Zuckerberg Institute for Water Research, Department of Environmental Hydrology and Microbiology, Ben-Gurion University of the Negev, Sede Boqer Campus, 8499000, Israel.
Zuckerberg Institute for Water Research, Department of Environmental Hydrology and Microbiology, Ben-Gurion University of the Negev, Sede Boqer Campus, 8499000, Israel.
J Hazard Mater. 2020 Apr 15;388:122036. doi: 10.1016/j.jhazmat.2020.122036. Epub 2020 Jan 7.
Bromoxynil is an increasingly applied nitrile herbicide used for post-emergent control of annual broadleaved weeds. Compound-specific isotope analysis (CSIA) of the compound is of interest for studying its environmental fate, yet is challenging following its polar nature. We present a CSIA method for bromoxynil that includes offline thin-layer chromatography purification followed by an elemental analyzer isotope ratio mass spectrometer (EA-IRMS). This method was shown to be accurate and precise for δC and δN analysis of the compound (standard deviation of replicate standards <0.5‰). The method was applied to photodegraded samples, either radiated under laboratory condition with a UV lamp, or exposed to sunlight under environmental conditions. Dominating degradation products were similar in both cases. Nevertheless, isotope effects differed, presenting a strong inverse carbon isotope effect (εC = 4.74 ± 0.82‰) and a weak inverse nitrogen isotope effect (εN = 0.76 ± 0.12‰) for the laboratory experiment, and an insignificant carbon isotope effect (εC = 0.34 ± 0.44‰) and a normal nitrogen isotope effect (εN = -3.70 ± 0.30‰) for the natural conditions experiment. The differences in δC vs. δN enrichment trends suggest different mechanism for the two processes. Finally, the obtained dual isotope trend for natural conditions provide the basis for studying the dominance of photodegradation as a degradation route in the environment.
溴苯腈是一种越来越多应用的腈类除草剂，用于苗后防治一年生阔叶杂草。该化合物的特征同位素分析（CSIA）对于研究其环境命运很有意义，但由于其极性性质，分析具有挑战性。我们提出了一种用于溴苯腈的 CSIA 方法，包括离线薄层层析纯化，然后进行元素分析仪同位素比质谱仪（EA-IRMS）分析。该方法在 δC 和 δN 分析方面具有准确性和精密度（重复标准的标准偏差 <0.5‰）。该方法应用于光降解样品，要么在实验室条件下用紫外线灯辐射，要么在环境条件下暴露于阳光。两种情况下的主要降解产物相似。然而，同位素效应不同，表现出强烈的负碳同位素效应（εC=4.74±0.82‰）和较弱的负氮同位素效应（εN=0.76±0.12‰），而实验室实验中的负碳同位素效应不明显（εC=0.34±0.44‰）和正常的氮同位素效应（εN=-3.70±0.30‰）。δC 与 δN 富集趋势的差异表明两种过程的机制不同。最后，自然条件下获得的双重同位素趋势为研究光降解作为环境中一种降解途径的优势提供了基础。
