差示扫描量热法和质量平衡法测定林丹的纯度

Determination of purity of Lindane by differential scanning calorimetry and mass balance

目的通过差示扫描量热法(differential scanning calorimetry,DSC)和质量平衡法(mass balance,MB)2种不同方法对林丹(γ-丙体六六六)纯度标准物质进行纯度分析的研究。方法基于Van’t Hoff原理,即物质的熔融曲线来算出杂质含量,利用DSC法对林丹进行纯度分析;采用气相色谱面积归一化法测量林丹的主成分纯度值,顶空-气相色谱法测量溶剂残留,卡尔费休测定水分和灼烧法测定灼烧残渣来最终确定林丹纯度。结果 DSC法测定林丹纯度为99.92%,不确定度为0.05%,质量平衡法测得林丹纯度为99.74%,不确定度为0.02%。结论 2种不同原理的方法对林丹纯度的测量有较好的一致性。DSC法方法简单,可操作性强,所需样品量较小,对仪器精度要求较高,相对不确定度较大。质量平衡法适用于所有有机纯物质的纯度分析,考察因素较多,分析较全面,且不确定度相对较小,方法准确度高。

Objective To investigate the purity of Lindane（γ-propyl hexavalent hexamethylene） purity reference materials by differential scanning calorimetry（DSC） and mass balance（MB）. Methods Based on the principle of Van＇t Hoff, that is, the melting curve of the material to calculate the impurity content, the purity of the Lindane was analyzed by the DSC method. The main component purity values of Lindane were measured by gas chromatographic area normalization method, and solvent residues were measured. The ash content was determined by Karl Fischer＇s moisture and ignition method to determine the final Lindane purity. Results The purity of Lindane determined by DSC method was 99.92%, and the uncertainty was 0.05%. While the purity of Lindane determined by mass balance method was 99.74%, and the uncertainty was 0.02%. Conclusion The two different methods have good consistency in the measurement of Lindane purity. The DSC method is simple, operability, and required less samples. It requires high accuracy of the instrument and relatively large uncertainty. The mass balance method is applicable to the analysis of the purity of all organic pure substances. There are many factors to be investigated, and the analysis is more comprehensive, with relatively smaller uncertainty and the higher accuracy.