用卡尔费休法、马弗炉灰化燃烧法进行测定。研制的丙体六六六纯度标准物质纯度为99.5%。对定值结果进行不确定度评估,得到扩展相对不确定度为0.4%(k=2)。通过比对分析和第三方实验室量值核验,进一步确保定值结果的准确、可靠。该纯度标准物质已被国家质量监督检验检疫总局批准为国家二级有证标准物质[编号GBW(E)061724],可作为测量和量值溯源标准,为相关部门提供服务。

A reference material of Gamma-hexachlorocyclohexane （T-HCH） was developed in this work. The methodologies re- garding characterization and uncertainty assessment of T-HCH were established. Firstly, accurate qualitative analysis of T-HCH pure material was performed by gas chromatography coupled with mass spectrometry （GC-MS） ,infrared spectrometry （IR） , and nuclear magnetic resonance spectrometry （NMR）. After then, homogeneity test, as well as short-term and long-term stability test was conducted. Mass balance and differential scanning calorimetry （DSC） ,these two methods with different principle and precision were applied to determine the purity of organic principal component of T-HCH raw material. The content of water and ash were measured by Karl-Fischer method and incineration combustion method. The purity of γ-HCH raw material resulted to be 99.5% ,with the relative expanded uncertainty evaluated to be 0.4% （ k = 2）. The produced certified reference material was further confirmed via comparation analysis,and verify checked by a third party test laboratory for ensuring the accuracy and reliability of the results of characterization. Now,pure 7-HCH was authorized to be a national secondary reference material with authorization number GBW （E） 061724 by general administration of quality supervision, inspection, and quarantine of the PRC. It could be used as measurement standard and value traceability standard in all parties concerned.