title: Analysis of gamma-irradiated melon, pumpkin, and sunflower seeds by electron paramagnetic resonance spectroscopy and gas chromatography-mass spectrometry.
abstract: Seeds of melon (Citrullus lanatus var. sp.), pumpkin (Cucurbita moschata), and sunflower (Heliantus annus) were gamma-irradiated at 1, 3, 5, and 10 kGy and analyzed by electron paramagnetic resonance (EPR) and gas chromatography-mass spectrometry (GC-MS) according to EN1787:2000 and EN1785:2003, respectively. Distinguishable triplet signals due to the presence of induced cellulose radicals were found at 2.0010-2.0047 g in the EPR spectra. The gamma-irradiated radiolytic markers of 2-dodecylcyclobutanone (2-DCB) and 2-tetradecylcyclobutanone (2-TCB) were identified in all irradiated seed samples. Both the free radicals and the alkylcyclobutanones were found to increase with irradiation dose. In general, linear relationships between the amount of radicals and irradiation dosage could be established. Studies at an ambient temperature (20-25 degrees C) in a humidity-controlled environment showed a complete disappearance of the cellulosic peaks for irradiated samples upon 60 days of storage. Such instability behavior was considered to render the usefulness of using EPR alone in the determination of irradiated seed samples. On the other hand, 2-DCB and 2-TCB were also found to decompose rapidly (>85% loss after 120 days of storage), but the radiolytic markers remained quantifiable after 120 days of postirradiation storage. These results suggest that GC-MS is a versatile and complimentary technique for the confirmation of irradiation treatment to seeds.
authors.affiliation: Analytical and Advisory Services Division, Government Laboratory of the Hong Kong Special Administrative Region, Homantin Government Offices, Homantin, Hong Kong. wmsin@govtlab.gov.hk
authors.forename: Della W M
authors.initials: DW
authors.lastname: Sin
authors.forename: Yiu Chung
authors.initials: YC
authors.lastname: Wong
authors.forename: Wai Yin
authors.initials: WY
authors.lastname: Yao
mesh_terms: D028464:Cucurbita / Q000737:chemistry / Q000528:radiation effects*; D019662:Cucurbitaceae / Q000737:chemistry / Q000528:radiation effects*; D004578:Electron Spin Resonance Spectroscopy; D005514:Food Irradiation; D005720:Gamma Rays; D008401:Gas Chromatography-Mass Spectrometry; D006368:Helianthus / Q000528:radiation effects*; D012639:Seeds / Q000737:chemistry / Q000528:radiation effects*