Laboratory of Toxicant and Drug Analyses, Faculty of Pharmaceutical Sciences, Federal University of Alfenas, 37130-001, Alfenas, MG, Brazil; Institute of Chemistry, Federal University of Alfenas, 37130-001, Alfenas, MG, Brazil.
Institute of Chemistry, Federal University of Alfenas, 37130-001, Alfenas, MG, Brazil.
Anal Chim Acta. 2023 Apr 22;1251:340709. doi: 10.1016/j.aca.2022.340709. Epub 2022 Dec 10.
A procedure of direct magnetic sorbent sampling in flame atomic absorption spectrometry (DMSS-FAAS) was developed in this work. Metal-loaded magnetic sorbents were directly inserted in the flame of the FAAS for direct metal desorption/atomization. Magnetic graphene oxide aerogel (M-GOA) particles were synthesized, characterized, and used as a proof-of-concept in the magnetic dispersive solid phase extraction of Pb ions from water samples. M-GOA was selected because is a light and porous sorbent, with high adsorption capacity, that is quickly burned by the flame. Magnetic particles were directly inserted in the flame by using a metallic magnetic probe, thereby avoiding the need for a chemical elution step. As all the extracted Pb ions arrive to the flame without passing through the nebulization system, a drastic increase in the analytical signal was achieved. The improvement in the sensitivity of the proposed method (DMSS-FAAS) for Pb determination was at least 40 times higher than the conventional procedure in which the Pb is extracted, eluted, and analyzed by conventional flame atomic absorption spectrometry (FAAS) via the nebulization system. The analytical curve was linear from 5.0 to 180.0 μg L and the limit of detection was found to be 1.30 μg L. Background measurements were insignificant, and the atomic absorption peaks were narrow and reproducible. Precision assessed as a percentage of the relative standard deviation %RSD was found to be 17.4, 7.1, and 7.8% for 10, 70, and 180 μg L levels, respectively. The method showed satisfactory results even in the presence of other ions (Al, Cr, Co, Cu, Fe, Mn, Ba, Mg, and Li). The performance of the new system was also evaluated for Cd ions, as well as by using other magnetic particles available in our lab: magnetic carbon nanotubes (M-CNTs), magnetic restricted access carbon nanotubes (M-RACNT), magnetic poly (methacrylic acid-co-ethylene glycol dimethacrylate) (M-PMA), magnetic nanoparticles coated with orange powder peel (M-OPP), and magnetic nanoparticles covered with SiO (M - SiO). Analytical signals increased for both analytes in all sorbents (increases of about 4-37 times), attesting the high potential and applicability of the proposed method. Simplicity, high analytical frequency, high detectability and reproducibility, low cost, and possibility of being totally mechanized are the most relevant advantages.
本文开发了一种火焰原子吸收光谱法中的直接磁固相采样（DMSS-FAAS）程序。将负载金属的磁性固相萃取剂直接插入 FAAS 火焰中，实现金属的直接解吸/原子化。本文制备了磁性氧化石墨烯气凝胶（M-GOA）颗粒，并将其用作水样中 Pb 离子磁性分散固相萃取的概念验证。选择 M-GOA 是因为它是一种轻量多孔的吸附剂，具有高吸附容量，且可以迅速被火焰燃烧。通过使用金属磁性探头将磁性颗粒直接插入火焰中，从而避免了化学洗脱步骤。由于所有提取的 Pb 离子都无需通过雾化系统到达火焰，因此分析信号得到了极大的增强。与传统的通过雾化系统进行 Pb 提取、洗脱和分析的常规火焰原子吸收光谱法（FAAS）相比，该方法对 Pb 测定的灵敏度提高了至少 40 倍。分析曲线的线性范围为 5.0 至 180.0 μg L，检出限为 1.30 μg L。背景测量无显著影响，原子吸收峰窄且重现性好。以相对标准偏差（%RSD）的百分比评估的精密度，在 10、70 和 180 μg L 水平下分别为 17.4%、7.1%和 7.8%。即使存在其他离子（Al、Cr、Co、Cu、Fe、Mn、Ba、Mg 和 Li），该方法也能得到令人满意的结果。还评估了新系统对 Cd 离子的性能，以及使用我们实验室中其他可用的磁性颗粒：磁性碳纳米管（M-CNTs）、磁性受限通道碳纳米管（M-RACNT）、磁性聚（甲基丙烯酸-co-乙二醇二甲基丙烯酸酯）（M-PMA）、用橙皮粉包被的磁性纳米粒子（M-OPP）和用 SiO 包被的磁性纳米粒子（M-SiO）。所有吸附剂中两种分析物的分析信号均增加（增加约 4-37 倍），证明了该方法具有很高的潜力和适用性。该方法的最大优点是简单、高分析频率、高检测性和重现性、低成本以及完全机械化的可能性。
