Department of Chemistry, Mokpo National University, Jeonnam 534-729, Korea.
Appl Spectrosc. 2012 Dec;66(12):1385-96. doi: 10.1366/12-06639R.
We report a simple sub parts per million (sub-ppm) detection method for heavy metals in water by laser-induced breakdown spectroscopy (LIBS). Filter papers were used as the substrates for both transforming aqueous solutions to solid samples and for pre-concentrating dissolved heavy metal ions. The amount of sample uptake was 1.2 g by soaking a filter paper. This provides limit-of-detection (LOD) values of 2.7 and 0.36 ppm for Pb and Cr, respectively. The LODs could be improved remarkably by pre-concentrating the heavy metal ions. When a 40 g sample solution was evaporated on a filter paper, the LODs of 75 and 18 parts per billion (ppb) were obtained for Pb and Cr, respectively. Moreover, by either increasing the evaporated amount of sample solution or applying an argon gas flow, further improvement of the LODs was found to be very promising. The LIBS spectra of tap water were recorded using the pre-concentration method and are discussed in comparison with the results from inductively coupled plasma atomic emission spectroscopy (ICP-AES). We could observe strong emission lines of Ca, Mg, K, Cu, and Sr in the tap water, of which concentrations were determined to be 6.3, 1.3, 1.1, 0.64, and 0.046 ppm, respectively, by ICP-AES. Our method shows promise as a fast, reliable, water-quality monitoring tool for heavy-metal concentrations as well as for hardness.
我们报告了一种通过激光诱导击穿光谱（LIBS）检测水中重金属的简单亚ppm（sub-ppm）检测方法。滤纸条既用作将水溶液转化为固体样品的基质，也用作预浓缩溶解重金属离子的基质。通过浸泡滤纸条，样品的摄取量为 1.2 克。这为 Pb 和 Cr 分别提供了 2.7 和 0.36 ppm 的检测限（LOD）值。通过预浓缩重金属离子，可以显著提高 LOD 值。当将 40 克样品溶液蒸发在滤纸上时，Pb 和 Cr 的 LOD 值分别为 75 和 18 皮克/分（ppb）。此外，通过增加蒸发的样品溶液量或施加氩气流，可以发现进一步提高 LOD 值非常有希望。使用预浓缩方法记录了自来水的 LIBS 光谱，并与电感耦合等离子体原子发射光谱（ICP-AES）的结果进行了比较。我们可以在自来水中观察到 Ca、Mg、K、Cu 和 Sr 的强发射线，其浓度通过 ICP-AES 分别确定为 6.3、1.3、1.1、0.64 和 0.046 ppm。我们的方法有望成为一种快速、可靠的水质监测工具，用于检测重金属浓度和硬度。
