Vereycken Willem, Riaño Sofía, Van Gerven Tom, Binnemans Koen
Department of Chemistry, KU Leuven, Celestijnenlaan 200F, P. O. box 2404, B-3001 Leuven, Belgium.
Department of Chemical Engineering, KU Leuven, Celestijnenlaan 200F, P. O. box 2424, B-3001 Leuven, Belgium.
ACS Omega. 2021 May 17;6(21):13620-13625. doi: 10.1021/acsomega.1c00586. eCollection 2021 Jun 1.
The synthesis of ionic liquids (ILs) usually involves two steps: (i) quaternization of a precursor followed by (ii) a salt metathesis reaction to introduce the desired anion. A consequence of the second step is that most ILs still contain some amount of the initial anion, often chloride. In this work, wavelength dispersive X-ray fluorescence (WDXRF) spectrometry is presented for the direct measurement of chlorides in ILs. The WDXRF settings were optimized, and the system was calibrated for the detection of chloride in several analogues of the commercially available IL Aliquat 336, [A336][X] (with X = I, Br, NO , or SCN). The Cl Kα intensity showed excellent linearity for samples with a conversion >0.80 (approximately Cl < 8000 ppm). Synthetic quality control samples showed that the instrumental error and deviations induced by the calibration procedure were small with maximum values of 1 and 5%, respectively. Detection and quantification limits depended strongly on the matrix (i.e., anion system and dilution) but were relatively low: 42-191 and 127-578 ppm Cl, respectively. Compared with other analytical techniques used for this purpose, the strengths of WDXRF include its ease of use, rapid measurements, the near absence of sample preparation steps, and versatility in terms of anion systems and chloride concentration range.
离子液体（ILs）的合成通常涉及两个步骤：（i）前体的季铵化，接着是（ii）盐复分解反应以引入所需的阴离子。第二步的一个结果是，大多数离子液体仍含有一定量的初始阴离子，通常是氯离子。在这项工作中，提出了波长色散X射线荧光（WDXRF）光谱法用于直接测量离子液体中的氯化物。对WDXRF设置进行了优化，并对该系统进行了校准，以检测市售离子液体Aliquat 336的几种类似物[A336][X]（其中X = I、Br、NO 或SCN）中的氯化物。对于转化率>0.80（约Cl < 8000 ppm）的样品，Cl Kα强度显示出极好的线性。合成质量控制样品表明，校准程序引起的仪器误差和偏差很小，最大值分别为1%和5%。检测限和定量限在很大程度上取决于基质（即阴离子体系和稀释度），但相对较低，分别为42 - 191 ppm Cl和127 - 578 ppm Cl。与用于此目的的其他分析技术相比，WDXRF的优点包括其易于使用、测量快速、几乎无需样品制备步骤以及在阴离子体系和氯化物浓度范围方面的通用性。
