Knopf Burkhard, Rüdel Heinz, Hansknecht Dirk, Klawonn Thorsten, Kreuzer Knut
Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Schmallenberg, Germany.
Röhm GmbH, Deutsche-Telekom-Allee, Darmstadt, Germany.
Environ Sci Pollut Res Int. 2021 Apr;28(13):16244-16252. doi: 10.1007/s11356-020-12062-7. Epub 2020 Dec 17.
Cyanide compounds are naturally emitted into the environment in low levels by degradation processes or emitted from anthropogenic sources. In surface water, complex cyanide compounds as well as "free cyanide" are present. The latter term covers hydrogen cyanide and cyanide compounds which easily liberate hydrogen cyanide under slightly acidic conditions. Especially free cyanide may cause adverse effects in the environment. To exclude negative impacts on freshwater systems, in the context of the European Water Framework Directive (WFD), preventive regulatory activities for free cyanide are currently under discussion. However, established analytical methods for quantification of free cyanide only obtain limits of quantification (LOQs) in the range of 1 μg L. Thus, these methods are not sufficiently sensitive for a potential environmental quality standard (EQS) compliance monitoring at water concentrations below the current predicted no effect concentration (PNEC) level of free cyanide. In the present study, a standardized continuous flow analysis (CFA) method for quantification of low free cyanide concentrations was adapted by applying a special system which allows an ultra-sensitive photometric detection of a colored cyanide derivative. By this means, LOQs in a range of one magnitude below the PNEC are achievable. The method was validated according to ISO/IEC 17025 requirements. Free cyanide concentrations in tested surface water samples from a small river and a barrier lake with low anthropogenic influences were very low and clearly below the PNEC. The results prove that the adapted CFA method is suitable for the analysis of low concentration free cyanide in freshwaters and appropriate for a possible EQS compliance monitoring.
氰化物化合物通过降解过程以低水平自然排放到环境中，或从人为来源排放。在地表水中，存在复杂的氰化物化合物以及“游离氰化物”。后一术语涵盖氰化氢和在微酸性条件下容易释放氰化氢的氰化物化合物。特别是游离氰化物可能会对环境造成不利影响。为了排除对淡水系统的负面影响，在欧洲水框架指令（WFD）的背景下，目前正在讨论针对游离氰化物的预防性监管活动。然而，已有的游离氰化物定量分析方法仅能获得1μg/L范围内的定量限（LOQ）。因此，这些方法对于监测水浓度低于游离氰化物当前预测无效应浓度（PNEC）水平时潜在的环境质量标准（EQS）合规性而言不够灵敏。在本研究中，通过应用一种特殊系统对低游离氰化物浓度的标准化连续流动分析（CFA）方法进行了改进，该系统能够对一种有色氰化物衍生物进行超灵敏光度检测。通过这种方式，可以实现低于PNEC一个数量级范围内的LOQ。该方法根据ISO/IEC 17025要求进行了验证。来自一条小河和一个受人为影响较小的堰塞湖的测试地表水样品中的游离氰化物浓度非常低，明显低于PNEC。结果证明，改进后的CFA方法适用于分析淡水中低浓度的游离氰化物，并且适合可能的EQS合规性监测。
