Detection of Arsenic(III) through Pulsed Laser-Induced Desorption/Ionization of Gold Nanoparticles on Cellulose Membranes

作者：Weng Cheng I; Cang Jin Shun; Chang Jia Yaw; Hsiung Tung Ming; Unnikrishnan Binesh; Hung Yu Lun; Tseng Yu Ting; Li Yu Jia; Shen Yu Wei; Huang Chih Ching^*

来源：Analytical Chemistry, 2014, 86(6): 3167-3173.

DOI：10.1021/ac500053e

We have developed an assay based on gold nanoparticle-modified mixed cellulose ester membrane (Au NPs-MCEM) coupled with laser-induced desorption/ionization mass spectrometry (LDI-MS)-for the detection of arsenic(111) ions (arsenite, AsO2-) in aqueous solution. When the Au NPs reacted with lead ions (Pb2+) in alkaline solution (5 mM glycine NaOH, pH 12), Au-Pb complexes, Pb0, and Pb(OH) were formed immediately on the Au NP surfaces. The Pb species reacted rapidly with subsequently added AsO2- to form PbOAs2O3, (PbO)(2)As2O3, and/or (PbO)(3)As2O3 shells (2-5 nm) on the Au NPs%26apos; surfaces. As a result, significant observable aggregation of the Au NPs occurred in the solution. This Pb2+/Au NP probe allowed the detection of AsO2- at concentrations as low as 0.6 mu M with high selectivity (at least 100-fold over other anions and metal ions). To further improve the sensitivity, we prepared Au NPs-MCEM for the LDI-MS-based detection of AsO2- ions. The intensity of the signal for the [Pb](+) ions in the mass spectra increased when the Au NPs-MCEM reacted with AsO2-; in contrast, the intensity of the signal for [Au](+) ions decreased. Accordingly, the [Pb](+)/[Au](+) peak ratio increased upon increasing the AsO2- concentration over the range from 10 nM to 10 mu M. The limit of detection at a signal-to-noise ratio of 3 was 2.5 nM, far below the action level of As (133 nM, ca. 10 ppb) permitted by the US EPA for drinking water. Relative to other nanoparticle-based arsenic sensors, this approach is rapid, specific, and sensitive; in addition, it can be applied to the detection of AsO2- in natural water samples (in this case, streamwater, lake water, tap water, groundwater, and mineral water).

• 出版日期2014-3-18