Abstract The microwave-assisted digestion of dietary supplements using diluted nitric acid under oxygen pressure for subsequent indirect determination of phosphorus and sulfur by ion chromatography (IC) was proposed. Different concentrations of nitric acid (from 1 to 14.4 mol L−1) and oxygen pressures (from 5 to 20 bar) were evaluated. Dissolved organic carbon and residual acidity were used to choose the most suitable digestion condition. Using the proposed method, it was possible to digest up to 1350 mg of dietary supplements using only 5 mol L−1 HNO3 under 5 bar of oxygen pressure. Comparing to conventional digestion procedure it was possible to digest up to 60% higher sample mass using HNO3 around 30% more diluted. Recoveries ranging from 96 to 102% were obtained when recovery tests using a standard solution or a mixture with certificate reference material were carried out. The concentration of P and S indirectly determined by IC agreed with the results obtained by conventional microwave-assisted digestion using concentrated HNO3 and subsequent determination by inductively coupled plasma optical emission spectrometry.

中文翻译：

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离子色谱法测定膳食补充剂中总磷和硫的新方法和可行方法

摘要 提出了在氧气压力下使用稀硝酸微波辅助消化膳食补充剂，随后通过离子色谱 (IC) 间接测定磷和硫。评估了不同浓度的硝酸（从 1 到 14.4 mol L-1）和氧气压力（从 5 到 20 bar）。溶解有机碳和残余酸度被用来选择最合适的消化条件。使用所提出的方法，在 5 巴的氧气压力下，仅使用 5 mol L-1 HNO3 就可以消化多达 1350 毫克的膳食补充剂。与传统消解程序相比，使用稀释约 30% 的 HNO3 可以消解多达 60% 的样品质量。使用标准溶液或与证书参考物质的混合物进行回收率测试时，回收率在 96% 到 102% 之间。由 IC 间接测定的 P 和 S 浓度与使用浓 HNO3 的常规微波辅助消解和随后通过电感耦合等离子体发射光谱法测定的结果一致。