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%.