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%.

本研究旨在建立一种采用高效液相色谱-氢化物发生原子荧光光谱联用技术（high performance liquid chromatography coupled with hydride generation atomic fluorescence spectrometry, HPLC-HG-AFS）的分析方法，用于大米样品中最常见的砷的无机与有机形态的测定与形态分析：五价砷(As(V))、三价砷(As(III))、一甲基胂酸(MMA)以及二甲基次胂酸(DMA)。当采用pH 6.2的磷酸盐缓冲液作为流动相（浓度20 mmol·L⁻¹，流速0.57 mL·min⁻¹）、5.55%（体积分数）盐酸溶液及0.90%（质量体积分数）硼氢化钠溶液时，可获得最佳色谱分离度。本方法的准确性通过对标准参考物质（NIST 1568b）的分析得到的极低相对误差值得以验证：总无机砷为6.63%、二甲基次胂酸为3.44%、一甲基胂酸为0%、总砷为0.53%。加标回收实验中，本方法的回收率处于86%~110%区间，结果令人满意。