MnCl_2改性γ-Al_2O_3毛细管填充柱气相色谱分析氢同位素

针对常规气相色谱填充柱分析稳定氢同位素的柱效低、峰宽大、保留时间长等问题,采用MnCl_2改性γ-Al_2O_3填充的石英毛细管柱开展了系统性柱效分析及氢同位素分析技术研究。研究结果表明,使用MnCl_2对γ-Al_2O_3进行改性后,可大大改善单纯的γ-Al_2O_3表面有序度、孔结构和吸附性质,并将正氢(o-H_2)和仲氢(p-H_2)峰洗脱在单一谱峰区域内。制备的长1.0 m、内径0.53 mm的石英毛细填充柱与热导检测器(TCD)级联测试,在体积浓度1至10 m L/L范围内有较好的线性关系,对于低浓度样品检测的相对误差不大于5%。H_2、HD和D_2的保留时间可分别缩短至39、46和60 s,检出限可分别降低至0.046、0.067和0.072 m L/L。毛细管填充柱较常规填充柱具有峰形尖锐、相邻组分分离度高、保留时间短、检出限低等优点,可用于低浓度氢同位素快速测量及氢同位素在线分析。

Analysis of hydrogen isotopes by gas chromatography using a MnCl2 coated γ-Al2O3 capillary packed column

The conventional packed column gas chromatographic analysis of hydrogen isotopes has low column efficiency, broad peak and long retention time. In this work, a γ-Al₂O₃ with MnCl₂ coated capillary packed column was tested at cryogenic temperature. The systematic column efficiency analysis and the hydrogen isotopes analytical technique research had been carried out. The results showed that, the γ-Al₂O₃ with MnCl₂ coating could greatly improve the surface degree of order, pore structure and adsorption properties. Also the o-H₂ peak and p-H₂ peak were eluted in a single area. The γ-Al₂O₃ with MnCl₂ coating was packed into a 0.53 mm inner diameter and 1.0 m long fused silica capillary column. It had a good linear relationship used this column with thermal conductivity detector (TCD) to detect the volume concentrations of hydrogen isotopes from 1 to 10 mL/L, and the relative error was less than 5% for low concentration sample testing. For H₂, HD and D₂, the retention times can be shortened to 39, 46 and 60 s, respectively. The limits of detection were reduced to 0.046, 0.067 and 0.072 mL/L, respectively. Compared with conventional packed column, capillary packed column had sharper peak form, higher separation degree of adjacent components, shorter retention time and lower detection limits. The above results indicate that the capillary packed column with TCD detector can be used for fast detection of low concentration of hydrogen isotopes and their online analysis.