Analysis of 2-Alkylcyclobutanones with Accelerated Solvent Extraction To Detect Irradiated Meat and Fish

Abstract

A new analytical procedure has been developed to analyze 2-alkylcyclobutanones to detect gamma-ray-irradiated fat-containing foodstuffs. Samples were extracted with an accelerated solvent extraction system via hot and pressurized ethyl acetate in cells. A large amount of fat in the extract was precipitated and removed with filtration by standing at -20 degrees C after the addition of acetonitrile. The extract was further cleaned with a 1 g silica gel mini column, and the radiolytic compounds of 2-docecylcyclobutanone (2-DCB) and 2-tetradecylcyclobutanone (2-TCB) were determined with gas chromatography with mass spectrometry (GC/MS). Sample preparation time before GC/MS was 7-8 h. At first, the procedure was evaluated with a recovery test in eight samples spiked with 2-DCB and 2-TCB at 20 ng/g, resulting in 70-105% recoveries with mostly less than 10% relative standard deviations. The procedure was further evaluated with beef, pork, chicken, and salmon samples irradiated with gamma-rays from 0.7 to 7.0 kGy at -19 degrees C. Both 2-DCB and 2-TCB in most samples were detected with good dose-response relations at all doses, while salmon was detected more than 2 kGy irradiation. The amounts of 2-alkylcyclobutanones produced reflected precursor fatty acids levels in samples, especially for the combination of 2-TCB and stearic acid. The results indicated that the production rate of 2-TCB to stearic acid was more obvious than that of 2-DCB to palmitic acid in frozen samples with gamma-ray irradiation.

Detection of Irradiated Food Using 2-Alkylcyclobutanones as Markers: Verification of the European Committee Standardization Method EN1785 for the Detection of Irradiated Food Containing Lipids

“…The ratios of DCB to TCB in chicken and salmon were relatively close to those of palmitic acid to stearic acid, while the ratios of DCB to TCB in beef and pork were significantly lower than those of palmitic acid to stearic acid. Obana et al have reported a similar relationship of DCB and TCB and their precursor fatty acids in irradiated animal meat and salmon 14) ῌ The amounts of DCB and TCB formed on irradiation are sensitive to the temperature during irradiation. The DCB/TCB ratios in frozen beef and pork were about 60῍ lower than those in fresh pork and beef 20), 21) ῌ All the samples in our study were irradiated in the frozen state.…”

Rapid Analysis of 2-Alkylcyclobutanones in Irradiated Meats, Cheese and Salmon by Direct Solvent Extraction Followed by GPC

“…This method is time-consuming and includes two preparation steps: lipids are extracted with n-hexane for 6 h using a Soxhlet apparatus, followed by cleanup using large-scale Florisil column chromatography. Two methods with shorter sample preparation times and improved extraction efficiency for 2-ACBs have been developed, but both require costly equipment: supercritical fluid extraction (SFE) 8),9) and accelerated solvent extraction (ASE) 10) .…”

“…The EN1785 method uses the following cleanup procedure: 0.2 g of extracted lipid (in 5 mL n-hexane) is passed through a bed of 20 deactivated Florisil (36 g) in a column, which is washed with 150 mL n-hexane and eluted with 150 mL of diethyl ether-n-hexane (1 : 99). Obana et al 10) developed a defatting procedure in which lipid is extracted by ASE using ethyl acetate, precipitated via filtration after standing at 20 following the addition of acetonitrile, and cleaned up by passing the sample through a 1 g silica gel cartridge.…”

“…Extracted sample solution was purified on a GPC sys- Sample cleanup using SPE Sample cleanup was carried out according to Obana et al 10) Briefly, the fraction collected from GPC was applied to a 1 g silica gel cartridge, 10 mL n-hexane was passed through the cartridge and discarded, and the 2-ACBs fraction was eluted in 10 mL of 2 diethyl ether in nhexane. The 2-ACBs fraction was evaporated almost to dryness, and the residue was dissolved in 0.5 mL n-hexane containing 0.05 μg/mL 2-HCH (internal standard) and 0.1 μg/mL polyethylene glycol 200 (PEG 200).…”

“…Obana et al 10) reported that silica gel cartridges could be used for the purification step instead of large-scale Florisil columns because most of the lipid is removed by their defatting procedure with ASE prior to cartridge purification. We first attempted to use small-scale silica gel cartridges with samples of 2-ACBs in large volumes of cyclohexane.…”