SPECIATION ANALYSIS OF ARSENIC IN RICE USING HIGH PERFORMANCE LIQUID CHROMATOGRAPHY COUPLED WITH HYDRIDE GENERATION ATOMIC FLUORESCENCE SPECTROMETRY (HPLC-HG-AFS)

The aim of this work was to develop a method using high performance liquid chromatography coupled with hydride generation atomic fluorescence spectrometry (HPLC-HG-AFS) for the determination and speciation analysis of the inorganic and organic species of arsenic found most often in rice samples: As(V), As(III), monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA). The best chromatographic resolution was obtained using pH 6.2, a phosphate buffer mobile phase concentration of 20 mmol L-1 and flow rate of 0.57 mL min-1, HCl concentration of 5.55% (v/v), and NaBH4 concentration of 0.90% (w/v). The accuracy of the method was confirmed by the low relative error values obtained for analysis of a certified reference material (NIST 1568b): 6.63% (total inorganic As), 3.44% (DMA), 0% (MMA), and 0.53% (total As). In recovery tests, the proposed method achieved satisfactory recoveries in the range 86-110%.

本研究旨在开发一种结合高效液相色谱-氢化物发生原子荧光光谱法（HPLC-HG-AFS）的分析方法，用于测定大米样品中最常见的砷的无机与有机形态并开展形态分析，涉及的砷形态包括五价砷（As(V)）、三价砷（As(III)）、一甲基胂酸（monomethylarsonic acid, MMA）以及二甲基次胂酸（dimethylarsinic acid, DMA）。实验优化得到的最佳色谱分离条件为：采用pH 6.2的磷酸盐缓冲液作为流动相，其浓度为20 mmol·L⁻¹，流速0.57 mL·min⁻¹；同时使用5.55%（v/v）的盐酸溶液与0.90%（w/v）的硼氢化钠溶液作为衍生试剂体系。通过对标准参考物质（NIST 1568b）进行分析得到的相对误差值验证了本方法的准确性：总无机砷为6.63%，DMA为3.44%，MMA为0%，总砷为0.53%。在回收率实验中，本方法的回收率处于86%~110%区间，结果令人满意。