水平衡法与高温转化法在矿泉水氢氧稳定同位素测定中的应用

为了鉴别不同品牌矿泉水标注水源地信息真伪,对11种不同品牌饮用水的氢氧稳定同位素(δD和δ18 O)进行测定。结果表明,水平衡法(GasBench-IRMS)和高温转化法(TC/EA-IRMS)的测定结果一致性较好,两种方法测定6种不同饮用水的δD和δ18 O的平均差异分别为(0.6±1.59)‰和(0.02±0.13)‰。水平衡法需要较长的制备和测定时间,但δD和δ18 O的测定精度明显优于高温转化法。11种饮用水δD和δ18 O变化范围较大,其δD和δ18 O受不同品牌饮用水的水源地降水影响形成明显的地域性。虽然无法区分矿泉水是否由其他类别饮用水伪造,但δD和δ18 O可以为特定区域(如高海拔与沿海地区)以及产地相近的矿泉水水源地鉴别提供依据。

Application of GasBench-IRMS and TC/EA-IRMS on Measurement of δD andδ18O in Mineral Water

Source regions of different mineral water largely determines their market value and price. To identify the authenticity of source regions, hydrogen and oxygen isotopes (δD andδ¹⁸O) of 11 different brand drinking water was measured through two methods of aqua equilibration technique (GasBench-IRMS) and the reduction of H₂O at high temperature (TC/EA-IRMS). Our results indicated that the measurement results of GasBench-IRMS were well consistent with those of TC/EA-IRMS. The difference were (0.6±1.59)‰ for δD, and (0.02±0.13)‰ forδ¹⁸O, respectively. Based on the GasBench-IRMS, more measurement time was required. However, it would give a better precision for δD andδ¹⁸O than that of TC/EA-IRMS. There were obvious changes in δD andδ¹⁸O of 11 different brand drinking water (including 8 kinds of mineral water). The δD andδ¹⁸O of different brand drinking water had notable regional features, which were mainly produced and influenced by local precipitation. Although the product authenticity could not be identify accurately, δD andδ¹⁸O of mineral water provided information about the water source for mineral water of special areas (e.g., high altitude and coastal regions). Through the database establishment of δD andδ¹⁸O in future studies, these results will gave implication for the quick water source identification for mineral water.