RESUMO
New analytical methods for the determination of free asparagine ï¼Asnï¼, which is a precursor of acrylamide, in grains were developed using LC-MS and LC-MS/MS. Asn was extracted from a sample with 5ï¼ ï¼w/vï¼ aqueous trichloroacetic acid solution, appropriately diluted with 0.1ï¼ ï¼v/vï¼ formic acid solution, and then analyzed by LC-MS or LC-MS/MS. HPLC separation was performed by isocratic elution on a Penta Fluoro Phenyl ï¼PFPï¼ column using 0.1ï¼ ï¼v/vï¼ formic acid and acetonitrile mixture as the mobile phase. The calibration curve was linear in the range of 0.005-0.1 µg/mL. The mean recoveries from potato starch, non-glutinous rice flour and whole wheat flour ranged from 95.4 to 100.9ï¼ , repeatability ï¼RSDï¼ ranged from 0.9 to 6.0ï¼ , and within-laboratory reproducibility ï¼RSDwrï¼ ranged from 2.8 to 7.1ï¼ . Limits of quantitation ï¼LOQsï¼ were 7 mg/kg for potato starch, and 5 mg/kg for non-glutinous rice flour. In addition, an inter-laboratory study was performed in 10 laboratories using 5 kinds of grains ï¼non-glutinous brown rice flour, corn flour, strong flour, whole wheat flour, and whole rye flourï¼, which naturally contained free asparagine. The HORRATR values ranged from 0.4 to 1.0. These results are within the range of the procedural manual of the Codex Alimentarius Commission, confirming the effectiveness of the developed procedures.