[Development of an HPLC-UV Method for Free Asparagine in Grains]

A novel analytical method was developed for the determination of free asparagine (Asn), which is a precursor of acrylamide, in grains. Asn was extracted from a sample with 5% (w/v) aqueous trichloroacetic acid solution, and the crude extract was cleaned up using a reversed-phase solid-phase cartridge. The cleaned extract was derivatized with dansyl chloride and analyzed by HPLC-UV. HPLC separation was performed by gradient elution on a ODS column using 0.01 mol/L ammonium acetate and acetonitrile mixture as the mobile phase. The calibration curve was linear in the range of 0.5-100 μg/mL. The mean recoveries from potato starch, non-glutinous rice flour and whole wheat flour ranged from 97.7 to 102.6%, the repeatability (RSDs) ranged from 0.8 to 2.0%, and the within-laboratory reproducibility (RSDwr) ranged from 1.4 to 6.2%. Limits of quantitation (LOQs) were 13 mg/kg for potato starch and 4 mg/kg for non-glutinous rice flour. The quantitative values obtained for about 15 kinds of grains using this developed method were approximately equal to those obtained with an automatic amino acid analyzer.