Hexavalent chromium is much more toxic than trivalent chromium and is severe environmental pollution caused by human activity. The presence of Cr(VI) ions in waters comes from anthropogenic sources, mainly from industries, and poses an enormous danger. Because of the health effects of Cr(VI) ions on humans, even at very low concentrations, it is necessary to control its levels in the water. However, the determination and speciation of Cr(VI) in water samples remains a sophisticated subject, and according to the WHO recommendation, further studies on reliable and validated methods should be continued. In this study, graphene oxide (GO) was modified with tetraethylenepentamine (TEPA) for the highly effective adsorption and determination of Cr(VI) ions by energy-dispersive X-ray fluorescence (EDXRF) and total-reflection X-ray fluorescence spectrometry (TXRF). The experiment shows that Cr(VI) ions can be adsorbed from aqueous solutions at pH 3.5 with a maximum adsorption capacity of 102 mg g using minimal adsorbent doses, 10–50 μg mL, much lower than those of the currently reported adsorbents. These adsorptive properties of GO-TEPA and selectivity toward Cr(VI) in the presence of Cr(III) indicate its potential use as a micro-adsorbent in the determination and speciation of chromium. Due to the high preconcentration factors of 865 and 100, for EDXRF and TXRF, respectively, and high recovery of 98.5–100%, the method based on dispersive micro-solid phase extraction allows obtaining extremely low detection limits of 53 and 3.5 pg mL for EDXRF and TXRF. The exceptional adsorptive properties of GO-TEPA, including the possibility of application in micro-quantities, allow for the development of the ultra-trace method according to the fundamental principles of green analytical chemistry. It significantly expands the possibilities of using the EDXRF, as well as the TXRF technique in water analysis.

中文翻译：

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使用分散微固相萃取和四亚乙基五胺氧化石墨烯，通过 EDXRF 和 TXRF 测定六价铬的超痕量和形态

六价铬的毒性比三价铬大得多，是人类活动造成的严重环境污染。水中存在的六价铬离子来自人为来源，主要来自工业，构成了巨大的危险。由于 Cr(VI) 离子对人体的健康影响，即使浓度非常低，也有必要控制其在水中的含量。然而，水样中六价铬的测定和形态仍然是一个复杂的课题，根据世界卫生组织的建议，应继续对可靠和经过验证的方法进行进一步研究。在这项研究中，氧化石墨烯（GO）被四乙烯五胺（TEPA）修饰，通过能量色散X射线荧光（EDXRF）和全反射X射线荧光光谱法高效吸附和测定Cr（VI）离子。发射光谱）。实验表明，使用最小吸附剂剂量（10-50 μg/mL）即可从 pH 3.5 的水溶液中吸附 Cr(VI) 离子，最大吸附容量为 102 mg g-1，远低于目前报道的吸附剂。GO-TEPA 的这些吸附特性以及在 Cr(III) 存在下对 Cr(VI) 的选择性表明其在铬的测定和形态形成中作为微吸附剂的潜在用途。由于 EDXRF 和 TXRF 的预富集因子分别为 865 和 100，以及 98.5-100% 的高回收率，基于分散微固相萃取的方法可以获得 53 和 3.5 pg mL 的极低检测限。 EDXRF 和 TXRF。GO-TEPA 卓越的吸附特性（包括微量应用的可能性）允许根据绿色分析化学的基本原理开发超痕量方法。它显着扩展了在水分析中使用 EDXRF 以及 TXRF 技术的可能性。