AbstractA fluorometric method was developed for simultaneous determination of Cr(VI) and Cr(III) ions using graphitic carbon nitride nanosheets (g-C3N4 NS) as a nanosized fluorescent indicator probe. The g-C3N4 NS were prepared using high-temperature carbonization of melamine followed by ultrasonication-assisted liquid exfoliation. The g-C3N4 NS display fluorescence with excitation/emission peaks located at 320 and 450 nm. The chromium speciation is based on the quenching of g-C3N4 NS fluorescence. The total concentration of chromium is determined after oxidation of Cr(III) to Cr(VI). The Cr(III) content was then calculated by subtracting the concentration of Cr(VI) from that of total chromium. The effects of pH value, probe amount, and contact time are optimized. Under optimum conditions, calibration plots are linear in the range in the 0.01 to 100 μM chromium concentration range. The limit of detection is 3 nM for for Cr(VI). The intra- and inter-day relative standard deviations (RSD) of the assay are 3.6–7.5% and 4.1–8.5%, respectively. The indicator probe was applied to the determination of chromium species in spiked water and food samples, and recoveries were satisfactory (93.9–107.0%). Graphical abstractGraphitic carbon nitride nanosheets are synthesized by melamine carbonization and employed for Cr speciation in water and food real samples. Total Cr(VI) and Cr(VI) are assessed based on the quenching of the fluorescence of nanosheets by Cr(VI).

中文翻译：

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石墨氮化碳纳米片作为铬物种形成的荧光探针

摘要 使用石墨氮化碳纳米片 (g-C3N4 NS) 作为纳米尺寸的荧光指示探针，开发了一种用于同时测定 Cr(VI) 和 Cr(III) 离子的荧光法。g-C3N4 NS 是使用三聚氰胺的高温碳化然后超声辅助液体剥离制备的。g-C3N4 NS 显示荧光，激发/发射峰位于 320 和 450 nm。铬形态基于 g-C3N4 NS 荧光的猝灭。铬的总浓度是在 Cr(III) 氧化成 Cr(VI) 之后确定的。然后通过从总铬的浓度中减去 Cr(VI) 的浓度来计算 Cr(III) 的含量。优化了pH值、探针量和接触时间的影响。在最佳条件下，校准图在 0 范围内呈线性。01 至 100 μM 铬浓度范围。Cr(VI) 的检测限为 3 nM。该测定的日内和日间相对标准偏差 (RSD) 分别为 3.6-7.5% 和 4.1-8.5%。该指示探针用于测定加标水和食品样品中的铬种类，回收率令人满意（93.9-107.0%）。图形摘要石墨氮化碳纳米片是通过三聚氰胺碳化合成的，并用于水和食品实际样品中的 Cr 形态。总 Cr(VI) 和 Cr(VI) 的评估基于 Cr(VI) 对纳米片荧光的淬灭。该指示探针用于测定加标水和食品样品中的铬种类，回收率令人满意（93.9-107.0%）。图形摘要石墨氮化碳纳米片是通过三聚氰胺碳化合成的，并用于水和食品实际样品中的 Cr 形态。总 Cr(VI) 和 Cr(VI) 的评估基于 Cr(VI) 对纳米片荧光的淬灭。该指示探针用于测定加标水和食品样品中的铬种类，回收率令人满意（93.9-107.0%）。图形摘要石墨氮化碳纳米片是通过三聚氰胺碳化合成的，并用于水和食品实际样品中的 Cr 形态。总 Cr(VI) 和 Cr(VI) 的评估基于 Cr(VI) 对纳米片荧光的淬灭。