Department of Industrial Engineering, University of Trento, Via Sommarive 9, 38123 Trento, Italy.
Department of Civil, Chemical, Environmental, and Materials Engineering, University of Bologna, Via Terracini 28, 40131 Bologna, Italy.
Int J Environ Res Public Health. 2019 Apr 19;16(8):1419. doi: 10.3390/ijerph16081419.
Nitrate and bromide ions are generally considered indicators of anthropogenic pollution and seawater intrusion, respectively, in the groundwater of coastal territories. The analysis of these species is generally carried out with routine chromatographic analyses which generally afford partially merged or poorly resolved peaks. In the present paper a simple method for the correct evaluation of their concentration in water is reported. This method does not imply utilization of other instruments or technologies, only the mathematical elaboration of the data obtained from routine analysis of standard solutions containing the two species. Standard binary solutions of nitrate and bromide ions at different concentrations, ranging between 0.1 and 2 mM, were analyzed by means of ion chromatography. Splitting two partially merged chromatographic peaks and considering each resulting area as originating from a single species produces "measured" concentration values which differ from the nominal ones. Such a procedure generates errors (one per species) which can be written as a function of the above mentioned "measured" concentrations and which can be graphically represented by means of a surface in a three-dimensional (3D) space. In this way, "measured" concentrations of bromide and nitrate ions can be corrected by calculating the errors generated under the experimental conditions at which the chromatographic separation is performed. Notably, this is analogous with the two-dimensional (2D) calibration normally carried out for analytical purposes. Indeed, both methods allow estimation of the unknown concentration of species in solution by correlating the instrumental response with the concentration of standard solutions.
硝酸盐和溴化物离子通常分别被认为是沿海地区地下水中人为污染和海水入侵的指标。这些物质的分析通常采用常规的色谱分析方法，但这些方法通常只能得到部分合并或分辨率较差的峰。本文报道了一种简单的方法，可以正确评估水中这些物质的浓度。该方法不涉及其他仪器或技术的使用，只需对含有这两种物质的标准溶液的常规分析数据进行数学处理即可。采用离子色谱法对不同浓度（0.1 至 2mM）的硝酸盐和溴化物离子的标准二元溶液进行了分析。将两个部分合并的色谱峰分开，并将每个得到的区域视为源自单一物质，从而产生与标称值不同的“实测”浓度值。这种方法会产生误差（每个物质一个），这些误差可以表示为上述“实测”浓度的函数，并可以通过三维（3D）空间中的曲面图形表示。这样，就可以通过计算在进行色谱分离的实验条件下生成的误差来校正溴化物和硝酸盐离子的“实测”浓度。值得注意的是，这与通常用于分析目的的二维（2D）校准类似。实际上，这两种方法都可以通过将仪器响应与标准溶液的浓度相关联来估计溶液中未知物质的浓度。
