Simple, Fast Matrix Conversion and Membrane Separation Method for Ultrasensitive Metal Detection in Aqueous Samples by Laser-Induced Breakdown Spectroscopy

Abstract

A fast, low cost, and sensitive sample pretreatment method was specially developed for laser-induced breakdown spectroscopy (LIBS) based on metal precipitation and membrane separation for simultaneous elemental analysis in liquid samples. The metal elements were reacted with the chelating reagent 2,4,6-trimercapto-1,3,5-triazine (TMT) in the first step and separated by mixed cellulose ester microfiltration membrane subsequently. A specific membrane supporter with smaller aperture than the commercially available needle filter was designed and assembled in the presented research to increase the sensitivity. As a result, the detection limits of Cu, Ag, Mn, and Cr obtained in this research were 2.59 ng·mL(-1), 0.957 ng·mL(-1), 0.958 ng·mL(-1), and 1.29 ng·mL(-1) respectively, which were greatly improved from direct liquid analysis by LIBS. Satisfactory linearity, reproducibility, and accuracy were also obtained in the concentration range of 10-120 ng·mL(-1) for all four elements tested at the optimized experimental conditions. The analytical figures of merits of the proposed method are at an advanced level and are comparable to those reported among other non-LIBS research. In addition, the separation mechanism in this research was initially explored and further varied to be based on metal precipitates adsorption by membrane fibers, rather than a regular size-dependent obstruction.

Electrospray deposition followed by laser-induced breakdown spectroscopy (ESD-LIBS): a new method for trace elemental analysis of aqueous samples

“…[10][11][12][13] With the aim to overcome the limitation of LIBS analysis of liquids, different strategies involving the use of sample preparation procedures have been investigated by many authors. Among them, it can be cited the absorption or drying of the sample on a solid matrix, [14][15][16][17][18] the application of solid phase extraction (SPE) procedures, 19,20 or the use of modern microextraction procedures in both Liquid-Liquid Microextraction (LLME) [21][22][23][24] and Solid Phase Microextraction (SPME) 25,26 modalities, among others. In general, the use of these sample preparation procedures prior LIBS detection leads to a substantial improvement in the analytical performance of the method, by decreasing the limits of detection at the low µg L -1 level.…”

A molecular laser-induced breakdown spectroscopy technique for the detection of nitrogen in water

“…8 LIBS has been applied to elemental analyses in many elds. [9][10][11][12] It has many advantages, such as reliable in situ detection, 13 simultaneous multiple element analysis, 14 remote detection, 15 and little or no sample preparation 16 and is used in various elds as an alternative analysis technique for industrial detection, 17,18 mineral exploration, 19 agricultural pollution, 20 food security, 21 and water protection. 22 LIBS has great potential for use in water pollution detection, especially in wastewater detection, such as industrial wastewater containing toxic heavy metals, 23 nuclear industrial wastewater, domestic sewage, 24 and so on.…”

Dispersive micro solid-phase extraction (DµSPE) with graphene oxide as adsorbent for sensitive elemental analysis of aqueous samples by laser induced breakdown spectroscopy (LIBS)

“…An alternative route to improve limits of detection in LIBS is the application of sample preparation procedures. Concretely, the use of Solid Phase Extraction (SPE) processes can improve the quantitative capability of LIBS for liquid samples analysis, leading to LODs at the low µg L -1 levels [12,13]. In recent years, a new modality of SPE, denoted as Solid Phase Microextraction (SPME), is being increasingly used.…”