HPLC Determination of Acrylamide in Fried Food with SPE Using Nano-MnO₂ as Adsorbent

Nano-manganese dioxide (nMnO₂) was prepared and the product obtained was characterized by FTIR and SEM. nMnO₂ was used as adsorbent in SPE for separation and enrichment of acrylamide (AA) in fried food and determined by HPLC. A portion (2.000 0 g) of the powdered sample was taken and extracted by vibration thrice with methanol (8 mL, 6 mL and 6 mL) for 20 min in each extraction. After phase-separation by centrifugation, the 3 supernatants were collected, combined and evaporated at 40 ℃ to ca. 6 mL by N₂-blowing. The concentrate was refrigerated at 4 ℃ for 2 h, and then centrifuged. The sepernatant was taken and extracted 4 times with n-hexane (6 mL were added in each extraction). The 4 supernatants were collected, combined and concentrated at 40 ℃ to ca. 1.6 mL by N₂-blowing. The sample solution was then passed through the SPE micro column which was packed with 200 mg of nMnO₂. Flow-rate taken for the sample solution was 2.0 mL·min^-1. The micro column was rinsed with 0.5 mL of a mixture of CH₃OH and water (40+60) flowing at a rate of 6.0 mL·min^-1 to eliminate impurites. The 0.8 mL of a mixture of acetonitrile and glacial acetic acid (99+1) was passed through the micro column at a flow rate of 1.0 mL·min^-1, to elute adsorted AA from the column. The eluate obtained was filtered through 0.25 μm filtering membrane, and an aliquot of 10 μl was introduced into the instrument for HPLC analysis. Enrichment factor obtained by this method was attained to a value of 148. Linear relationship was obtained between values of peak areas and mass concentration of AA in the range of 0.5 to 250 μg·L^-1, with detection limit (3S/N) of 0.054 μg·L^-1. Samples of 5 different fried food were analyzed by the proposed method, and test for recovery was made by addition of AA standard solution to the 5 samples as matrixes, giving results of recovery in the range of 80.0% to 96.0%. Values of RSDs (n=5) found were in the range of 2.4% to 8.8%.