Study On Low-concentration Hydrogen Isotope Chromatographic Analysis Techniques In Helium Atmosphere

Gas chromatography was promising for gas component analysis in deuterium tritium fuel cycle,for its readily availability,highly stability,and low cost.However,the long test time,low separation factor,and low detection limit of gas chromatography were not suitable for practical usage.As detector and column were the central parts of gas chromatography in analyzing hydrogen isotopes under low temperature,we focused our research on developing highly sensitive detector and highly functional microporous materials for packed columns.Our gas chromatography with optimized detector and column parameters was suitable for fast and real-time monitoring of hydrogen isotopes,and was promising in miniaturization of gas chromatography.(1)Zirconia galvanic cell was used as detector of gas chromatography in analyzing hydrogen isotopes.Because zirconia galvanic cell was a solid electrolyte cell,it could avoid the thermal conductibility similarity of hydrogen and helium in normal TCD detector.The optimized working temperature was of 700 degree.When flow rate of purge gas is 60 mL/min,the relative standard deviation of the instrument measurement is smaller than 1%,and the relative error is smaller than 5%.The detection limits of H2 and D2 are 15 ppm and 40 ppmrespectively,which were 10 times and 6 times higherthan the TCD detector detection limitrespectively.Zirconia detector can be used to detect trace hydrogen isotopes in helium gas.As H2,D2 and HD result the same electrochemical response,we could use H2 sample to get standard curve to estimate the concentration of D2 and HD samples whenlack of hydrogen isotopes standard sample.(2)When ?-Al2O3 was modified with MnCl2,surface morphology,pore structure and adsorption properties were significantly improved.o-H2 peak and p-H2 were combined in a single peak.The packed column using modified ?-Al2O3 for hydrogen isotope separation has high separation factor and wide linear range.We found that,packedcapillary column has higher column efficiency,sharper peak,higher separation factor,shorter retention time and lower detection limit than conventional packed column.It can be used in real-time detecting low concentration hydrogen isotope.Good linear relationship was maintained using column with 0.53 mmin inner diameter and 1.0 min length to detect the hydrogen isotopes from hundreds of ppm to percentage.For low concentration sample,the relative error is less than 5%.For H2,HD and D2,retention time can be shortened to 39 s 46 s and 60 s,respectively.Detection limit was reduced to 46 ppm 67 ppm and 72 ppm.(3)CPL-1 was a metal organic framework with large surface area and vniform pore diameter.Thiscolumn packed with CPL-1 has awide linear range,good repeatability,and fast analysis speed.The detection limitwas of 250 ppm,and the relative error is less than 4.0%.The relative standard deviation is less than 1%.This material was promising in hydrogen isotope analysis.However,it is difficulty to prepare packed column,further research is needed to in practical applications.