A novel NMR method for the determination and monitoring of evolution of hydrogen peroxide in aqueous solutions
A novel NMR method for the determination and monitoring of evolution of hydrogen peroxide in aqueous solutions
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DOI：
10.1007/s00216-014-7745-4
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发表时间：
2014-05-01
影响因子：
4.3
通讯作者：
Gerothanassis, Ioannis P.
中科院分区：
文献类型：
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作者：
Tsiafoulis, Constantinos G.;Gerothanassis, Ioannis P.
开发了一种新型核磁共振方法，可以快速、直接定量分析质子溶剂中的过氧化氢。该方法基于 H2O2 质子的高度去屏蔽 H-1 NMR 信号（298 K 时类似于千分之一欧元的 11.15 ppm），并结合使用 H2O-DMSO-d(6) 的冷冻保护（防冻）混合物、低温（类似于 260 K）和 pH 效应，以实现最小的质子交换率，从而获得尖锐的 H-1线宽。在室温下，在水中观察到线宽超过 550 Hz 的极宽共振，在很宽的 pH 值范围内，使用上述方法将其降低到 2 Hz 以下，即使使用 10 分钟的非常短的总实验时间，检测限也达到 20.0 μ mol L-1（管内）。该方法适用于希腊牛至的水提取物和水性速溶咖啡。牛至样品的线宽低于 10 Hz，速溶咖啡样品的线宽低于 17 Hz，这导致 (i) 通过加标实验明确分配 H2O2，从而排除与提取物中固有酚类干扰的任何混淆；(ii) 通过易于实验获取的参数实时定量研究 H2O2 的演变。
A novel NMR method that allowed the rapid and direct quantitative analysis of hydrogen peroxide in protic solvents was developed. The method was based on the highly deshielded H-1 NMR signal of the H2O2 protons (delta similar to aEuro parts per thousand 11.15 ppm at 298 K) in H2O and the combined use of cryoprotective (antifreeze) mixtures of H2O-DMSO-d(6), low temperatures (similar to 260 K), and pH effects in order to achieve minimum proton exchange rate and, thus, sharp H-1 line widths. Extremely broad resonances with line widths above 550 Hz at room temperature in H2O were observed in a wide range of pH values, which were reduced below 2 Hz with the use of the above method which resulted in a detection limit of 20.0 mu mol L-1 (in tube) even when using very short total experimental time of 10 min. The method was applied in aqueous extract of Greek oregano and in aqueous instant coffee. Line widths below 10 Hz for oregano samples and 17 Hz for instant coffee samples were obtained which resulted (i) in the unequivocal assignment of H2O2 with spiking experiments precluding any confusion with interferences from intrinsic phenolics in the extracts and (ii) in the quantitative investigation of the evolution of H2O2 in real time with parameters easily accessible experimentally.