No abstract

New analytical methods for the determination of free asparagine Asn , which is a precursor of acrylamide, in grains were developed using LC-MS and LC-MS/MS. Asn was extracted from a sample with 5 w/v aqueous trichloroacetic acid solution, appropriately diluted with 0.1 v/v 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 PFP column using 0.1 v/v formic acid and acetonitrile mixture as the mobile phase. The calibration curve was linear in the range of 0.005-0.1 μ g/mL. The mean recoveries from potato starch, non-glutinous rice flour and whole wheat flour ranged from 95.4 to 100.9 , repeatability RSD ranged from 0.9 to 6.0 , and within-laboratory reproducibility RSDwr ranged from 2.8 to 7.1 . Limits of quantitation LOQs 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 non-glutinous brown rice flour, corn flour, strong flour, whole wheat flour, and whole rye flour , which naturally contained free asparagine. The HORRAT R 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.

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 solidphase 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 μ g/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.

In order to validate an HPLC-UV method for the determination of free asparagine, which is a precursor of acrylamide, in grains using dansyl derivatization, an inter-laboratory study was performed in 9 laboratories using 5 kinds of grains (non-glutinous brown rice flour, corn flour, strong flour, whole wheat flour, and whole rye flour), which naturally contain free asparagine. The relative standard deviations for repeatability (RSDr) and reproducibility (RSDr) were in the ranges of 0.5-2.2 and 2.3-5.9%, respectively. The HorRat values ranged from 0.4 to 0.6. These results were within the range of the procedural manual of the Codex Alimentarius Commission, and therefore the method is effective.