Matsumoto Nobuhiro, Shimosaka Takuya
National Metrology Institute of Japan (NMIJ), National Institute of Advanced Industrial Science and Technology (AIST).
Anal Sci. 2017;33(9):1059-1065. doi: 10.2116/analsci.33.1059.
The purities of two high-purity organic compounds with a nitroxyl radical moiety were quantified based on their free-radical content using the effective magnetic-moment method. Magnetic moments were measured and X-band electron paramagnetic resonance (EPR) spectra were obtained using a superconducting quantum interference device and X-band EPR spectrometer, respectively, over a wide temperature range of near-room temperature to near-liquid-helium temperature. Concerning measurements of effective g-values using an EPR spectrometer, both the sweep direction and sweep speed were taken into account to obtain accurate g-values. The purities of 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO) and 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl benzoate (4-hydroxy-TEMPO benzoate) were close to 1 kg kg with relative uncertainties of 1%, which represented improved values compared to those obtained by us previously. These results show a possibility for both compounds to act as reference materials in providing reliable quantification of free radicals per unit mass using this analytical method.
基于其自由基含量，采用有效磁矩法对两种含硝酰基部分的高纯度有机化合物的纯度进行了定量。分别使用超导量子干涉装置和X波段电子顺磁共振（EPR）光谱仪，在接近室温到接近液氦温度的宽温度范围内测量磁矩并获得X波段EPR光谱。关于使用EPR光谱仪测量有效g值，考虑了扫描方向和扫描速度以获得准确的g值。2,2,6,6-四甲基哌啶1-氧基（TEMPO）和4-羟基-2,2,6,6-四甲基哌啶1-氧基苯甲酸酯（4-羟基-TEMPO苯甲酸酯）的纯度接近1 kg/kg，相对不确定度为1%，与我们之前获得的值相比有所提高。这些结果表明，这两种化合物有可能作为参考物质，使用这种分析方法对单位质量的自由基进行可靠的定量。
