Exploration of a 3D nano-channel porous membrane material combined with laser-induced breakdown spectrometry for fast and sensitive heavy metal detection of solution samples

Abstract

In this paper, a nano-channel material was combined with laser induced breakdown spectroscopy (LIBS) to achieve sensitive and quick detection of metal ions in liquid samples. A 3D anodic aluminum oxide porous membrane (AAOPM) was selected as a novel substrate for the first time, which showed excellent potential for liquid analysis. It is worth mentioning that the LIBS signal of the target elements in aqueous solution dropped on the 3D AAOPM was increased by up to 19 times in comparison with that on the tablet sample made of aluminium oxide powder. The attractive results are mainly attributed to the peculiar structure of the 3D AAOPM. Firstly, an abundant strong coordination metal–oxygen bond between hydroxyl groups and metal ions existed on the surface of the novel substrate. Secondly, the extremely high aspect ratio of the 3D AAOPM could supply a much larger contact area between the matrix and analytes. Thirdly, the special nano-channel distribution could make efficient coupling of a laser beam with the materials. Finally, the sample pervasion and volatilization could be finished within a very short time because of the micrometer level thickness and porosity of the 3D AAOPM. The calibration curves with linearity ranges (1–100 μg mL⁻¹) and good linearity (R squared better than 0.983 for all of the four target elements) were established, and the limits of detection (LODs) obtained were 0.18 μg mL⁻¹, 0.12 μg mL⁻¹, 0.081 μg mL⁻¹, and 0.11 μg mL⁻¹ for Cu²⁺, Ag⁺, Pb²⁺, and Cr³⁺, respectively. In real sample analyses, the recoveries of three elements at different concentration levels were all in the range of 92.5–107.4%, with the relative standard deviations of parallel samples around 10.0%. This novel method showed a fast, simple and super sensitive monitoring tool for liquid sample analysis compared with the traditional LIBS method.