Ma Kang, Wang Haifeng, Zhao Min, Xing Jinjing
Division of Chemical Metrology and Analytical Science, National Institute of Metrology, Beijing 100013, China.
Anal Chim Acta. 2009 Sep 21;650(2):227-33. doi: 10.1016/j.aca.2009.07.046. Epub 2009 Jul 23.
Purity determination of pure organic substance is essential for the establishment of traceability to SI units. A mass balance method was employed to determine the purity of theophylline certified reference materials (CRM), compared with high performance liquid chromatography (HPLC) and differential scanning calorimetry (DSC). In the approach of the mass balance, the impurities were identified by ion trap time-of-flight mass spectrometer (IT-TOF-MS) and quantified by HPLC. The purity of theophylline CRM determined by mass balance method was 99.82% with an extended uncertainty of 0.1% (k=2). The uncertainty evaluation of purity demonstrated that the accuracy of the mass balance method is better than that of HPLC and DSC. It indicated that the mass balance is suitable for the CRM and pharmaceutical standards.
纯有机物质的纯度测定对于建立溯源至国际单位制（SI）单位至关重要。采用质量平衡法测定茶碱标准物质（CRM）的纯度，并与高效液相色谱法（HPLC）和差示扫描量热法（DSC）进行比较。在质量平衡法中，杂质通过离子阱飞行时间质谱仪（IT-TOF-MS）进行鉴定，并通过HPLC进行定量。采用质量平衡法测定的茶碱CRM纯度为99.82%，扩展不确定度为0.1%（k=2）。纯度的不确定度评估表明，质量平衡法的准确度优于HPLC和DSC。这表明质量平衡法适用于CRM和药品标准。
