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Analysis of 2-Acetyl-1-Pyrroline in Rice by HSSE/GC/MS

¹USDA-ARS-Southern Regional Research Center, 1100 Robert E. Lee Blvd., New Orleans, LA 70124. ²Corresponding author. Phone: (504) 286-4293. Fax: (504) 286-4419. E-mail: casey.grimm@ars.usda.gov ³USDA-ARS-Dale Bumpers National Rice Research Center, 2890 Highway 130 E, Stuttgart, AR 72160.

An extremely sensitive method for the analysis of 2-acetyl-1-pyrroline (2AP) in rice, employing stir bar sorptive extraction (Twister) was studied. The Twister stir bar is placed in the headspace of a 20-mL vial containing 1 g of rice kernels, 7.5 mL of 0.1M KOH, and 2.2 g of NaCl, along with a second Teflon-coated stir bar for mixing. Analytes are adsorbed onto the Twister for 4 hr at 40°C and then desorbed at 270°C into a GC column while cryofocusing at –80°C. The headspace sorptive extraction (HSSE) method was able to detect <0.1 ppb of 2AP in rice. The precision of the HSSE method (>10%) was not as good as the GC/FID method (≈6%). Using HSSE, 2AP was observed in all samples generally considered to be aromatic and was not observed in any nonaromatic samples. Additionally, a modified method for the synthesis of 2-acetyl-1-pyrroline was studied and the presence of a tautomer of 2-acetyl-1-pyrroline was confirmed.