Nitrogen and sulfur-doped Carbon Quantum Dots as fluorescent probe for inorganic arsenic sensing in water and seaweed
Francisco Eduardo Holanda Lima1, Carlos Mateus Paiva Oliveira2, André Assunção Ferreira2
1Advanced Materials Chemistry Group (GQMat), Department of Analytical Chemistry and Physical Chemistry, Federal University of Ceara - UFC, Campus do Pici, CP 12100, CEP, 60451-970 Fortaleza, CE, Brazil; Applied Chemistry Study Laboratory (LEQA), Department of Analytical Chemistry and Physical Chemistry, Federal University of Ceara - UFC, Campus do Pici, CP 12100, CEP, 60451-970 Fortaleza, CE, Brazil.
Abstract:
The inorganic arsenic species (iAs), As (III) and As (V), are the most toxic arsenic (As) chemical forms, being considered carcinogenic. The main sources of As exposure for humans are water and food. Thus, it is crucial monitoring iAs in these matrices. In general, these As species are analyzed by high-performance liquid chromatography hyphenated with inductively coupled plasma mass spectrometry (HPLC-ICP-MS). In this work, a non-chromatographic alternative method based on Carbon Quantum Dots (CQDs) using fluorescence as detector for iAs analysis was developed. Nitrogen- and sulfur-doped carbon quantum dots (N,S-CQDs) with a high quantum yield (QY) of 32.22% ± 1.27 were employed as turn-off sensors. This work describes the optimization of the synthesis of N,S-CQDs derived from citric acid, ethylenediamine, and mercaptosuccinic acid via the hydrothermal method. The N,S-CQDs were characterized and applied to iAs sensing in well water and seaweed samples, showing detection limits (LOD) below 0.92 μg L-1. The accuracy of iAs quantification in seaweed sample was verified comparing the result with inductively coupled plasma optical emission spectrometry (ICP-OES) analysis after magnetic solid phase extraction using Fe3O4@DTPMP nanoparticles (101% recovery), while for well water samples addition and recovery test was applied (95% to 104% recovery). The iAs mass fraction value found in seaweed sample was 2.55 ± 0.02 mg L-1, and the values in well water samples were below LOD. The proposed method reveled greater environmental friendliness compared to the traditional techniques according to greenness assessment.
