Element analysis-mass spectrometry (EA-MS) is widely applied to determine samples' nitrogen isotopic composition in environmental and geological fields. In this research work, the suitable experimental conditions ...Element analysis-mass spectrometry (EA-MS) is widely applied to determine samples' nitrogen isotopic composition in environmental and geological fields. In this research work, the suitable experimental conditions for surface and loess sample measurement were chiefly ascertained. Further more, the negative influences in soil measurement,such as sample's uncompleted reaction, baseline excursion and the decline of oxidation capacity were stressed. The results show that the measurement precision of nitrogen isotopes can be hold less than ±0. 3‰, with Cr2O3/Co3O4Ag Oxidation Furnace, 80-90mL/min for Carrier-He flowrate, 80kPa for Conflo-He pressure and 100mL/min for Oxygen injection.展开更多
该文建立液相色谱-稳定同位素比值质谱联用(liquid chromatography-stable isotope ratio mass spectrometry,LC-IRMS)检测抗坏血酸δ^(13)C值的分析方法,用于鉴别针叶樱桃粉中抗坏血酸天然来源的真实性。样品中抗坏血酸经液相色谱在线...该文建立液相色谱-稳定同位素比值质谱联用(liquid chromatography-stable isotope ratio mass spectrometry,LC-IRMS)检测抗坏血酸δ^(13)C值的分析方法,用于鉴别针叶樱桃粉中抗坏血酸天然来源的真实性。样品中抗坏血酸经液相色谱在线分离纯化,优化后色谱条件为:Syncronis C18(250 mm×4.6 mm,5μm)色谱柱,流动相为水-pH 2的硫酸溶液(90∶10,体积比),流速0.250 mL/min,色谱柱温度30℃,进样量10μL,通过LC-IsoLink实现目标物全部氧化为CO_(2)气体,最终以气态形式进入稳定同位素质谱仪,直接检测样品中抗坏血酸的δ^(13)C,该方法结果稳定、准确。分别测定了7个合成来源的维生素C片和19个针叶樱桃粉,结果表明,天然来源抗坏血酸δ^(13)C值为-25.00‰~-22.01‰,合成来源抗坏血酸δ^(13)C值为-11.74‰~-10.28‰,两者分布显著性差异,该方法可用于抗坏血酸产品标识的真实性鉴别研究。展开更多
文摘Element analysis-mass spectrometry (EA-MS) is widely applied to determine samples' nitrogen isotopic composition in environmental and geological fields. In this research work, the suitable experimental conditions for surface and loess sample measurement were chiefly ascertained. Further more, the negative influences in soil measurement,such as sample's uncompleted reaction, baseline excursion and the decline of oxidation capacity were stressed. The results show that the measurement precision of nitrogen isotopes can be hold less than ±0. 3‰, with Cr2O3/Co3O4Ag Oxidation Furnace, 80-90mL/min for Carrier-He flowrate, 80kPa for Conflo-He pressure and 100mL/min for Oxygen injection.
