双路进样稳定同位素质谱仪

同位素溯源技术是国际上目前应用于追溯不同来源食品和实施产地保护的有效工具之一，在食品溯源领域有着广阔的应用前景，在国际上纷纷开展此领域的研究。本文着重阐述了稳定同位素比质谱在食品溯源中的应用。

Analysis of the hydrogen and oxygen stable isotope ratios of beverage waters without prior water extraction using isotope ratio infrared spectroscopyHydrogen (d2H) and oxygen (d18O) stable isotope analysis is useful when tracing the origin of water in beverages, but traditional analytical techniques are limited to pure or extracted waters. We measured the isotopic composition of extracted beverage water using both isotope ratio infrared spectroscopy(IRIS specifically, wavelength-scanned cavity ring-down spectroscopy) and isotope ratio mass spectrometry (IRMS). We also analyzed beer, sodas, juices, and milk ‘as is’ using IRIS. For IRIS analysis, four sequential injections of each sample were measured and data were corrected for sample-to-sample memory using injections (a) 1-4, (b) 2-4, and (c) 3-4. The variation between d2H and d18O values calculated using the three correction methods was larger for unextracted (i.e., complex) beverages than for waters. The memory correction was smallest when using injections 3-4. Beverage water d2H and d18O values generally fit the Global Meteoric Water Line, with the exception of water from fruit juices. The beverage water stable isotope ratios measured using IRIS agreed well with the IRMS data and fit 1:1 lines, with the exception of sodas and juices (d2H values) and beers (d18O values). The d2H and d18O values of waters extracted from beer, soda, juice, and milk were correlated with complex beverage d2H and d18O values (r¼ 0.998 and 0.997, respectively) and generally fit 1:1 lines. We conclude that it is possible to analyze complex beverages, without water extraction, using IRIS although caution is needed when analyzing beverages containing sugars, which can clog the syringe and increase memory, or alcohol, a known spectral interference.

树轮常用于研究气候变化与环境演变，通过对其稳定同位素的分析，可揭示生态系统碳—水—氮变化特征及相互作用。树木在生长发育中响应环境变化，将环境信息通过水/空气/土壤中的碳、氢、氧转化为树木年轮的同位素比值变化，从而为重建环境变化提供了一份可靠的“档案”。古气候变化研究载体有树轮、石笋、海洋/湖泊沉积物和冰芯等。其中树轮样本具有两大优势:1）定年精确，分辨率可以到年；2）树轮年表的每一部分都可以和其它树木(年表)重叠搭接,能够获取平均值。稳定碳同位素：气孔导度、光合速率氧氢同位素：温度、叶片蒸腾作用